- Email: [email protected]
Multimodality Treatment of Posterior Inferior Cerebellar Artery Aneurysms
Accepted Manuscript Multimodality Treatment of Posterior Inferior Cerebellar Artery Aneurysms Justin R. Mascitelli, MD, Kurt Yaeger, MD, Daniel Wei, BS, Christopher P. Kellner, MD, Thomas J. Oxley, MD, PhD, Reade A. De Leacy, MD, Johanna T. Fifi, MD, Aman B. Patel, MD, Thomas P. Naidich, MD, Joshua B. Bederson, MD, J. Mocco, MD, MS PII:
S1878-8750(17)31124-5
DOI:
10.1016/j.wneu.2017.07.024
Reference:
WNEU 6086
To appear in:
World Neurosurgery
Received Date: 13 May 2017 Revised Date:
3 July 2017
Accepted Date: 6 July 2017
Please cite this article as: Mascitelli JR, Yaeger K, Wei D, Kellner CP, Oxley TJ, De Leacy RA, Fifi JT, Patel AB, Naidich TP, Bederson JB, Mocco J, Multimodality Treatment of Posterior Inferior Cerebellar Artery Aneurysms, World Neurosurgery (2017), doi: 10.1016/j.wneu.2017.07.024. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Multimodality Treatment of PICA Aneurysms 1
Title: Multimodality Treatment of Posterior Inferior Cerebellar Artery Aneurysms
2 Authors: Justin R. Mascitelli, MD1; Kurt Yaeger, MD1; Daniel Wei, BS1; Christopher P.
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Kellner, MD1; Thomas J. Oxley, MD, PhD1,; Reade A. De Leacy, MD1; Johanna T. Fifi, MD1;
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Aman B. Patel, MD2; Thomas P. Naidich, MD3; Joshua B. Bederson, MD1; J Mocco, MD, MS1
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Department of Neurosurgery, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical School,
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Boston, MA, USA 3
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Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
11 Correspondence To:
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Justin Mascitelli, MD
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Mount Sinai Health System
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Department of Neurosurgery
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1450 Madison Avenue
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Klingenstein Clinical Center, 1-North
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New York, New York, USA 10029
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Tel: 212-241-3400
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Fax: 646-537-2299
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Email: [email protected]
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Key Words: aneurysm, clipping, coiling, PICA
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Running Title: Multimodality Treatment of PICA Aneurysms
25 Disclosure: The authors report no conflict of interest concerning the materials or methods used
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in this study or the findings specified in this paper. None of the conflicts of interest listed below
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had any influence on this work but are being listed for completeness.
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Thomas Oxley is the founder and shareholder of Synchron.
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Reade De Leacy is a consultant to DFine and Medical Metrics.
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Johanna Fifi is a consultant to Microvention and Penumbra and holds a grant from
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Stryker.
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Aman Patel is a consultant to Penumbra and Medtronic/Covidien
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Dr. Mocco receives research funding support for ongoing clinical trials from Stryker Neurovascular, Penumbra, Medtronic Neurovascular, and Microvention. He is an
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investor in Blockade Medical, TSP and Cerebrotech. He is a consultant for TSP,
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Cerebrotech, Rebound, Pulsar, and Endostream.
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Previous presentations: None
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ACCEPTED MANUSCRIPT Multimodality Treatment of PICA Aneurysms Abstract
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OBJECT Posterior inferior cerebellar artery (PICA) aneurysms are heterogeneous, uncommon
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lesions that can be treated in many fashions. Many previous series have focused on a specific
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aneurysm subset or treatment paradigm. The aim of this study was to present a comprehensive
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approach for all PICA aneurysms and analyze outcomes by PICA location.
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METHODS All PICA aneurysms treated from 2012 until present were reviewed retrospectively
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and classified by location. Angiographic and clinical outcome were assessed.
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RESULTS We identified 30 patients (average age 56 years, female 76.7%, subarachnoid
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hemorrhage 83.3%) with 30 aneurysms (saccular 50.0%) who underwent 36 treatments.
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Locations included: VA-PICA junction: 8; anterior medullary (AM): 7; lateral medullary: 3;
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tonsillomedullary: 1; telovelotonsillar: 5; and cortical: 6. Treatments included clipping: 6;
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trapping: 2; coiling: 13; balloon-assisted coiling: 1; stent-assisted coiling: 1; flow diversion: 1;
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and endovascular parent vessel occlusion (PVO): 6. There were 3 procedural complications.
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Recurrence and retreatment rates were 23.3% and 20.0%, respectively. Retreatments included
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coiling: 1; clipping: 4; and bypass: 1. Seven patients had an associated cerebellar AVM, of which
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5 have undergone resection. Good clinical outcome was achieved in 43.3% at discharge and
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84.6% at follow-up (average 10.7 months). Aneurysms distal to the AM segment were more
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likely to occur in older patients (P = 0.007), with cerebellar AVMs (P = 0.031), and to be treated
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with PVO (P = .001). Recurrences were more common for AM segment aneurysms (P = 0.016).
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Poor outcome was associated with poor SAH grade (P = 0.010), not aneurysm morphology
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(P=0.356), location (P = 0.867) or treatment type (P = 0.365).
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CONCLUSIONS Our five-year modern experience highlights the diversity of PICA aneurysms
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and the need for multimodality paradigms to treat them successfully. The AM segment has the
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highest recurrence rate. Aggressive management is warranted given that the majority of patients
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can have a good neurological outcome.
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Posterior inferior cerebellar artery (PICA) aneurysms are uncommon lesions that account for approximately 0.5 – 3% of all intracranial aneurysms.1,2 They are highly diverse and their
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sites of origin span from the vertebral artery PICA junction (VPJ) to anywhere along the length
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of the PICA (Figure 1). They may be saccular, dissecting, or fusiform. They may be treated
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utilizing a broad range of microsurgical and endovascular techniques. Although there have been
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a number of published PICA aneurysm series, frequently these series focus on only one
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population of PICA aneurysms (e.g. distal segment) or only one treatment modality (e.g.
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endovascular therapy).3-29 Our modern series highlights the variety of treatment modalities
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available, the efficacy of these treatments for specific aneurysm locations, and the importance of
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treating complex aneurysms at an academic center with specialists in open cerebrovascular,
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endovascular, and neurointensive care.
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Following approval from the Institutional Review Board, retrospective review of
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aneurysms treated over the five-year period from April 2012 to April 2017 disclosed 30 patients
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with 30 PICA aneurysms who underwent 36 interventions. A waiver of consent was obtained to
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perform this retrospective review. Demographic information was obtained from the electronic
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medical record (EMR). Mode of presentation was recorded for all aneurysms and correlated with
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clinical presentation and outcome. Concurrent medical conditions such as trauma, connective
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tissue disease, and drug use were recorded. Hunt Hess score was used for subarachnoid
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hemorrhage (SAH) grade, and poor grade was defined as IV and V. All SAH patients received
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standard Neurosurgical ICU management for at least 2 weeks.
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ACCEPTED MANUSCRIPT Multimodality Treatment of PICA Aneurysms Aneurysms were evaluated on digital subtraction angiography (DSA). By location,
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aneurysms arising at the vertebral artery (VA) – PICA junction (VPJ) and aneurysms arising
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within the 5 segments of PICA (Figure 1): anterior medullary (AM), lateral medullary (LM),
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tonsillomedullary (TM), telovelotonsillar (TVT), and cortical branches (CB) were included in the
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study group. Aneurysms of the VPJ and AM segment were defined as proximal and all others
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distal.14 By type, aneurysms accepted into the study group included saccular and atypical (e.g.
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fusiform and dissecting) aneurysms, and feeding artery aneurysms associated with cerebellar
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AVMs. Intranidal aneurysms were excluded from the study. Aneurysm sizes were measured in
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three dimensions at the time of treatment and recorded in the operative report. The side and
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origin of the affected PICA with respect to the dura were noted in each case.
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For each aneurysm, the treatment type and any procedural complications were
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determined from the operative reports. Treatment for a given aneurysm was based on consensus
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opinion from members of a comprehensive cerebrovascular team, consisting of neurosurgeons,
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neurologists, neuroradiologists, and intensive care specialists. Except in emergency situations,
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cases were typically presented during a daily conference, and treatment was decided after an
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open discussion of risks, benefits, and alternatives of each treatment modality. For patients that
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underwent PVO, postoperative MRI and CT were evaluated for ischemia in the PICA territory.
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The extent of initial aneurysm occlusion was graded utilizing the 3 step Raymond scale:30 Grade
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1 (complete aneurysm occlusion), Grade 2 (residual aneurysm neck), Grade 3 (residual aneurysm
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dome). Follow-up information included any evidence of aneurysm recurrence, any need for re-
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treatment and the type of retreatment selected. Clinical outcome was retrospectively derived
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from the EMR based on the Modified Rankin Scale (mRS). Poor outcome was defined as mRS 3
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– 6.
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Data for PICA aneurysms were assessed by location, angiographic outcome, and clinical outcome. Comparisons were made between the following patient groups: 1) proximal vs. distal
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PICA aneurysm, 2) non-recurrent vs. recurrent, 3) good vs. poor clinical outcome. Continuous
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variables are presented as mean±SD and were compared between groups using Student t tests.
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Categorical variables were compared between groups using χ2 tests. The Mann-Whitney test was
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used to compare age between groups. All reported P values are two-sided with α = 0.05.
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Statistical analyses were performed using the R language for statistical programming (R
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Foundation for Statistical Computing; Vienna, Austria).
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Results
The final study group included 40 patients with 40 PICA aneurysms who underwent 36 separate treatments (Table 1). Most patients were female (76.7%). The average age at
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presentation was 56 years. Most patients (83.3%) presented with subarachnoid hemorrhage
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(SAH). Other presentations included incidental imaging finding (n = 4), and positive family
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history (n=1). The majority of SAH patients (72%) had an initial good Hunt Hess score (I – III).
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Concurrent cerebellar ICH was present in 24% of cases. No patients had a history of trauma,
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connective tissue disease or drug abuse that would predispose to non-saccular aneurysm
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formation.
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The origins of the PICA aneurysms were widely distributed (Table 2; Figures 2 – 7):
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VPJ: 8, AM: 7, LM: 3; TM: 1; TVT: 5; and CB: 6. There was an equal distribution of saccular
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versus atypical aneurysms: 15 (50%) were saccular in morphology, 14 (46.7%) were fusiform,
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and one (3.3%) was a dissecting aneurysm. Non-saccular morphology was associated with
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presence of a cerebellar ICH (P=0.006). Seven aneurysms (23.3%) were inflow aneurysms
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of left (46.7%) and right (53.3%) sided aneurysms. The average maximum dome diameter was
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4.91 mm. The PICA origin was intradural in 93.3% of cases. Both aneurysms with extradural
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PICA origin happened to be fusiform aneurysms of the AM segment. In comparison to proximal
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aneurysms, those distal to the AM segment were associated with older patients (62.3 vs. 49.6
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years, P = 0.007) who harbored cerebellar AVMs (40.0% vs 6.67%, P =0.031).
Primary treatments (Table 3) included microsurgical clipping: 6; surgical trapping: 2;
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stand-alone coiling: 13; balloon-assisted coiling (BAC): 1; stent-assisted coiling (SAC): 1; flow
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diversion (FD)-assisted coiling: 1; and endovascular parent vessel occlusion (PVO): 6.
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Endovascular PVO was performed with coils alone: 2; N-butyl cyanoacrylate (nBCA; Cordis
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Microvascular, Inc., New Brunswick, NJ): 1; Onyx (Medtronic): 2, or a combination of
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materials: 1. Six of the 8 VPJ aneurysms were managed with non-PVO endovascular techniques.
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Four of the 7 aneurysms of the AM segment were treated with clipping. In comparison to
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proximal aneurysms, those distal to the AM segment were more likely to be treated with any
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type of PVO (53.3% vs 0%, P =0 .001). Non-saccular aneurysms were also more likely to be
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treated with PVO (53.3% vs. 0.0%, P=0.001). Of the patients treated with PVO, 25% had
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radiographic ischemic changes in the PICA territory. In addition to aneurysm treatment, one
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patient required a suboccipital craniectomy following aneurysm embolization due to mass effect
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in the posterior fossa and 5 patients went on the have AVM resection (with two more planned at
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the time of writing this manuscript).
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The initial occlusion classification was as follows: complete occlusion (60.0%), neck
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remnant (30.0%), and residual aneurysm (10.0%). The aneurysm recurrence and retreatment
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rates were 23.3% and 20.0%, respectively. Recurrences were seen after initial treatment by
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ACCEPTED MANUSCRIPT Multimodality Treatment of PICA Aneurysms coiling (4), FD (1) and clipping (2). No recurrences were seen after PVO. Recurrences were
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more likely to occur for AM segment aneurysms versus other locations (57.1% vs 15.8%, P =
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0.016). The 4 AM recurrences occurred after coiling (2) and clipping (2). Both of the
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microsurgical AM recurrences (one early and one delayed) occurred in fusiform AM aneurysms
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in which the most diseased portion of the vessel and rupture site was clipped initially but an
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adjacent portion of the vessel ultimately enlarged. One of these recurrences was retreated with
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repeat clipping and the other was retreated with coiling. In total, retreatments included coiling: 1;
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clipping: 4; and bypass: 1. The bypass was performed for a unique case in which the patient had
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an exacerbated chiari malformation secondary to a coil mass, published previously as a case
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report33. The majority of the retreatments (80%) involved changing the approach from
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endovascular to surgical therapy or visa versa. Including the retreatments, 9 different treatment
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types were employed.
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during endovascular treatment. These were vessel perforation in 1 case and vessel compromise in
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two. These complications did not lead to morbidity or mortality. There were no intraoperative
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complications during microsurgical clipping. Three patients experienced delayed complications
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following microsurgical treatment: one with a postoperative abscess requiring surgical
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evacuation, and two with persistent lower cranial nerve dysfunction at follow-up, one mild and
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one severe. In addition, two patients had delayed complications related to VP shunting. The rate
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of good neurological outcome (mRS 0-2) at discharge was 43.3%. The rate of good neurological
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outcome at last known follow-up (average 11 months) was 86.7%. Two patients in this series
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died from complications of the initial SAH. Poor outcome was associated with poor SAH grade
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(P = 0.008). Clinical outcome was not influenced by aneurysm morphology (P=0.356), location
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(P = .867) or treatment type (P = .365).
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Discussion
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The most important finding of our modern series is that a multidisciplinary team is
necessary to treat this heterogeneous group of aneurysms (Figure 8). In 30 patients/aneurysms
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undergoing 36 treatments, we found 3 different aneurysm types, 6 different aneurysm locations,
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9 different treatment strategies (both surgical and endovascular), and an 80% treatment strategy
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change for recurrent aneurysms. Additionally, 83% of patients experience SAH requiring critical
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care management for a number of weeks. Therefore a cohesive team consisting of
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neurosurgeons, interventionalists, and intensivists is necessary to handle this diverse group of
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lesions.
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secondary to attempts to preserve brainstem perforators. This is a novel finding and this
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subgroup of PICA aneurysms may require closer follow-up. Secondly, PVO is a reasonable
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treatment option for distal PICA aneurysms and rarely results in clinically meaningful ischemia.
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Finally, although ruptured PICA aneurysms are notorious for causing poor clinical outcome,31
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our series demonstrate that the vast majority patients with PICA aneurysms have a good outcome
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at follow-up, frequently improved from discharge, and therefore aggressive management is
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warranted.
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PICA Aneurysm Anatomy
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PICA aneurysms are uncommon and account for 0.5-3% of all intracranial aneurysms.1,2 They are heterogeneous in both location and morphology. Although they can occur anywhere
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from the VA-PICA junction to the distal cortical branches of PICA, they most commonly arise
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from the VA-PICA junction.1,22,32 Less often, they occur in a distal PICA segment, accounting
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for approximately 15-30% of all PICA aneurysms.17 Interestingly, in our series, the breakdown
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between proximal and distal was equally matched. Of distal PICA aneurysms, the TVT segment
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has been reported to be the most common site of origin.3 We found that the cortical segment was
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the most common distal location.
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extracranial PICA aneurysms, usually associated with an extradural origin of PICA or caudal
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displacement of the TM segment.33 PICA aneurysms are more likely to have a fusiform
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morphology than other, non-PICA aneurysms.20,26 Dissecting PICA aneurysms have been found
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more typically to occur in distal PICA segments.19,26 Additionally, atypical aneurysms have been
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associated with worse clinical outcomes.34 In our series, half of the patients had saccular
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aneurysms and half atypical aneurysms. We did not find differences in radiographic our clinical
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outcome base on aneurysm morphology.
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Treatment Options
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Given the diversity of location and morphology amongst PICA aneurysms, no single
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treatment can be consistently employed. Microsurgical treatment options include clipping,
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trapping/PVO, resection, as well as a variety of bypasses procedures. Endovascular treatment
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options include stand-alone coiling, BAC, SAC, FD, or PVO with coils, liquid embolic material
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or both. Occasionally, a combination of both microsurgical and endovascular techniques is
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entirely on aneurysm morphology, location and surgeon/interventionalist comfort. Additionally,
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PICA aneurysms are frequently associated with cerebellar AVMs (23.3% in our series), which
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are ideally managed with surgical resection with or without preoperative embolization.
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Microsurgical Treatment
For proximal PICA aneurysms, the far lateral approach provides access to the cerebello-
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medullary fissure (CMF).1,35 There are many versions of the far lateral approach, but most
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involve a suboccipital craniectomy, C1 laminectomy, and resection of the medial portion of the
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occipital condyle (to varying degrees). When used for PICA aneurysms, this approach is
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associated with favorable outcomes, low postoperative morbidity, and no greater morbidity in
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comparison to craniotomies for posterior communicating aneurysms.36 Recently, Seoane et al
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published a surgical series utilizing the far lateral approach for PICA aneurysms without
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condylar resection.29 Rodriguez-Hernandez and Lawton described the vagoaccessory triangle,
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bordered medially by the medulla, laterally by the spinal accessory nerve (CN XI), and
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superiorly by the vagus nerve (CN X),37 as the anatomic corridor to reach PICA aneurysms. The
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triangle is subdivided into the supra- and infra-hypoglossal triangles by the hypoglossal nerve
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(CN XII). Further, the PICA origin will determine whether a VA-PICA junction aneurysm arises
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in the AM, LM, or TM zone. Identification of the extradural vertebral artery is essential for
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proximal control. Maintaining a caudal to rostral view beneath the cranial nerves rather than
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through them may reduce postoperative cranial nerve dysfunction.38 For aneurysms of more
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distal, cortical PICA segments, a midline suboccipital craniectomy is sufficient.39
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clipping.17,20,37,39 Compared to aneurysms in other location, PICA aneurysms are more likely to
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have a fusiform or non-saccular morphology, so alternative surgical techniques must be kept in
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mind.21,40-42 Bypass strategies for PICA aneurysms depend on aneurysm location, and include (i)
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P3-P3 PICA-PICA bypass, (ii) reimplantation of PICA into the V4 segment of the vertebral
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artery, (iii) PICA re-anastomosis after aneurysm excision, and (iv) high-flow aneurysm bypass
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using an interposition graft. In a 2016 case series by Abla and colleagues, 35 patients who
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underwent inracranial-intracranial (IC-IC) bypass of a PICA aneurysm were evaluated.42 The
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most common bypass method was a P3-P3 anastomosis, and 94% of overall bypasses remained
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patent. In general, aneurysm clipping and bypass procedures are more favorable than
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deconstructive approaches that sacrifice the PICA, such as coil occlusion or proximal PICA
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clipping. In distal segment PICA aneurysms, however, surgical PVO can be considered as a last
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resort, since most brainstem perforators arise from the first three PICA segments (VPJ, AM, LM)
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and will not be affected.43
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Certain aneurysms may be more suitable for microsurgical treatment. Rodriguez-
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Hernandez and Lawton found that treatment of PICA aneurysms in the anterior medullary zone
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required a route traversing the cranial nerves and thus had higher morbidity, whereas aneurysms
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completely outside the vagoaccessory triangle could be approached with minimal morbidity.37
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The choice of microsurgical clipping may also be determined by the rupture status of the
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aneurysm, as a high degree of surgical morbidity has been identified with ruptured PICA
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aneurysms.31 In our experience, aneurysms of the AM segment, that are intimately associated
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with brainstem perforators, as well as recurrent aneurysms are more suitable for microsurgical
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treatment.
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Endovascular Treatment The endovascular management of PICA aneurysms, both ruptured and unruptured, avoids the potential morbidity associated with surgical approaches. As utilized in the rest of the
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intracranial circulation, coil embolization is the primary endovascular method by which PICA
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aneurysms are treated.5,14,22,44 While stand-alone coiling may be suitable for many saccular PICA
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aneurysms with narrow necks, other endovascular techniques, such as BAC and SAC, may be
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necessary depending on the aneurysm anatomy as well as the PICA origin, distal course of the
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artery, and the vertebral artery.12,15,18,25 Although flow diversion (FD) has been used with
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increasing safety in the vertebrobasilar circulation,45 some have questioned its use for VA-PICA
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aneurysms given that the PICA, an end vessel usually without significant collaterals, may keep
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the proximal aspect of the aneurysm patent.46 A similar problem has been identified with FD for
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ICA aneurysms arising at the junction with a fetal PCA. The only patient in our series treated
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with FD had a recurrence, likely for this reason. Although we have used FD increasingly for
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fusiform VB aneurysms in our practice, we have seldom used it for VPJ aneurysms.
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Endovascular PVO has been used in cases of fusiform, dissecting, and other
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morphologically complex PICA aneurysms, especially of distal segments.16,24,26 For dissecting
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PICA aneurysms, occlusion of both the aneurysm itself and the proximal parent artery is
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recommended in order to secure the point of intimal injury.10 PVO is also a good option for poor
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clinical grade patients following aneurysm rupture.9,11 Unilateral PICA sacrifice is rarely
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associated with consequent infarction, and if infarction does occur morbidity is minimal.4,6,7
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With that said, it is essential that PVO is performed distal to the proximal segments where vital
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brainstem perforators originate.47 A PICA with an extracranial origin may be sacrificed more
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success using Onyx for distal PICA aneurysms with preservation of the proximal PICA.24 Case
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et al advocated for PVO of distal PICA aneurysms associated with cerebellar AVMs using liquid
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embolic agents.27
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Our approach favors endovascular management for both ruptured and unruptured
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aneurysms, although the majority of our patients presented with SAH limiting an analysis based
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on rupture status. We tended to utilize non-PVO endovascular treatment for VA-PICA junction
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aneurysms and PVO for distal, fusiform and dissecting aneurysms. Although we had a low rate
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of distal ischemia related to PVO, bypass should be kept in mind for distal and atypical PICA
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aneurysms that are associated with a large PICA that supplies a large territory of cerebellum. As
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with other intracranial aneurysms, incomplete occlusion, recurrence and retreatment are always
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concerns after endovascular treatment of PICA aneurysms and has been reported to be as high as
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30%.22 In our series the recurrence and retreatment rates were 23.3% and 20.0%. This should be
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kept in mind when choosing a treatment modality.
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Multimodality Treatment
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Many of the previous reports on PICA aneurysms have focused either on surgical or endovascular treatment. PICA aneurysms, however, are unique in that they span a wide range of
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morphologies, sizes, and anatomic locations relative to the vessel origin. Therefore, it is
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necessary to take a multimodality approach. Bohnstedt et al. published the largest series thus far
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evaluating both microsurgical and endovascular treatments in 102 PICA aneurysms.1 They
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determined that microsurgical treatment was more common for both saccular and fusiform
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aneurysms, whereas endovascular techniques tended to be preferred for dissecting aneurysms.
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greater rate of complications in the subgroup of patients with proximal PICA aneurysms who
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underwent surgical clipping. The rate of new postoperative deficits was 41% in patients treated
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surgically (both ruptured and unruptured aneurysms), compared to 16% in patients who
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underwent endovascular treatment. Overall outcomes at discharge, 6 months, and 1 year,
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however, did not differ significantly between the two groups.
Sejkorová et al evaluated 81 PICA aneurysms that were treated over a 15-year period and
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found comparable results for microsurgical versus endovascular management, a higher
324
recurrence rate for aneurysms treated with endovascular management, and clinical outcomes
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predicted best by admission clinical status.48 Cho et al recently advocated for multimodality
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management of proximal PICA aneurysms.49
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In a 2016 meta-analysis, Petr and colleagues assessed the use of both surgical and endovascular modalities in 796 PICA aneurysms from 29 case series.2 Again, surgical
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management was associated with a significantly higher rate of perioperative morbidity, with no
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overall long-term differences in clinical outcome between the two general treatment strategies.
331
However, they did note a significantly higher rate of aneurysm recurrence among PICA
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aneurysms treated with endovascular techniques (8.1%, compared to 1.1% of surgically treated
333
aneurysms). Surgical and endovascular management achieved similar safety and efficacy results
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for both proximal and distal PICA aneurysms. PVO was more commonly used for distal, rather
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than proximal aneurysms. Endovascular PVO more often resulted in perioperative stroke.
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Limitations
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Our study is limited by its retrospective design and small number of patients included. Given these limitations, it is difficult to make definitive conclusions regarding the trends
340
identified. Further, endovascular treatment is constantly evolving and treatment strategies have
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changed compared to five years ago as technology has improved. We restricted the population to
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the last 5 years to mitigate this limitation.
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Conclusion
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Our five-year modern experience highlights the diversity of PICA aneurysms and the need for multimodality paradigms to treat them successfully. The AM segment has the highest
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recurrence rate. PVO is a reasonable option for aneurysms distal to the AM segment and rarely
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results in clinically meaningful ischemia. With aggressive management, the majority of patients
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ultimately have a good clinical outcome. A full armamentarium of cerebrovascular specialists
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and techniques are necessary to treat these complex aneurysms.
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Disclosure: The authors report no conflict of interest concerning the materials or methods used
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in this study or the findings specified in this paper. None of the conflicts of interest listed below
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had any influence on this work but are being listed for completeness. •
Thomas Oxley is the founder and shareholder of Synchron.
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•
Reade De Leacy is a consultant to DFine and Medical Metrics.
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•
Johanna Fifi is a consultant to Microvention and Penumbra and holds a grant from
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Stryker.
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•
Aman Patel is a consultant to Penumbra and Medtronic/Covidien
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•
Dr. Mocco receives research funding support for ongoing clinical trials from Stryker
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Neurovascular, Penumbra, Medtronic Neurovascular, and Microvention. He is an
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investor in Blockade Medical, TSP and Cerebrotech. He is a consultant for TSP,
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Cerebrotech, Rebound, Pulsar, and Endostream.
•
We would like to acknowledge Jill Gregory for her artwork in Figures 1 and 9.
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Acknowledgements
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References
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Roy D, Milot G, Raymond J. Endovascular treatment of unruptured aneurysms. Stroke; a journal of cerebral circulation. 2001;32(9):1998-2004. Spetzler RF, McDougall CG, Zabramski JM, et al. The Barrow Ruptured Aneurysm Trial: 6-year results. J Neurosurg. 2015;123(3):609-617. Singh RK, Behari S, Kumar V, Jaiswal AK, Jain VK. Posterior inferior cerebellar artery aneurysms: Anatomical variations and surgical strategies. Asian J Neurosurg. 2012;7(1):2-11. Mascitelli JR, Ben-Haim S, Paramasivam S, Zarzour HK, Rothrock RJ, Bederson JB. Association of a Distal Intradural-Extracranial Posterior Inferior Cerebellar Artery Aneurysm With Chiari Type I Malformation: Case Report. Neurosurgery. 2015;77(4):E660-665; discussion E665. Foster MT, Herwadkar A, Patel HC. Posterior Inferior Cerebellar Artery/Vertebral Artery Subarachnoid Hemorrhage: A Comparison of Saccular vs Dissecting Aneurysms. Neurosurgery. 2017. Kawashima M, Takase Y, Matsushima T. Surgical treatment for vertebral arteryposterior inferior cerebellar artery aneurysms: special reference to the importance of the cerebellomedullary fissure dissection. J Neurosurg. 2013;118(2):460-464. D'Ambrosio AL, Kreiter KT, Bush CA, et al. Far lateral suboccipital approach for the treatment of proximal posteroinferior cerebellar artery aneurysms: surgical results and long-term outcome. Neurosurgery. 2004;55(1):39-50; discussion 50-34. Rodriguez-Hernandez A, Lawton MT. Anatomical triangles defining surgical routes to posterior inferior cerebellar artery aneurysms. J Neurosurg. 2011;114(4):10881094. Viswanathan GC, Menon G, Nair S, Abraham M. Posterior inferior cerebellar artery aneurysms: operative strategies based on a surgical series of 27 patients. Turk Neurosurg. 2014;24(1):30-37. Horowitz M, Kopitnik T, Landreneau F, et al. Posteroinferior cerebellar artery aneurysms: surgical results for 38 patients. Neurosurgery. 1998;43(5):1026-1032. Lawton MT, Hamilton MG, Morcos JJ, Spetzler RF. Revascularization and aneurysm surgery: current techniques, indications, and outcome. Neurosurgery. 1996;38(1):83-92; discussion 92-84. Kalani MY, Ramey W, Albuquerque FC, et al. Revascularization and aneurysm surgery: techniques, indications, and outcomes in the endovascular era. Neurosurgery. 2014;74(5):482-497; discussion 497-488. Abla AA, McDougall CM, Breshears JD, Lawton MT. Intracranial-to-intracranial bypass for posterior inferior cerebellar artery aneurysms: options, technical challenges, and results in 35 patients. J Neurosurg. 2016;124(5):1275-1286. Liew D, Ng PY, Ng I. Surgical management of ruptured and unruptured symptomatic posterior inferior cerebellar artery aneurysms. Br J Neurosurg. 2004;18(6):608-612. Mukonoweshuro W, Laitt RD, Hughes DG. Endovascular treatment of PICA aneurysms. Neuroradiology. 2003;45(3):188-192. Natarajan SK, Lin N, Sonig A, et al. The safety of Pipeline flow diversion in fusiform vertebrobasilar aneurysms: a consecutive case series with longer-term follow-up from a single US center. J Neurosurg. 2016;125(1):111-119. Kan P, Srinivasan VM, Mbabuike N, et al. Aneurysms with persistent patency after treatment with the Pipeline Embolization Device. J Neurosurg. 2016:1-5.
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Lister JR, Rhoton AL, Jr., Matsushima T, Peace DA. Microsurgical anatomy of the posterior inferior cerebellar artery. Neurosurgery. 1982;10(2):170-199. Sejkorova A, Petr O, Mulino M, et al. Management of posterior inferior cerebellar artery aneurysms: What factors play the most important role in outcome? Acta Neurochir (Wien). 2017;159(3):549-558. Cho KC, Kim YB, Suh SH, Joo JY, Hong CK. Multidisciplinary management for the treatment of proximal posterior inferior cerebellar artery aneurysms. Neurological research. 2017;39(5):403-413.
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Figure 1: PICA Anatomy and Aneurysms: The PICA anatomy is demonstrated including the
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VA-PICA junction followed by the 5 segments: anterior medullary (AM), lateral medullary
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(LM), tonsillomedullary (TM), telovelotonsillar (TVT), and cortical branches (CB). Figure by
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Jill Gregory. Printed with permission of ©Mount Sinai Health System.
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Figure 2: VA – PICA Junction: A patient with subarachnoid hemorrhage who was found to
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have both a basilar tip aneurysm and a saccular aneurysm arising at the origin of the PICA from
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the right vertebral artery (a). The vertebral artery (v), basilar artery (b), PICA (p), and aneurysm
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(arrow) are labeled. The aneurysm neck was incorporated into the origin of PICA. Therefore the
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aneurysm was treated with balloon assisted coiling (b). The balloon microcatheter and microwire
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(arrowhead) can be seen supporting the PICA and the coil mass within the aneurysm (arrow). A
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delayed angiogram demonstrated complete aneurysm occlusion (c).
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Figure 3: Anterior Medullary Segment: A patient with a ruptured fusiform aneurysm (arrow)
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of the anterior medullary segment of the right PICA (a). Given the fusiform nature of the
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aneurysm and proximity to the brainstem perforators, the decision was made to proceed with
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microsurgical clipping via a right far lateral suboccipital craniectomy and C1 laminectomy. The
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aneurysm (arrow) can be seen distal to the vertebral artery (v), arising from the proximal PICA
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(p), inferior to the cerebellum (c), and lateral to the brainstem (bs). The aneurysm was secured
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with a bayonetted clip (b). The postoperative angiogram demonstrated complete aneurysm
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occlusion with no evidence of PICA stenosis (c).
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Figure 4: Lateral Medullary Segment: A patient with a ruptured dissecting aneurysm (arrow)
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of the lateral medullary segment of the right PICA (a). In this case the aneurysm arose distal to
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the brainstem perforators, so the patient was treated with parent vessel occlusion using coils (b).
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extracranial, saccular PICA aneurysm (arrow) that was treated with coiling (a). The patient
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presented again 1 month later with symptoms from a Chiari I malformation and tonsillar ectopia
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and marked hydromyelia that appeared to be exacerbated by the coil mass (arrow; b). The patient
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was re-treated with a suboccipital craniectomy, C1-2 laminectomy, aneurysm trapping and
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excision (e-f), end-to-end PICA anastomosis, and expansile duraplasty (c-d). The coiled
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aneurysm (arrow) can be seen arising from the caudal loop of PICA (p) indenting the posterior
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cervical spinal cord (sc), inferior to the cerebellar tonsils (t). Post-operative angiogram
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demonstrated no evidence of residual aneurysm, a patent bypass, and shortening of the
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previously-elongated PICA (e). An MRI performed four months after surgery demonstrated
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interval elevation of the cerebellar tonsils above the foramen magnum and marked involution of
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the hydromyelia (f). Content similar to previously published material (Neurosurgery. 2015
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Oct;77(4):E660-5). Printed with permission from Wolters Kluwer Health, Inc (License number
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3998320582001).
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Figure 6: Telovelotonsillar Segment: A patient with a small vermian hematoma who was found
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to have a right cerebellar (tentorial) AVM (arrowhead) with a fusiform in-flow aneurysm (arrow)
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arising from the telovelotonsillar (TVT) segment of PICA (a). The aneurysm was the source of
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hemorrhage and was treated with coil occlusion of the superior division of the PICA without
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evidence of cerebellar infarction. Two weeks later the patient was taken to the operating room
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for resection of the AVM (b). The venous trunk (thick arrow) seen to enter the transverse sinus
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(t) contains a mix of flow from the arterialized vein medially (arrow) and the normal vein
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laterally (arrowhead). The cerebellar surface (c) appeared relatively normal with the AVM deep
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to it. A final angiogram demonstrated no residual aneurysm or AVM (c).
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initial angiogram did not demonstrate a vascular lesion. Repeat angiogram 1 week after
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presentation demonstrated a distal, cortical PICA aneurysm (arrow; a). Given its distal location,
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the aneurysm was treated with parent vessel occlusion (PVO) using a combination of nBCA and
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coilsaarow; b resulting in complete aneurysm occlusion (c). The patient did not have an MRI but
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there was no infarction on CT scan.
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Figure 8: Multimodality Treatment of PICA Aneurysms: A comprehensive approach should
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be taken for PICA aneurysms, including an assortment of endovascular and microsurgical
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treatments and re-treatments. Figure by Jill Gregory. Printed with permission of ©Mount Sinai
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Health System.
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Figure 10: Treatment Algorithm
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Table 1: Clinical Information
Hunt Hess Grade 1 2 3 4 5
3 4 11 2 5
12.0 16.0 44.0 8.0 20.0
SAH-Associated Cerebellar ICH
6
24.0
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83.3 13.3 3.3
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CLINICAL PRESENTATION SAH 25 Incidental Finding 4 Family History of Aneurysms 1
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Table 1. CLINICAL INFORMATION Category No. % DEMOGRAPHICS Patients 30 Aneurysms 30 Female 23 76.7 Male 7 23.3 Age Range 17-87 years Average Age 55.9 Years
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SAH, subarachnoid hemorrhage; ICH, intracerebral hemorrhage
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Table 2: Aneurysm Information
VA-PICA Junction Anterior Medullary Lateral Medullary Tonsillomedullary Telovelotonsillar Cortical Branch
8 7 3 1 5 6
26.7 23.3 10.0 3.3 16.7 20.0
ANEURYSM TYPE 15 14 1
50.0 46.7 3.3
Saccular Fusiform Dissecting
7
23.3
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ANEURYSM ORIGIN Right Side 16 Left Side 14
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Table 2. ANEURYSM SITE & NATURE Category No. % VESSEL & ANEURYSM ORIGIN PICA ORIGIN Intradural 28 93.3 Extradural 2 6.7
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ANEURYSM DIMENSIONS Max Diameter 4.91 mm Average. Diameter 4.08 mm Neck 2.59 mm 3 Volume 55.7 mm Aspect Ratio 2.27
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VA-PICA, vertebral artery – posterior inferior cerebellar artery
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Table 3: Treatment Information Table 3. TREATMENT INFORMATION Category No. INITIAL TREATMENT ELECTED Surgical Clip Reconstruction 6 Parent Vessel Occlusion 2 Endovascular Stand Alone Coiling 13 Balloon Assisted Coiling 1 Stent Assisted Coiling 1 Flow Diversion 1 Parent Vessel Occlusion 6
43.3 3.3 3.3 3.3 20.0
SUPPLEMENTAL TREATMENT Suboccipital Craniectomy after EVT 1 AVM resection 5
4.5 71.4
2
10.0 3.3 3.3 3.3
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60.0 30.0 10.0
RECURRENCE & RETREATMENT Recurrence 7 Retreatment 6 Clip Reconstruction 4 Bypass (End-To-End) 1 Stand Alone Coiling 1
23.3 20.0 66.7 16.7 16.7
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INITIAL OCCLUSION CLASSIFICATION Complete Occlusion 18 Neck Remnant 8 Residual Aneurysm 3
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COMPLICATIONS OF TREATMENT Procedural Complications 3 Extravasation 1 Vessel Compromise 1 Coil Prolapse 1
%
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Table 4: Clinical Information Table 4. Clinical Outcomes Category No. DISCHARGE mRS Good (0 – 2) 13 Poor (3 – 6) 17
43.3 56.7
FOLLOW-UP mRS Good (0 – 2) 22 Poor (3 – 6) 4
84.6 15.4
Death
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Table 5: Associations with Outcome Table 5
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Clinical Outcome Good Poor P Value (n=22) (n=4) 53.2 62.3 0.118 0.0896 19 (86.4) 2 (50.0) 3 (13.6) 2 (50.0) 17 (77.3) 4 (100) 0.008 15 (88.2) 1 (25.0) 2 (11.8) 3 (75.0) 0.991 6 (27.3) 1 (25.0) 6 (27.3) 1 (25.0) 1 (4.6) 0 (0.0) 1 (4.6) 0 (0.0) 4 (18.2) 1 (25.0) 4 (18.2) 1 (25.0) 0.867 12 (54.6) 2 (50.0) 10 (45.5) 2 (50.0) 11 (50.0) 1 (25.0) 0.356
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Angiographic Outcome Non-Recurrent Recurrent P Value (n=23) (n=7) Age 57.6 50.4 0.054 Gender 0.708 Female 18 (78.3) 5 (71.4) Male 5 (21.7) 2 (28.6) SAH 19 (82.6) 6 (85.7) 0.847 Hunt Hess 0.739 Good (I – III) 14 (73.7) 4 (57.1) Poor (IV – V) 5 (26.3) 2 (28.6) Location 0.050 VPJ 7 (30.4) 1 (14.3) AM 3 (13.0) 4 (57.1) 0.016* LM 3 (13.0) 0 (0.0) TM 0 (0.0) 1 (14.3) TVT 4 (17.4) 1 (14.3) Cortical 6 (26.1) 0 (0.0) Location 0.195 Proximal 10 (43.5) 5 (71.4 Distal 13 (56.5) 2 (28.6) Saccular 11 (47.8) 4 (57.4) 0.666 Treatment 0.896 Surgical 6 (26.1) 2 (28.5) EVT 17 (73.9) 5 (71.4) *AM compared to all other locations
6 (27.3) 16 (72.7)
2 (50.0) 2 (50.0)
0.365
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SAH = subarachnoid hemorrhage; VPJ = vertebral PICA junction; AM = anterior medullary; LM = lateral medullary; TM = tonsillomedullary; TVT = telovelotonsillar; EVT = endovascular treatment
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Highlights: •
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Our five-year modern experience highlights the diversity of PICA aneurysms and the need for multimodality paradigms to treat them successfully. The AM segment has the highest recurrence rate. Aggressive management is warranted given that the majority of patients can have a good neurological outcome.
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PICA – posterior inferior cerebellar artery SAH – subarachnoid hemorrhage VA – vertebral artery AM – anterior medullary PVO – parent vessel occlusion AVM – arteriovenous malformation VPJ – vertebral artery PICA junction EMR – electronic medical record DSA – digital subtraction angiography LM – lateral medullary TM – tonsillomedullary TVT – telovelotonsillar CB – cortical branches mRS – modified Rankin Scale CMF – cerebellomedullary fissure FD – flow diversion BAC – balloon-assisted coiling SAC – stent-assisted coiling
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Abbreviations:
S1878-8750(17)31124-5
DOI:
10.1016/j.wneu.2017.07.024
Reference:
WNEU 6086
To appear in:
World Neurosurgery
Received Date: 13 May 2017 Revised Date:
3 July 2017
Accepted Date: 6 July 2017
Please cite this article as: Mascitelli JR, Yaeger K, Wei D, Kellner CP, Oxley TJ, De Leacy RA, Fifi JT, Patel AB, Naidich TP, Bederson JB, Mocco J, Multimodality Treatment of Posterior Inferior Cerebellar Artery Aneurysms, World Neurosurgery (2017), doi: 10.1016/j.wneu.2017.07.024. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT Multimodality Treatment of PICA Aneurysms 1
Title: Multimodality Treatment of Posterior Inferior Cerebellar Artery Aneurysms
2 Authors: Justin R. Mascitelli, MD1; Kurt Yaeger, MD1; Daniel Wei, BS1; Christopher P.
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Kellner, MD1; Thomas J. Oxley, MD, PhD1,; Reade A. De Leacy, MD1; Johanna T. Fifi, MD1;
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Aman B. Patel, MD2; Thomas P. Naidich, MD3; Joshua B. Bederson, MD1; J Mocco, MD, MS1
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Department of Neurosurgery, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical School,
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Boston, MA, USA 3
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Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
11 Correspondence To:
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Justin Mascitelli, MD
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Mount Sinai Health System
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Department of Neurosurgery
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1450 Madison Avenue
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Klingenstein Clinical Center, 1-North
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New York, New York, USA 10029
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Tel: 212-241-3400
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Fax: 646-537-2299
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Email: [email protected]
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Key Words: aneurysm, clipping, coiling, PICA
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Running Title: Multimodality Treatment of PICA Aneurysms
25 Disclosure: The authors report no conflict of interest concerning the materials or methods used
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in this study or the findings specified in this paper. None of the conflicts of interest listed below
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had any influence on this work but are being listed for completeness.
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Thomas Oxley is the founder and shareholder of Synchron.
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Reade De Leacy is a consultant to DFine and Medical Metrics.
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Johanna Fifi is a consultant to Microvention and Penumbra and holds a grant from
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Stryker.
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Aman Patel is a consultant to Penumbra and Medtronic/Covidien
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Dr. Mocco receives research funding support for ongoing clinical trials from Stryker Neurovascular, Penumbra, Medtronic Neurovascular, and Microvention. He is an
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investor in Blockade Medical, TSP and Cerebrotech. He is a consultant for TSP,
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Cerebrotech, Rebound, Pulsar, and Endostream.
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Previous presentations: None
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ACCEPTED MANUSCRIPT Multimodality Treatment of PICA Aneurysms Abstract
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OBJECT Posterior inferior cerebellar artery (PICA) aneurysms are heterogeneous, uncommon
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lesions that can be treated in many fashions. Many previous series have focused on a specific
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aneurysm subset or treatment paradigm. The aim of this study was to present a comprehensive
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approach for all PICA aneurysms and analyze outcomes by PICA location.
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METHODS All PICA aneurysms treated from 2012 until present were reviewed retrospectively
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and classified by location. Angiographic and clinical outcome were assessed.
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RESULTS We identified 30 patients (average age 56 years, female 76.7%, subarachnoid
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hemorrhage 83.3%) with 30 aneurysms (saccular 50.0%) who underwent 36 treatments.
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Locations included: VA-PICA junction: 8; anterior medullary (AM): 7; lateral medullary: 3;
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tonsillomedullary: 1; telovelotonsillar: 5; and cortical: 6. Treatments included clipping: 6;
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trapping: 2; coiling: 13; balloon-assisted coiling: 1; stent-assisted coiling: 1; flow diversion: 1;
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and endovascular parent vessel occlusion (PVO): 6. There were 3 procedural complications.
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Recurrence and retreatment rates were 23.3% and 20.0%, respectively. Retreatments included
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coiling: 1; clipping: 4; and bypass: 1. Seven patients had an associated cerebellar AVM, of which
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5 have undergone resection. Good clinical outcome was achieved in 43.3% at discharge and
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84.6% at follow-up (average 10.7 months). Aneurysms distal to the AM segment were more
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likely to occur in older patients (P = 0.007), with cerebellar AVMs (P = 0.031), and to be treated
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with PVO (P = .001). Recurrences were more common for AM segment aneurysms (P = 0.016).
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Poor outcome was associated with poor SAH grade (P = 0.010), not aneurysm morphology
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(P=0.356), location (P = 0.867) or treatment type (P = 0.365).
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CONCLUSIONS Our five-year modern experience highlights the diversity of PICA aneurysms
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and the need for multimodality paradigms to treat them successfully. The AM segment has the
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highest recurrence rate. Aggressive management is warranted given that the majority of patients
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can have a good neurological outcome.
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Posterior inferior cerebellar artery (PICA) aneurysms are uncommon lesions that account for approximately 0.5 – 3% of all intracranial aneurysms.1,2 They are highly diverse and their
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sites of origin span from the vertebral artery PICA junction (VPJ) to anywhere along the length
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of the PICA (Figure 1). They may be saccular, dissecting, or fusiform. They may be treated
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utilizing a broad range of microsurgical and endovascular techniques. Although there have been
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a number of published PICA aneurysm series, frequently these series focus on only one
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population of PICA aneurysms (e.g. distal segment) or only one treatment modality (e.g.
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endovascular therapy).3-29 Our modern series highlights the variety of treatment modalities
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available, the efficacy of these treatments for specific aneurysm locations, and the importance of
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treating complex aneurysms at an academic center with specialists in open cerebrovascular,
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endovascular, and neurointensive care.
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Following approval from the Institutional Review Board, retrospective review of
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aneurysms treated over the five-year period from April 2012 to April 2017 disclosed 30 patients
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with 30 PICA aneurysms who underwent 36 interventions. A waiver of consent was obtained to
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perform this retrospective review. Demographic information was obtained from the electronic
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medical record (EMR). Mode of presentation was recorded for all aneurysms and correlated with
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clinical presentation and outcome. Concurrent medical conditions such as trauma, connective
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tissue disease, and drug use were recorded. Hunt Hess score was used for subarachnoid
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hemorrhage (SAH) grade, and poor grade was defined as IV and V. All SAH patients received
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standard Neurosurgical ICU management for at least 2 weeks.
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ACCEPTED MANUSCRIPT Multimodality Treatment of PICA Aneurysms Aneurysms were evaluated on digital subtraction angiography (DSA). By location,
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aneurysms arising at the vertebral artery (VA) – PICA junction (VPJ) and aneurysms arising
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within the 5 segments of PICA (Figure 1): anterior medullary (AM), lateral medullary (LM),
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tonsillomedullary (TM), telovelotonsillar (TVT), and cortical branches (CB) were included in the
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study group. Aneurysms of the VPJ and AM segment were defined as proximal and all others
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distal.14 By type, aneurysms accepted into the study group included saccular and atypical (e.g.
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fusiform and dissecting) aneurysms, and feeding artery aneurysms associated with cerebellar
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AVMs. Intranidal aneurysms were excluded from the study. Aneurysm sizes were measured in
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three dimensions at the time of treatment and recorded in the operative report. The side and
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origin of the affected PICA with respect to the dura were noted in each case.
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For each aneurysm, the treatment type and any procedural complications were
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determined from the operative reports. Treatment for a given aneurysm was based on consensus
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opinion from members of a comprehensive cerebrovascular team, consisting of neurosurgeons,
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neurologists, neuroradiologists, and intensive care specialists. Except in emergency situations,
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cases were typically presented during a daily conference, and treatment was decided after an
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open discussion of risks, benefits, and alternatives of each treatment modality. For patients that
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underwent PVO, postoperative MRI and CT were evaluated for ischemia in the PICA territory.
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The extent of initial aneurysm occlusion was graded utilizing the 3 step Raymond scale:30 Grade
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1 (complete aneurysm occlusion), Grade 2 (residual aneurysm neck), Grade 3 (residual aneurysm
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dome). Follow-up information included any evidence of aneurysm recurrence, any need for re-
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treatment and the type of retreatment selected. Clinical outcome was retrospectively derived
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from the EMR based on the Modified Rankin Scale (mRS). Poor outcome was defined as mRS 3
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– 6.
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Data for PICA aneurysms were assessed by location, angiographic outcome, and clinical outcome. Comparisons were made between the following patient groups: 1) proximal vs. distal
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PICA aneurysm, 2) non-recurrent vs. recurrent, 3) good vs. poor clinical outcome. Continuous
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variables are presented as mean±SD and were compared between groups using Student t tests.
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Categorical variables were compared between groups using χ2 tests. The Mann-Whitney test was
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used to compare age between groups. All reported P values are two-sided with α = 0.05.
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Statistical analyses were performed using the R language for statistical programming (R
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Foundation for Statistical Computing; Vienna, Austria).
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Results
The final study group included 40 patients with 40 PICA aneurysms who underwent 36 separate treatments (Table 1). Most patients were female (76.7%). The average age at
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presentation was 56 years. Most patients (83.3%) presented with subarachnoid hemorrhage
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(SAH). Other presentations included incidental imaging finding (n = 4), and positive family
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history (n=1). The majority of SAH patients (72%) had an initial good Hunt Hess score (I – III).
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Concurrent cerebellar ICH was present in 24% of cases. No patients had a history of trauma,
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connective tissue disease or drug abuse that would predispose to non-saccular aneurysm
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formation.
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The origins of the PICA aneurysms were widely distributed (Table 2; Figures 2 – 7):
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VPJ: 8, AM: 7, LM: 3; TM: 1; TVT: 5; and CB: 6. There was an equal distribution of saccular
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versus atypical aneurysms: 15 (50%) were saccular in morphology, 14 (46.7%) were fusiform,
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and one (3.3%) was a dissecting aneurysm. Non-saccular morphology was associated with
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presence of a cerebellar ICH (P=0.006). Seven aneurysms (23.3%) were inflow aneurysms
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of left (46.7%) and right (53.3%) sided aneurysms. The average maximum dome diameter was
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4.91 mm. The PICA origin was intradural in 93.3% of cases. Both aneurysms with extradural
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PICA origin happened to be fusiform aneurysms of the AM segment. In comparison to proximal
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aneurysms, those distal to the AM segment were associated with older patients (62.3 vs. 49.6
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years, P = 0.007) who harbored cerebellar AVMs (40.0% vs 6.67%, P =0.031).
Primary treatments (Table 3) included microsurgical clipping: 6; surgical trapping: 2;
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stand-alone coiling: 13; balloon-assisted coiling (BAC): 1; stent-assisted coiling (SAC): 1; flow
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diversion (FD)-assisted coiling: 1; and endovascular parent vessel occlusion (PVO): 6.
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Endovascular PVO was performed with coils alone: 2; N-butyl cyanoacrylate (nBCA; Cordis
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Microvascular, Inc., New Brunswick, NJ): 1; Onyx (Medtronic): 2, or a combination of
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materials: 1. Six of the 8 VPJ aneurysms were managed with non-PVO endovascular techniques.
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Four of the 7 aneurysms of the AM segment were treated with clipping. In comparison to
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proximal aneurysms, those distal to the AM segment were more likely to be treated with any
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type of PVO (53.3% vs 0%, P =0 .001). Non-saccular aneurysms were also more likely to be
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treated with PVO (53.3% vs. 0.0%, P=0.001). Of the patients treated with PVO, 25% had
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radiographic ischemic changes in the PICA territory. In addition to aneurysm treatment, one
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patient required a suboccipital craniectomy following aneurysm embolization due to mass effect
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in the posterior fossa and 5 patients went on the have AVM resection (with two more planned at
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the time of writing this manuscript).
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The initial occlusion classification was as follows: complete occlusion (60.0%), neck
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remnant (30.0%), and residual aneurysm (10.0%). The aneurysm recurrence and retreatment
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rates were 23.3% and 20.0%, respectively. Recurrences were seen after initial treatment by
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ACCEPTED MANUSCRIPT Multimodality Treatment of PICA Aneurysms coiling (4), FD (1) and clipping (2). No recurrences were seen after PVO. Recurrences were
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more likely to occur for AM segment aneurysms versus other locations (57.1% vs 15.8%, P =
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0.016). The 4 AM recurrences occurred after coiling (2) and clipping (2). Both of the
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microsurgical AM recurrences (one early and one delayed) occurred in fusiform AM aneurysms
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in which the most diseased portion of the vessel and rupture site was clipped initially but an
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adjacent portion of the vessel ultimately enlarged. One of these recurrences was retreated with
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repeat clipping and the other was retreated with coiling. In total, retreatments included coiling: 1;
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clipping: 4; and bypass: 1. The bypass was performed for a unique case in which the patient had
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an exacerbated chiari malformation secondary to a coil mass, published previously as a case
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report33. The majority of the retreatments (80%) involved changing the approach from
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endovascular to surgical therapy or visa versa. Including the retreatments, 9 different treatment
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types were employed.
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during endovascular treatment. These were vessel perforation in 1 case and vessel compromise in
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two. These complications did not lead to morbidity or mortality. There were no intraoperative
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complications during microsurgical clipping. Three patients experienced delayed complications
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following microsurgical treatment: one with a postoperative abscess requiring surgical
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evacuation, and two with persistent lower cranial nerve dysfunction at follow-up, one mild and
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one severe. In addition, two patients had delayed complications related to VP shunting. The rate
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of good neurological outcome (mRS 0-2) at discharge was 43.3%. The rate of good neurological
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outcome at last known follow-up (average 11 months) was 86.7%. Two patients in this series
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died from complications of the initial SAH. Poor outcome was associated with poor SAH grade
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(P = 0.008). Clinical outcome was not influenced by aneurysm morphology (P=0.356), location
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(P = .867) or treatment type (P = .365).
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Discussion
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The most important finding of our modern series is that a multidisciplinary team is
necessary to treat this heterogeneous group of aneurysms (Figure 8). In 30 patients/aneurysms
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undergoing 36 treatments, we found 3 different aneurysm types, 6 different aneurysm locations,
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9 different treatment strategies (both surgical and endovascular), and an 80% treatment strategy
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change for recurrent aneurysms. Additionally, 83% of patients experience SAH requiring critical
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care management for a number of weeks. Therefore a cohesive team consisting of
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neurosurgeons, interventionalists, and intensivists is necessary to handle this diverse group of
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lesions.
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secondary to attempts to preserve brainstem perforators. This is a novel finding and this
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subgroup of PICA aneurysms may require closer follow-up. Secondly, PVO is a reasonable
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treatment option for distal PICA aneurysms and rarely results in clinically meaningful ischemia.
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Finally, although ruptured PICA aneurysms are notorious for causing poor clinical outcome,31
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our series demonstrate that the vast majority patients with PICA aneurysms have a good outcome
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at follow-up, frequently improved from discharge, and therefore aggressive management is
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warranted.
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PICA Aneurysm Anatomy
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PICA aneurysms are uncommon and account for 0.5-3% of all intracranial aneurysms.1,2 They are heterogeneous in both location and morphology. Although they can occur anywhere
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from the VA-PICA junction to the distal cortical branches of PICA, they most commonly arise
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from the VA-PICA junction.1,22,32 Less often, they occur in a distal PICA segment, accounting
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for approximately 15-30% of all PICA aneurysms.17 Interestingly, in our series, the breakdown
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between proximal and distal was equally matched. Of distal PICA aneurysms, the TVT segment
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has been reported to be the most common site of origin.3 We found that the cortical segment was
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the most common distal location.
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extracranial PICA aneurysms, usually associated with an extradural origin of PICA or caudal
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displacement of the TM segment.33 PICA aneurysms are more likely to have a fusiform
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morphology than other, non-PICA aneurysms.20,26 Dissecting PICA aneurysms have been found
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more typically to occur in distal PICA segments.19,26 Additionally, atypical aneurysms have been
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associated with worse clinical outcomes.34 In our series, half of the patients had saccular
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aneurysms and half atypical aneurysms. We did not find differences in radiographic our clinical
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outcome base on aneurysm morphology.
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Treatment Options
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Given the diversity of location and morphology amongst PICA aneurysms, no single
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treatment can be consistently employed. Microsurgical treatment options include clipping,
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trapping/PVO, resection, as well as a variety of bypasses procedures. Endovascular treatment
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options include stand-alone coiling, BAC, SAC, FD, or PVO with coils, liquid embolic material
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or both. Occasionally, a combination of both microsurgical and endovascular techniques is
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entirely on aneurysm morphology, location and surgeon/interventionalist comfort. Additionally,
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PICA aneurysms are frequently associated with cerebellar AVMs (23.3% in our series), which
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are ideally managed with surgical resection with or without preoperative embolization.
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Microsurgical Treatment
For proximal PICA aneurysms, the far lateral approach provides access to the cerebello-
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medullary fissure (CMF).1,35 There are many versions of the far lateral approach, but most
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involve a suboccipital craniectomy, C1 laminectomy, and resection of the medial portion of the
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occipital condyle (to varying degrees). When used for PICA aneurysms, this approach is
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associated with favorable outcomes, low postoperative morbidity, and no greater morbidity in
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comparison to craniotomies for posterior communicating aneurysms.36 Recently, Seoane et al
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published a surgical series utilizing the far lateral approach for PICA aneurysms without
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condylar resection.29 Rodriguez-Hernandez and Lawton described the vagoaccessory triangle,
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bordered medially by the medulla, laterally by the spinal accessory nerve (CN XI), and
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superiorly by the vagus nerve (CN X),37 as the anatomic corridor to reach PICA aneurysms. The
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triangle is subdivided into the supra- and infra-hypoglossal triangles by the hypoglossal nerve
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(CN XII). Further, the PICA origin will determine whether a VA-PICA junction aneurysm arises
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in the AM, LM, or TM zone. Identification of the extradural vertebral artery is essential for
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proximal control. Maintaining a caudal to rostral view beneath the cranial nerves rather than
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through them may reduce postoperative cranial nerve dysfunction.38 For aneurysms of more
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distal, cortical PICA segments, a midline suboccipital craniectomy is sufficient.39
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clipping.17,20,37,39 Compared to aneurysms in other location, PICA aneurysms are more likely to
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have a fusiform or non-saccular morphology, so alternative surgical techniques must be kept in
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mind.21,40-42 Bypass strategies for PICA aneurysms depend on aneurysm location, and include (i)
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P3-P3 PICA-PICA bypass, (ii) reimplantation of PICA into the V4 segment of the vertebral
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artery, (iii) PICA re-anastomosis after aneurysm excision, and (iv) high-flow aneurysm bypass
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using an interposition graft. In a 2016 case series by Abla and colleagues, 35 patients who
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underwent inracranial-intracranial (IC-IC) bypass of a PICA aneurysm were evaluated.42 The
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most common bypass method was a P3-P3 anastomosis, and 94% of overall bypasses remained
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patent. In general, aneurysm clipping and bypass procedures are more favorable than
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deconstructive approaches that sacrifice the PICA, such as coil occlusion or proximal PICA
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clipping. In distal segment PICA aneurysms, however, surgical PVO can be considered as a last
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resort, since most brainstem perforators arise from the first three PICA segments (VPJ, AM, LM)
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and will not be affected.43
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Certain aneurysms may be more suitable for microsurgical treatment. Rodriguez-
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Hernandez and Lawton found that treatment of PICA aneurysms in the anterior medullary zone
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required a route traversing the cranial nerves and thus had higher morbidity, whereas aneurysms
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completely outside the vagoaccessory triangle could be approached with minimal morbidity.37
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The choice of microsurgical clipping may also be determined by the rupture status of the
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aneurysm, as a high degree of surgical morbidity has been identified with ruptured PICA
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aneurysms.31 In our experience, aneurysms of the AM segment, that are intimately associated
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with brainstem perforators, as well as recurrent aneurysms are more suitable for microsurgical
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treatment.
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Endovascular Treatment The endovascular management of PICA aneurysms, both ruptured and unruptured, avoids the potential morbidity associated with surgical approaches. As utilized in the rest of the
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intracranial circulation, coil embolization is the primary endovascular method by which PICA
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aneurysms are treated.5,14,22,44 While stand-alone coiling may be suitable for many saccular PICA
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aneurysms with narrow necks, other endovascular techniques, such as BAC and SAC, may be
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necessary depending on the aneurysm anatomy as well as the PICA origin, distal course of the
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artery, and the vertebral artery.12,15,18,25 Although flow diversion (FD) has been used with
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increasing safety in the vertebrobasilar circulation,45 some have questioned its use for VA-PICA
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aneurysms given that the PICA, an end vessel usually without significant collaterals, may keep
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the proximal aspect of the aneurysm patent.46 A similar problem has been identified with FD for
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ICA aneurysms arising at the junction with a fetal PCA. The only patient in our series treated
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with FD had a recurrence, likely for this reason. Although we have used FD increasingly for
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fusiform VB aneurysms in our practice, we have seldom used it for VPJ aneurysms.
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Endovascular PVO has been used in cases of fusiform, dissecting, and other
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morphologically complex PICA aneurysms, especially of distal segments.16,24,26 For dissecting
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PICA aneurysms, occlusion of both the aneurysm itself and the proximal parent artery is
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recommended in order to secure the point of intimal injury.10 PVO is also a good option for poor
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clinical grade patients following aneurysm rupture.9,11 Unilateral PICA sacrifice is rarely
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associated with consequent infarction, and if infarction does occur morbidity is minimal.4,6,7
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With that said, it is essential that PVO is performed distal to the proximal segments where vital
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brainstem perforators originate.47 A PICA with an extracranial origin may be sacrificed more
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success using Onyx for distal PICA aneurysms with preservation of the proximal PICA.24 Case
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et al advocated for PVO of distal PICA aneurysms associated with cerebellar AVMs using liquid
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embolic agents.27
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Our approach favors endovascular management for both ruptured and unruptured
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aneurysms, although the majority of our patients presented with SAH limiting an analysis based
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on rupture status. We tended to utilize non-PVO endovascular treatment for VA-PICA junction
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aneurysms and PVO for distal, fusiform and dissecting aneurysms. Although we had a low rate
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of distal ischemia related to PVO, bypass should be kept in mind for distal and atypical PICA
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aneurysms that are associated with a large PICA that supplies a large territory of cerebellum. As
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with other intracranial aneurysms, incomplete occlusion, recurrence and retreatment are always
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concerns after endovascular treatment of PICA aneurysms and has been reported to be as high as
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30%.22 In our series the recurrence and retreatment rates were 23.3% and 20.0%. This should be
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kept in mind when choosing a treatment modality.
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Multimodality Treatment
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Many of the previous reports on PICA aneurysms have focused either on surgical or endovascular treatment. PICA aneurysms, however, are unique in that they span a wide range of
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morphologies, sizes, and anatomic locations relative to the vessel origin. Therefore, it is
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necessary to take a multimodality approach. Bohnstedt et al. published the largest series thus far
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evaluating both microsurgical and endovascular treatments in 102 PICA aneurysms.1 They
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determined that microsurgical treatment was more common for both saccular and fusiform
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aneurysms, whereas endovascular techniques tended to be preferred for dissecting aneurysms.
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greater rate of complications in the subgroup of patients with proximal PICA aneurysms who
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underwent surgical clipping. The rate of new postoperative deficits was 41% in patients treated
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surgically (both ruptured and unruptured aneurysms), compared to 16% in patients who
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underwent endovascular treatment. Overall outcomes at discharge, 6 months, and 1 year,
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however, did not differ significantly between the two groups.
Sejkorová et al evaluated 81 PICA aneurysms that were treated over a 15-year period and
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found comparable results for microsurgical versus endovascular management, a higher
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recurrence rate for aneurysms treated with endovascular management, and clinical outcomes
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predicted best by admission clinical status.48 Cho et al recently advocated for multimodality
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management of proximal PICA aneurysms.49
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In a 2016 meta-analysis, Petr and colleagues assessed the use of both surgical and endovascular modalities in 796 PICA aneurysms from 29 case series.2 Again, surgical
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management was associated with a significantly higher rate of perioperative morbidity, with no
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overall long-term differences in clinical outcome between the two general treatment strategies.
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However, they did note a significantly higher rate of aneurysm recurrence among PICA
332
aneurysms treated with endovascular techniques (8.1%, compared to 1.1% of surgically treated
333
aneurysms). Surgical and endovascular management achieved similar safety and efficacy results
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for both proximal and distal PICA aneurysms. PVO was more commonly used for distal, rather
335
than proximal aneurysms. Endovascular PVO more often resulted in perioperative stroke.
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Limitations
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Our study is limited by its retrospective design and small number of patients included. Given these limitations, it is difficult to make definitive conclusions regarding the trends
340
identified. Further, endovascular treatment is constantly evolving and treatment strategies have
341
changed compared to five years ago as technology has improved. We restricted the population to
342
the last 5 years to mitigate this limitation.
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343
345
Conclusion
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Our five-year modern experience highlights the diversity of PICA aneurysms and the need for multimodality paradigms to treat them successfully. The AM segment has the highest
347
recurrence rate. PVO is a reasonable option for aneurysms distal to the AM segment and rarely
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results in clinically meaningful ischemia. With aggressive management, the majority of patients
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ultimately have a good clinical outcome. A full armamentarium of cerebrovascular specialists
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and techniques are necessary to treat these complex aneurysms.
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Disclosure: The authors report no conflict of interest concerning the materials or methods used
353
in this study or the findings specified in this paper. None of the conflicts of interest listed below
354
had any influence on this work but are being listed for completeness. •
Thomas Oxley is the founder and shareholder of Synchron.
356
•
Reade De Leacy is a consultant to DFine and Medical Metrics.
357
•
Johanna Fifi is a consultant to Microvention and Penumbra and holds a grant from
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Stryker.
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•
Aman Patel is a consultant to Penumbra and Medtronic/Covidien
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•
Dr. Mocco receives research funding support for ongoing clinical trials from Stryker
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Neurovascular, Penumbra, Medtronic Neurovascular, and Microvention. He is an
362
investor in Blockade Medical, TSP and Cerebrotech. He is a consultant for TSP,
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Cerebrotech, Rebound, Pulsar, and Endostream.
•
We would like to acknowledge Jill Gregory for her artwork in Figures 1 and 9.
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Acknowledgements
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Roy D, Milot G, Raymond J. Endovascular treatment of unruptured aneurysms. Stroke; a journal of cerebral circulation. 2001;32(9):1998-2004. Spetzler RF, McDougall CG, Zabramski JM, et al. The Barrow Ruptured Aneurysm Trial: 6-year results. J Neurosurg. 2015;123(3):609-617. Singh RK, Behari S, Kumar V, Jaiswal AK, Jain VK. Posterior inferior cerebellar artery aneurysms: Anatomical variations and surgical strategies. Asian J Neurosurg. 2012;7(1):2-11. Mascitelli JR, Ben-Haim S, Paramasivam S, Zarzour HK, Rothrock RJ, Bederson JB. Association of a Distal Intradural-Extracranial Posterior Inferior Cerebellar Artery Aneurysm With Chiari Type I Malformation: Case Report. Neurosurgery. 2015;77(4):E660-665; discussion E665. Foster MT, Herwadkar A, Patel HC. Posterior Inferior Cerebellar Artery/Vertebral Artery Subarachnoid Hemorrhage: A Comparison of Saccular vs Dissecting Aneurysms. Neurosurgery. 2017. Kawashima M, Takase Y, Matsushima T. Surgical treatment for vertebral arteryposterior inferior cerebellar artery aneurysms: special reference to the importance of the cerebellomedullary fissure dissection. J Neurosurg. 2013;118(2):460-464. D'Ambrosio AL, Kreiter KT, Bush CA, et al. Far lateral suboccipital approach for the treatment of proximal posteroinferior cerebellar artery aneurysms: surgical results and long-term outcome. Neurosurgery. 2004;55(1):39-50; discussion 50-34. Rodriguez-Hernandez A, Lawton MT. Anatomical triangles defining surgical routes to posterior inferior cerebellar artery aneurysms. J Neurosurg. 2011;114(4):10881094. Viswanathan GC, Menon G, Nair S, Abraham M. Posterior inferior cerebellar artery aneurysms: operative strategies based on a surgical series of 27 patients. Turk Neurosurg. 2014;24(1):30-37. Horowitz M, Kopitnik T, Landreneau F, et al. Posteroinferior cerebellar artery aneurysms: surgical results for 38 patients. Neurosurgery. 1998;43(5):1026-1032. Lawton MT, Hamilton MG, Morcos JJ, Spetzler RF. Revascularization and aneurysm surgery: current techniques, indications, and outcome. Neurosurgery. 1996;38(1):83-92; discussion 92-84. Kalani MY, Ramey W, Albuquerque FC, et al. Revascularization and aneurysm surgery: techniques, indications, and outcomes in the endovascular era. Neurosurgery. 2014;74(5):482-497; discussion 497-488. Abla AA, McDougall CM, Breshears JD, Lawton MT. Intracranial-to-intracranial bypass for posterior inferior cerebellar artery aneurysms: options, technical challenges, and results in 35 patients. J Neurosurg. 2016;124(5):1275-1286. Liew D, Ng PY, Ng I. Surgical management of ruptured and unruptured symptomatic posterior inferior cerebellar artery aneurysms. Br J Neurosurg. 2004;18(6):608-612. Mukonoweshuro W, Laitt RD, Hughes DG. Endovascular treatment of PICA aneurysms. Neuroradiology. 2003;45(3):188-192. Natarajan SK, Lin N, Sonig A, et al. The safety of Pipeline flow diversion in fusiform vertebrobasilar aneurysms: a consecutive case series with longer-term follow-up from a single US center. J Neurosurg. 2016;125(1):111-119. Kan P, Srinivasan VM, Mbabuike N, et al. Aneurysms with persistent patency after treatment with the Pipeline Embolization Device. J Neurosurg. 2016:1-5.
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Lister JR, Rhoton AL, Jr., Matsushima T, Peace DA. Microsurgical anatomy of the posterior inferior cerebellar artery. Neurosurgery. 1982;10(2):170-199. Sejkorova A, Petr O, Mulino M, et al. Management of posterior inferior cerebellar artery aneurysms: What factors play the most important role in outcome? Acta Neurochir (Wien). 2017;159(3):549-558. Cho KC, Kim YB, Suh SH, Joo JY, Hong CK. Multidisciplinary management for the treatment of proximal posterior inferior cerebellar artery aneurysms. Neurological research. 2017;39(5):403-413.
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Figure 1: PICA Anatomy and Aneurysms: The PICA anatomy is demonstrated including the
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VA-PICA junction followed by the 5 segments: anterior medullary (AM), lateral medullary
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(LM), tonsillomedullary (TM), telovelotonsillar (TVT), and cortical branches (CB). Figure by
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Jill Gregory. Printed with permission of ©Mount Sinai Health System.
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Figure 2: VA – PICA Junction: A patient with subarachnoid hemorrhage who was found to
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have both a basilar tip aneurysm and a saccular aneurysm arising at the origin of the PICA from
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the right vertebral artery (a). The vertebral artery (v), basilar artery (b), PICA (p), and aneurysm
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(arrow) are labeled. The aneurysm neck was incorporated into the origin of PICA. Therefore the
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aneurysm was treated with balloon assisted coiling (b). The balloon microcatheter and microwire
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(arrowhead) can be seen supporting the PICA and the coil mass within the aneurysm (arrow). A
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delayed angiogram demonstrated complete aneurysm occlusion (c).
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Figure 3: Anterior Medullary Segment: A patient with a ruptured fusiform aneurysm (arrow)
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of the anterior medullary segment of the right PICA (a). Given the fusiform nature of the
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aneurysm and proximity to the brainstem perforators, the decision was made to proceed with
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microsurgical clipping via a right far lateral suboccipital craniectomy and C1 laminectomy. The
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aneurysm (arrow) can be seen distal to the vertebral artery (v), arising from the proximal PICA
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(p), inferior to the cerebellum (c), and lateral to the brainstem (bs). The aneurysm was secured
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with a bayonetted clip (b). The postoperative angiogram demonstrated complete aneurysm
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occlusion with no evidence of PICA stenosis (c).
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Figure 4: Lateral Medullary Segment: A patient with a ruptured dissecting aneurysm (arrow)
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of the lateral medullary segment of the right PICA (a). In this case the aneurysm arose distal to
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the brainstem perforators, so the patient was treated with parent vessel occlusion using coils (b).
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extracranial, saccular PICA aneurysm (arrow) that was treated with coiling (a). The patient
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presented again 1 month later with symptoms from a Chiari I malformation and tonsillar ectopia
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and marked hydromyelia that appeared to be exacerbated by the coil mass (arrow; b). The patient
541
was re-treated with a suboccipital craniectomy, C1-2 laminectomy, aneurysm trapping and
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excision (e-f), end-to-end PICA anastomosis, and expansile duraplasty (c-d). The coiled
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aneurysm (arrow) can be seen arising from the caudal loop of PICA (p) indenting the posterior
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cervical spinal cord (sc), inferior to the cerebellar tonsils (t). Post-operative angiogram
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demonstrated no evidence of residual aneurysm, a patent bypass, and shortening of the
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previously-elongated PICA (e). An MRI performed four months after surgery demonstrated
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interval elevation of the cerebellar tonsils above the foramen magnum and marked involution of
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the hydromyelia (f). Content similar to previously published material (Neurosurgery. 2015
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Oct;77(4):E660-5). Printed with permission from Wolters Kluwer Health, Inc (License number
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3998320582001).
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Figure 6: Telovelotonsillar Segment: A patient with a small vermian hematoma who was found
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to have a right cerebellar (tentorial) AVM (arrowhead) with a fusiform in-flow aneurysm (arrow)
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arising from the telovelotonsillar (TVT) segment of PICA (a). The aneurysm was the source of
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hemorrhage and was treated with coil occlusion of the superior division of the PICA without
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evidence of cerebellar infarction. Two weeks later the patient was taken to the operating room
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for resection of the AVM (b). The venous trunk (thick arrow) seen to enter the transverse sinus
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(t) contains a mix of flow from the arterialized vein medially (arrow) and the normal vein
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laterally (arrowhead). The cerebellar surface (c) appeared relatively normal with the AVM deep
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to it. A final angiogram demonstrated no residual aneurysm or AVM (c).
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initial angiogram did not demonstrate a vascular lesion. Repeat angiogram 1 week after
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presentation demonstrated a distal, cortical PICA aneurysm (arrow; a). Given its distal location,
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the aneurysm was treated with parent vessel occlusion (PVO) using a combination of nBCA and
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coilsaarow; b resulting in complete aneurysm occlusion (c). The patient did not have an MRI but
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there was no infarction on CT scan.
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Figure 8: Multimodality Treatment of PICA Aneurysms: A comprehensive approach should
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be taken for PICA aneurysms, including an assortment of endovascular and microsurgical
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treatments and re-treatments. Figure by Jill Gregory. Printed with permission of ©Mount Sinai
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Health System.
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Figure 10: Treatment Algorithm
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Table 1: Clinical Information
Hunt Hess Grade 1 2 3 4 5
3 4 11 2 5
12.0 16.0 44.0 8.0 20.0
SAH-Associated Cerebellar ICH
6
24.0
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83.3 13.3 3.3
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CLINICAL PRESENTATION SAH 25 Incidental Finding 4 Family History of Aneurysms 1
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Table 1. CLINICAL INFORMATION Category No. % DEMOGRAPHICS Patients 30 Aneurysms 30 Female 23 76.7 Male 7 23.3 Age Range 17-87 years Average Age 55.9 Years
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SAH, subarachnoid hemorrhage; ICH, intracerebral hemorrhage
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Table 2: Aneurysm Information
VA-PICA Junction Anterior Medullary Lateral Medullary Tonsillomedullary Telovelotonsillar Cortical Branch
8 7 3 1 5 6
26.7 23.3 10.0 3.3 16.7 20.0
ANEURYSM TYPE 15 14 1
50.0 46.7 3.3
Saccular Fusiform Dissecting
7
23.3
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Table 2. ANEURYSM SITE & NATURE Category No. % VESSEL & ANEURYSM ORIGIN PICA ORIGIN Intradural 28 93.3 Extradural 2 6.7
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ANEURYSM DIMENSIONS Max Diameter 4.91 mm Average. Diameter 4.08 mm Neck 2.59 mm 3 Volume 55.7 mm Aspect Ratio 2.27
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VA-PICA, vertebral artery – posterior inferior cerebellar artery
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Table 3: Treatment Information Table 3. TREATMENT INFORMATION Category No. INITIAL TREATMENT ELECTED Surgical Clip Reconstruction 6 Parent Vessel Occlusion 2 Endovascular Stand Alone Coiling 13 Balloon Assisted Coiling 1 Stent Assisted Coiling 1 Flow Diversion 1 Parent Vessel Occlusion 6
43.3 3.3 3.3 3.3 20.0
SUPPLEMENTAL TREATMENT Suboccipital Craniectomy after EVT 1 AVM resection 5
4.5 71.4
2
10.0 3.3 3.3 3.3
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60.0 30.0 10.0
RECURRENCE & RETREATMENT Recurrence 7 Retreatment 6 Clip Reconstruction 4 Bypass (End-To-End) 1 Stand Alone Coiling 1
23.3 20.0 66.7 16.7 16.7
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INITIAL OCCLUSION CLASSIFICATION Complete Occlusion 18 Neck Remnant 8 Residual Aneurysm 3
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COMPLICATIONS OF TREATMENT Procedural Complications 3 Extravasation 1 Vessel Compromise 1 Coil Prolapse 1
%
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Table 4: Clinical Information Table 4. Clinical Outcomes Category No. DISCHARGE mRS Good (0 – 2) 13 Poor (3 – 6) 17
43.3 56.7
FOLLOW-UP mRS Good (0 – 2) 22 Poor (3 – 6) 4
84.6 15.4
Death
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Table 5: Associations with Outcome Table 5
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Clinical Outcome Good Poor P Value (n=22) (n=4) 53.2 62.3 0.118 0.0896 19 (86.4) 2 (50.0) 3 (13.6) 2 (50.0) 17 (77.3) 4 (100) 0.008 15 (88.2) 1 (25.0) 2 (11.8) 3 (75.0) 0.991 6 (27.3) 1 (25.0) 6 (27.3) 1 (25.0) 1 (4.6) 0 (0.0) 1 (4.6) 0 (0.0) 4 (18.2) 1 (25.0) 4 (18.2) 1 (25.0) 0.867 12 (54.6) 2 (50.0) 10 (45.5) 2 (50.0) 11 (50.0) 1 (25.0) 0.356
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Angiographic Outcome Non-Recurrent Recurrent P Value (n=23) (n=7) Age 57.6 50.4 0.054 Gender 0.708 Female 18 (78.3) 5 (71.4) Male 5 (21.7) 2 (28.6) SAH 19 (82.6) 6 (85.7) 0.847 Hunt Hess 0.739 Good (I – III) 14 (73.7) 4 (57.1) Poor (IV – V) 5 (26.3) 2 (28.6) Location 0.050 VPJ 7 (30.4) 1 (14.3) AM 3 (13.0) 4 (57.1) 0.016* LM 3 (13.0) 0 (0.0) TM 0 (0.0) 1 (14.3) TVT 4 (17.4) 1 (14.3) Cortical 6 (26.1) 0 (0.0) Location 0.195 Proximal 10 (43.5) 5 (71.4 Distal 13 (56.5) 2 (28.6) Saccular 11 (47.8) 4 (57.4) 0.666 Treatment 0.896 Surgical 6 (26.1) 2 (28.5) EVT 17 (73.9) 5 (71.4) *AM compared to all other locations
6 (27.3) 16 (72.7)
2 (50.0) 2 (50.0)
0.365
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SAH = subarachnoid hemorrhage; VPJ = vertebral PICA junction; AM = anterior medullary; LM = lateral medullary; TM = tonsillomedullary; TVT = telovelotonsillar; EVT = endovascular treatment
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Highlights: •
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Our five-year modern experience highlights the diversity of PICA aneurysms and the need for multimodality paradigms to treat them successfully. The AM segment has the highest recurrence rate. Aggressive management is warranted given that the majority of patients can have a good neurological outcome.
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PICA – posterior inferior cerebellar artery SAH – subarachnoid hemorrhage VA – vertebral artery AM – anterior medullary PVO – parent vessel occlusion AVM – arteriovenous malformation VPJ – vertebral artery PICA junction EMR – electronic medical record DSA – digital subtraction angiography LM – lateral medullary TM – tonsillomedullary TVT – telovelotonsillar CB – cortical branches mRS – modified Rankin Scale CMF – cerebellomedullary fissure FD – flow diversion BAC – balloon-assisted coiling SAC – stent-assisted coiling
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Abbreviations: