- Email: [email protected]
Evaluation of a Traumatic Vertebral Artery Occlusion
Accepted Manuscript Evaluation of a traumatic vertebral artery occlusion Jaclyn J. Renfrow, Mark B. Frenkel, Matthew S. Edwards, John A. Wilson PII:
S1878-8750(17)30262-0
DOI:
10.1016/j.wneu.2017.02.089
Reference:
WNEU 5320
To appear in:
World Neurosurgery
Received Date: 16 November 2016 Revised Date:
17 February 2017
Accepted Date: 18 February 2017
Please cite this article as: Renfrow JJ, Frenkel MB, Edwards MS, Wilson JA, Evaluation of a traumatic vertebral artery occlusion, World Neurosurgery (2017), doi: 10.1016/j.wneu.2017.02.089. 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 Renfrow
Evaluation of a traumatic vertebral artery occlusion Jaclyn J. Renfrowa; Mark B. Frenkela; Matthew S. Edwardsb; John A. Wilsona Department of Neurosurgery, Wake Forest Baptist Health, Winston-Salem, North Carolina, 27157, USA
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a
b
E-mail addresses: Mark Frenkel, MD – [email protected] Matthew Edwards, MD – [email protected] John Wilson, MD – [email protected]
Jaclyn J. Renfrow, MD Medical Center Boulevard Winston-Salem, NC 27157-1082 Tel: 336-716-4020 Fax: 336-716-3065 E-mail: [email protected]
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Conflicts of Interest: None
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Corresponding author
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Department of Vascular and Endovascular Surgery, Wake Forest Baptist Health, Winston-Salem, North Carolina, 27157, USA
Keywords: Stroke, Trauma, Posterior Cerebral Circulation, Cerebrovascular Circulation, Revascularization
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Abbreviations: CTA (computed tomographic angiography) This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
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Abstract
Background Penetrating neck injury occurs in 5-10% of all trauma cases and carries a significant burden of morbidity and mortality (15%). We describe the evaluation and management of a 25 year-old man shot in the neck with occlusion of the left vertebral artery from its origin to C6. This is a case report where medical data was retrospectively analyzed with institutional IRB approval. Case Description Neurologic examination revealed paresthesias and dysesthesias in a left C8 dermatomal distribution. Computed tomography angiography of the neck demonstrated no opacification of the left vertebral artery from its origin to C6. MRI cervical spine revealed an acute infarct in the left cerebellum. A cerebral angiogram highlighted hemodynamic compromise and the patient was felt to be at significant risk of further cerebral infarction. Augmenting flow to the posterior circulation would mitigate that risk. The patient was taken to the operating room for a transposition of the vertebral artery to the common carotid artery.
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Conclusions The patient presented with silent cerebellar infarction due to a vertebral artery injury and impending vertebrobasilar insufficency. This case demonstrates clinical evaluation of the posterior circulation and treatment with a bypass technique through mobilization of the vertebral artery from the boney vertebral foramen with anastomosis to the common carotid.
Background and Importance Penetrating neck injury occurs in 5-10% of all trauma cases and
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carry a significant burden of morbidity and mortality (15%). We describe the evaluation and management of a case of a 25 year-old man shot in the neck with occlusion of the left vertebral artery from its origin to C6. The literature on vertebral artery injuries suggest they can usually be managed without surgery and anti-platelet therapy1, however, considering the physiologic blood
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flow given the patient’s anatomy on imaging studies suggested this patient was at high risk for vertebrobasilar insufficiency and cerebral infarction. This is a case report where data was
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retrospectively analyzed with institutional IRB approval from the medical record. Clinical Presentation The patient is a 25 year-old male with no significant past medical history sustained a gunshot wound to the left neck. He was taken by EMS to the emergency department where he was hemodynamically stable. He underwent evaluation by trauma surgery and was determined to have no airway injury, no esophageal injury. He complained of neck pain with paresthesias and dysesthesias to his left hand in a C8 dermatomal distribution. He underwent
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CTA (computed tomographic angiography) of the neck which demonstrated no opacification of the left vertebral artery from its origin to C6. The bullet was noted to be lodged in the anterior aspect of the T1 vertebral body along with a fracture of the inferior endplate of C7 (Figure 1).
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Our review of the CTA raised concern for adequacy of blood supply to the posterior circulation. The right vertebral artery ends in PICA and the posterior communicating arteries are quite small
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contributing very little to flow in the posterior circulation. This underscored that the left vertebral artery was the dominant contributor to the basilar artery and the primary source of blood supply to the posterior circulation. The patient was admitted to the intensive care unit and started on Aspirin 325mg. He underwent a MRI cervical spine which ruled out injury to the spinal cord but did highlight edema in the C7 and C8 nerve roots. An additional acute infarct was visualized in the left cerebellum. In order to get a more complete picture of the anatomy and blood flow, we obtained a diagnostic cerebral angiogram (Figure 2). The angiogram confirmed the anatomic findings of the CTA. It also demonstrated delayed filling of the basilar artery primarily through muscular collaterals arising 2
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from left subclavian branches. This degree of hemodynamic compromise was felt to place the patient at significant risk of further cerebral infarction. We felt augmenting flow to the posterior circulation with some form of bypass would mitigate that risk.
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Neurosurgery and vascular surgery collaborated and believed the best option would be a transposition of the vertebral to carotid after mobilization of the vertebral artery out of the
vertebral foramen in the mid-cervical region above the level of injury and occlusion. A key component in planning and executing this atypical reconstruction was the consideration of
SC
creating an optimal geometry to re-establish flow. Given the size of the vessel we felt that
reimplantation would be optimal in comparison to a bypass. In looking at the natural orientation of the vessel and with the desire to establish a gentle angle for the entry back into the vertebral
M AN U
foramen, we felt that a low, posterior reimplant onto the carotid was optimal. Given the size and need for an end-to-side anastomosis, we opted for creating a ‘punch out’ defect in the posterior wall to reduce the propensity for the reimplanted vertebral to narrow or collapse. After obtaining informed consent the patient was taken to the operating room for a transposition of the vertebral artery to the common carotid artery (Figure 3). A linear incision was made
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along the anterior border of the sternocleidomastoid muscle. After dividing the platysma, dissection along the anterior border of the sternocleidomastoid proceeded down to the carotid sheath. The carotid was mobilized circumferentially. Dissection then proceeded to the longus colli muscle and out to the transverse processes. The C5 transverse process was identified with a
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fluoroscopic image. The C4, C5 and C6 transverse processes were exposed along with the vertebral. A Kerrison rongeur was used to completely unroof the vertebral foramen and mobilize
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the vertebral artery circumferentially. We identified the exiting cervical nerve roots protecting those. The vertebral artery was transected just below the C6 vertebral foramen after placing a titanium hemoclip on the proximal end. There was good back bleeding through the artery and it was secured with a small temporary aneurysm clip. We then mobilized the artery towards the posterior wall of the common carotid. The carotid was controlled proximally and distally. The geometry of the vessels was such that the best location for implantation of the vertebral was the posterior wall of the common carotid. Traction ligatures were placed through two portions of the adventitia to help us rotate the carotid so we could see the posterior wall. A small arteriotomy was created in the posterior surface at the appropriate location with an 11 blade and then a 3-mm 3
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coronary punch. A direct transposition of the vertebral to common carotid with a running suture of 6-0 Prolene was performed. When this was complete, the entire area was back flushed to evacuate air using the quite robust back flow through the vertebral artery. The vessels were returned to their anatomic location and were inspected to assure the reconstructed vertebral was
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without kinking or tension. Control was then released from the distal carotid. A flow probe was used to assess adequacy of flow and demonstrated 100mL per minute to the left vertebral artery. Post-operatively the patient awoke in good condition. Upon neurologic examination, the patient
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was noted to have a left Horner’s syndrome which was attributed to dissection of the sympathetic chain overlying the longus coli muscles during exposure of the foramen transversarium. He also had very mild weakness of the left bicep which was attributed to neuropraxia of the left C5 nerve
continued on Aspirin 650mg daily.
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root. Patency of the new construct was subsequently confirmed by CTA (Figure 4). He was
The patient was discharged to home on post-op day three. He continued to improve and by his outpatient clinic follow up had a minimal residual left Horner’s syndrome and was full and symmetric in his strength.
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Discussion Penetrating injury to the neck has an incidence of 5-10% of all trauma cases presenting to the emergency department 2. These injuries carry a significant burden of morbidity and mortality (15%) given the density of vital structures passing through this region 3. The initial evaluation centers on the airway, breathing, and circulation. In patients without life-
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threatening injuries the most commonly used imaging is CTA which outlines the path of penetrating injury and identifies occult injuries to vital structures4. Management of zone II
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(spanning from the cricoid cartilage to the angle of the mandible) injuries without evidence of significant underlying trauma (such as shock, pulsatile/expending hematoma, subcutaneous emphysema, stridor, hematemesis, lateralizing neurologic deficit) is debated in the literature as to whether observation or surgical neck exploration are the most appropriate course of action. Arterial injuries occur in about 12% of penetrating neck trauma and are managed surgical by first obtaining proximal and distal control. Isolated injuries may be repaired primarily. More extensive injuries may require segmental resection with direct anastomosis or graft implantation, bypass, or sacrifice. 4
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Vertebral artery injury is very uncommon in penetrating neck trauma due to its location within the bony confines of the vertebral column 4. Anatomically the vertebral artery is divided into four segments from the proximal (V1) which spans from its origin to the entry into the foramen transversarium, V2 ranges along the entire cephalad course in the foramen transversarium, V3
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starts where the artery emerges along C2 to the more lateral C1 foramen transversarium, V3 beginning after exit of the C1 transversarium along the superior portion of the C1 posterior arch, and V4 after piercing the dura to become intracranial5,6. The most commonly cited level of
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injury occurs at V2 where tethering to the foramen transversarium occurs7.
The confluence of bilateral vertebral arteries into the basilar artery is the anatomic basis by which unilateral vertebral artery occlusion often remains asymptomatic. The circle of Willis
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allows contribution from the anterior circulation to the posterior circulation affording further protection against hemodynamic compromise. Asymmetry of the vertebral arteries is present in 40 percent of patients with left vertebral artery dominance in 60% of patients. In approximately 15% of patients there is marked asymmetry with a hypoplastic vertebral artery, the right 10% of cases and the left 5%. Atretic vertebral artery anatomic variants without contribution to the patients 3.
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basilar and termination in PICA occurs on the left in 3% of patients and on the right in 2% of
Initially asymptomatic patients can have progression of symptoms either acutely or in a delayed fashion due to embolism, thrombus extension, or dissection 7. The interval from spinal injury to later8.
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development of vertebrobasilar ischemic symptoms has been reported as long as three months
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Treatment of symptomatically occluded vertebral arteries varies9. The American Association of Neurological Surgeons/Congress of Neurological Surgeons Guidelines consensus concluded that patients with a posterior circulation stroke and a vertebral artery injury in nonpenetrating trauma have a better outcome when treated with intravenous heparin than patients who do not receive this treatment 1. However, complications associated with anticoagulation in the trauma population can be significant. A study by Eachempati et al. revealed only 14% of trauma patients are candidates for full anticoagulation, supporting the movement to treatment with antiplatelet agents instead for a period of three months 10. There are no clinical trials supporting this as definitive therapy to date. Injuries warranting intervention include acute hemorrhage, 5
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pseudoaneurysm due to risk of rupture and an embolic source, and arteriovenous fistula formation. Indications for bypass surgery in the posterior circulation are more ambiguous than those in the
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anterior circulation. Cerebral revascularization in the posterior circulation is well recognized as an important component in the treatment of complex and giant intracranial aneurysms and
tumors11. A role in cases of atherosclerotic vertebrobasilar insufficiency remains to be proven though similar operative techniques using a direct vertebral to carotid transposition have been
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utilized for this indication12. Additionally, there are reports of application for the proximal vertebral to common carotid transposition in the literature as a treatment for symptomatic
subclavian steal syndrome 13. In this case the patient presented with silent cerebellar infarction.
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It is possible the infarct was embolic in nature. But there was angiographic evidence indicating significant cerebrovascular compromise of the vertebrobasilar circulation. The assessment of the treating team was that the patient was at significant risk of hemodynamic insufficiency to further infarct. Flow augmentation with some form of bypass was felt to be the best way to minimize that risk. This case demonstrates a bypass technique with mobilization of the vertebral artery distal to an injury from the boney vertebral foramen with anastomosis to the common carotid.
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Studies documenting blood flow in bypass procedures have established normal vertebral artery blood flow ranges from 45 to 90 mL per minute 14. Measurement of post-operative flow for this case was 100 mL per minute, which is within physiologic range.
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Conclusions Most vertebral artery injuries are asymptomatic because of collateral blood flow through the contralateral vertebral artery. Yet, an injured vertebral artery is a potential source for
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thrombus propagation, embolization, or hemodynamic compromise with resultant neurologic injury. A thorough understanding of the physiologic circulation to the downstream vital organs must be assessed with an acute arterial injury. In this particular case a normal anatomic variant (the right vertebral artery ending in PICA) underscored a critical contribution of the left vertebral artery to the posterior circulation. The management of this case hinged on recognizing these implications. A vertebral to common carotid artery bypass can restore physiologic range of anterograde blood flow into the posterior circulation.
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References 1.
Management of vertebral artery injuries after nonpenetrating cervical trauma. Neurosurgery. 2002;50(3
2.
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Suppl):S173-8. http://www.ncbi.nlm.nih.gov/pubmed/12431302. Accessed June 2, 2016. Shankar PV. Penetrating Neck Trauma. In: Critical Findings in Neuroradiology. Cham: Springer International Publishing; 2016:349-353. doi:10.1007/978-3-319-27987-9_41.
Greenberg M. Handbook of Neurosurgery. 8th ed. New York: Thieme ; 2016.
4.
Cameron J, Cameron A. Current Surgical Therapy. 10th ed. Atlanta : Elsevier Health Sciences ; 2011.
5.
Akgun V, Battal B, Bozkurt Y, et al. Normal anatomical features and variations of the vertebrobasilar
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circulation and its branches: an analysis with 64-detector row CT and 3T MR angiographies. ScientificWorldJournal. 2013;2013:620162. doi:10.1155/2013/620162. 6.
George B, Cornelius J. Vertebral artery: Surgical anatomy. Oper Tech Neurosurg. 2001;4(4):168-181. doi:10.1053/otns.2001.30168.
Herkowitz H, Garfin S, Eismont F, Bell G, Balderston R. Rothman-Simeone The Spine. 6th ed. Philadelphia : Saunders ; 2011.
8.
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7.
Inamasu J, Guiot BH. Vertebral artery injury after blunt cervical trauma: an update. Surg Neurol.
Golueke P, Sclafani S, Phillips T, Goldstein A, Scalea T, Duncan A. Vertebral artery injury--diagnosis and
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9.
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2006;65(3):238-45-6. doi:10.1016/j.surneu.2005.06.043.
management. J Trauma. 1987;27(8):856-865. http://www.ncbi.nlm.nih.gov/pubmed/3612862. Accessed
June 2, 2016.
10.
Eachempati SR, Vaslef SN, Sebastian MW, Reed RL. Blunt vascular injuries of the head and neck: is heparinization necessary? J Trauma. 1998;45(6):997-1004. http://www.ncbi.nlm.nih.gov/pubmed/9867039. Accessed June 2, 2016.
11.
Kawashima M, Rhoton AL, Tanriover N, Ulm AJ, Yasuda A, Fujii K. Microsurgical anatomy of cerebral
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revascularization. Part II: posterior circulation. J Neurosurg. 2005;102(1):132-147. doi:10.3171/jns.2005.102.1.0132. 12.
Rangel-Castilla L, Kalani MYS, Cronk K, Zabramski JM, Russin JJ, Spetzler RF. Vertebral artery
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transposition for revascularization of the posterior circulation: a critical assessment of temporary and
permanent complications and outcomes. J Neurosurg. 2015;122(3):671-677. doi:10.3171/2014.9.JNS14194. 13.
Bohmfalk GL, Story JL, Brown WE, Marlin AE. Subclavian steal syndrome. Part 1: Proximal vertebral to
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common carotid artery transposition in three patients, and historical review. J Neurosurg. 1979;51(5):628640. doi:10.3171/jns.1979.51.5.0628.
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Bohmfalk GL, Story JL, Brown WE, Marlin AE. Subclavian steal syndrome. Part 2: Intraoperative vertebral
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artery blood flow measurement. J Neurosurg. 1979;51(5):641-643. doi:10.3171/jns.1979.51.5.0641.
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14.
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Figure Legends Figure 1. Sagittal CT of the cervical spine demonstrating the bullet lodged into the anterior aspect of the T1
spanning from its origin to the C6 level with distal reconstitution.
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vertebral body. Coronal CTA demonstrating lack of opacification in the left vertebral artery from a segment
Figure 2. Left Vertebral artery V1 segment stump seen. Artery reconstitutes at C6 via collaterals through left
subclavian and left occipital artery. At C6 level, where the artery reforms, there is presence of the meniscus,
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indicating thrombus. Some reconstitution and reverse flow through the right vertebral artery injection also seen. Right vertebral artery ends in a PICA. Small bilateral posterior communicating arteries visualized on bilateral
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internal cerebral artery injections.
Figure 3. Intra-operative photographs demonstrating the mobilized left vertebral artery adjacent to the common carotid artery with a visualized punch out site as the proposed site of an end-to-side anastomosis. Final picture of the anastomosis after back-bleeding and final closure with its final configuration without tension or torque on the vertebral artery.
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Figure 4. A) Serial sagittal images of the left carotid artery from the post-operative CTA of the neck demonstrating the final transposition of the vertebral to common carotid construct with the site widely patent. B) Reconstructed
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images of the transposition.
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Highlights
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Most vertebral artery injuries are asymptomatic because of collateral blood flow. Physiologic circulation must be assessed with an arterial injury. In this case a normal anatomic variant (the right vertebral artery ending in PICA) was insufficient with a left vertebral injury. Arterial injury risks include thrombosis, embolization, or hemodynamic compromise. A vertebral bypass can restore physiologic range of blood flow.
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• • •
S1878-8750(17)30262-0
DOI:
10.1016/j.wneu.2017.02.089
Reference:
WNEU 5320
To appear in:
World Neurosurgery
Received Date: 16 November 2016 Revised Date:
17 February 2017
Accepted Date: 18 February 2017
Please cite this article as: Renfrow JJ, Frenkel MB, Edwards MS, Wilson JA, Evaluation of a traumatic vertebral artery occlusion, World Neurosurgery (2017), doi: 10.1016/j.wneu.2017.02.089. 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 Renfrow
Evaluation of a traumatic vertebral artery occlusion Jaclyn J. Renfrowa; Mark B. Frenkela; Matthew S. Edwardsb; John A. Wilsona Department of Neurosurgery, Wake Forest Baptist Health, Winston-Salem, North Carolina, 27157, USA
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a
b
E-mail addresses: Mark Frenkel, MD – [email protected] Matthew Edwards, MD – [email protected] John Wilson, MD – [email protected]
Jaclyn J. Renfrow, MD Medical Center Boulevard Winston-Salem, NC 27157-1082 Tel: 336-716-4020 Fax: 336-716-3065 E-mail: [email protected]
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Conflicts of Interest: None
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Corresponding author
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Department of Vascular and Endovascular Surgery, Wake Forest Baptist Health, Winston-Salem, North Carolina, 27157, USA
Keywords: Stroke, Trauma, Posterior Cerebral Circulation, Cerebrovascular Circulation, Revascularization
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Abbreviations: CTA (computed tomographic angiography) This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
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Abstract
Background Penetrating neck injury occurs in 5-10% of all trauma cases and carries a significant burden of morbidity and mortality (15%). We describe the evaluation and management of a 25 year-old man shot in the neck with occlusion of the left vertebral artery from its origin to C6. This is a case report where medical data was retrospectively analyzed with institutional IRB approval. Case Description Neurologic examination revealed paresthesias and dysesthesias in a left C8 dermatomal distribution. Computed tomography angiography of the neck demonstrated no opacification of the left vertebral artery from its origin to C6. MRI cervical spine revealed an acute infarct in the left cerebellum. A cerebral angiogram highlighted hemodynamic compromise and the patient was felt to be at significant risk of further cerebral infarction. Augmenting flow to the posterior circulation would mitigate that risk. The patient was taken to the operating room for a transposition of the vertebral artery to the common carotid artery.
1
ACCEPTED MANUSCRIPT Renfrow
Conclusions The patient presented with silent cerebellar infarction due to a vertebral artery injury and impending vertebrobasilar insufficency. This case demonstrates clinical evaluation of the posterior circulation and treatment with a bypass technique through mobilization of the vertebral artery from the boney vertebral foramen with anastomosis to the common carotid.
Background and Importance Penetrating neck injury occurs in 5-10% of all trauma cases and
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carry a significant burden of morbidity and mortality (15%). We describe the evaluation and management of a case of a 25 year-old man shot in the neck with occlusion of the left vertebral artery from its origin to C6. The literature on vertebral artery injuries suggest they can usually be managed without surgery and anti-platelet therapy1, however, considering the physiologic blood
SC
flow given the patient’s anatomy on imaging studies suggested this patient was at high risk for vertebrobasilar insufficiency and cerebral infarction. This is a case report where data was
M AN U
retrospectively analyzed with institutional IRB approval from the medical record. Clinical Presentation The patient is a 25 year-old male with no significant past medical history sustained a gunshot wound to the left neck. He was taken by EMS to the emergency department where he was hemodynamically stable. He underwent evaluation by trauma surgery and was determined to have no airway injury, no esophageal injury. He complained of neck pain with paresthesias and dysesthesias to his left hand in a C8 dermatomal distribution. He underwent
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CTA (computed tomographic angiography) of the neck which demonstrated no opacification of the left vertebral artery from its origin to C6. The bullet was noted to be lodged in the anterior aspect of the T1 vertebral body along with a fracture of the inferior endplate of C7 (Figure 1).
EP
Our review of the CTA raised concern for adequacy of blood supply to the posterior circulation. The right vertebral artery ends in PICA and the posterior communicating arteries are quite small
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contributing very little to flow in the posterior circulation. This underscored that the left vertebral artery was the dominant contributor to the basilar artery and the primary source of blood supply to the posterior circulation. The patient was admitted to the intensive care unit and started on Aspirin 325mg. He underwent a MRI cervical spine which ruled out injury to the spinal cord but did highlight edema in the C7 and C8 nerve roots. An additional acute infarct was visualized in the left cerebellum. In order to get a more complete picture of the anatomy and blood flow, we obtained a diagnostic cerebral angiogram (Figure 2). The angiogram confirmed the anatomic findings of the CTA. It also demonstrated delayed filling of the basilar artery primarily through muscular collaterals arising 2
ACCEPTED MANUSCRIPT Renfrow
from left subclavian branches. This degree of hemodynamic compromise was felt to place the patient at significant risk of further cerebral infarction. We felt augmenting flow to the posterior circulation with some form of bypass would mitigate that risk.
RI PT
Neurosurgery and vascular surgery collaborated and believed the best option would be a transposition of the vertebral to carotid after mobilization of the vertebral artery out of the
vertebral foramen in the mid-cervical region above the level of injury and occlusion. A key component in planning and executing this atypical reconstruction was the consideration of
SC
creating an optimal geometry to re-establish flow. Given the size of the vessel we felt that
reimplantation would be optimal in comparison to a bypass. In looking at the natural orientation of the vessel and with the desire to establish a gentle angle for the entry back into the vertebral
M AN U
foramen, we felt that a low, posterior reimplant onto the carotid was optimal. Given the size and need for an end-to-side anastomosis, we opted for creating a ‘punch out’ defect in the posterior wall to reduce the propensity for the reimplanted vertebral to narrow or collapse. After obtaining informed consent the patient was taken to the operating room for a transposition of the vertebral artery to the common carotid artery (Figure 3). A linear incision was made
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along the anterior border of the sternocleidomastoid muscle. After dividing the platysma, dissection along the anterior border of the sternocleidomastoid proceeded down to the carotid sheath. The carotid was mobilized circumferentially. Dissection then proceeded to the longus colli muscle and out to the transverse processes. The C5 transverse process was identified with a
EP
fluoroscopic image. The C4, C5 and C6 transverse processes were exposed along with the vertebral. A Kerrison rongeur was used to completely unroof the vertebral foramen and mobilize
AC C
the vertebral artery circumferentially. We identified the exiting cervical nerve roots protecting those. The vertebral artery was transected just below the C6 vertebral foramen after placing a titanium hemoclip on the proximal end. There was good back bleeding through the artery and it was secured with a small temporary aneurysm clip. We then mobilized the artery towards the posterior wall of the common carotid. The carotid was controlled proximally and distally. The geometry of the vessels was such that the best location for implantation of the vertebral was the posterior wall of the common carotid. Traction ligatures were placed through two portions of the adventitia to help us rotate the carotid so we could see the posterior wall. A small arteriotomy was created in the posterior surface at the appropriate location with an 11 blade and then a 3-mm 3
ACCEPTED MANUSCRIPT Renfrow
coronary punch. A direct transposition of the vertebral to common carotid with a running suture of 6-0 Prolene was performed. When this was complete, the entire area was back flushed to evacuate air using the quite robust back flow through the vertebral artery. The vessels were returned to their anatomic location and were inspected to assure the reconstructed vertebral was
RI PT
without kinking or tension. Control was then released from the distal carotid. A flow probe was used to assess adequacy of flow and demonstrated 100mL per minute to the left vertebral artery. Post-operatively the patient awoke in good condition. Upon neurologic examination, the patient
SC
was noted to have a left Horner’s syndrome which was attributed to dissection of the sympathetic chain overlying the longus coli muscles during exposure of the foramen transversarium. He also had very mild weakness of the left bicep which was attributed to neuropraxia of the left C5 nerve
continued on Aspirin 650mg daily.
M AN U
root. Patency of the new construct was subsequently confirmed by CTA (Figure 4). He was
The patient was discharged to home on post-op day three. He continued to improve and by his outpatient clinic follow up had a minimal residual left Horner’s syndrome and was full and symmetric in his strength.
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Discussion Penetrating injury to the neck has an incidence of 5-10% of all trauma cases presenting to the emergency department 2. These injuries carry a significant burden of morbidity and mortality (15%) given the density of vital structures passing through this region 3. The initial evaluation centers on the airway, breathing, and circulation. In patients without life-
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threatening injuries the most commonly used imaging is CTA which outlines the path of penetrating injury and identifies occult injuries to vital structures4. Management of zone II
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(spanning from the cricoid cartilage to the angle of the mandible) injuries without evidence of significant underlying trauma (such as shock, pulsatile/expending hematoma, subcutaneous emphysema, stridor, hematemesis, lateralizing neurologic deficit) is debated in the literature as to whether observation or surgical neck exploration are the most appropriate course of action. Arterial injuries occur in about 12% of penetrating neck trauma and are managed surgical by first obtaining proximal and distal control. Isolated injuries may be repaired primarily. More extensive injuries may require segmental resection with direct anastomosis or graft implantation, bypass, or sacrifice. 4
ACCEPTED MANUSCRIPT Renfrow
Vertebral artery injury is very uncommon in penetrating neck trauma due to its location within the bony confines of the vertebral column 4. Anatomically the vertebral artery is divided into four segments from the proximal (V1) which spans from its origin to the entry into the foramen transversarium, V2 ranges along the entire cephalad course in the foramen transversarium, V3
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starts where the artery emerges along C2 to the more lateral C1 foramen transversarium, V3 beginning after exit of the C1 transversarium along the superior portion of the C1 posterior arch, and V4 after piercing the dura to become intracranial5,6. The most commonly cited level of
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injury occurs at V2 where tethering to the foramen transversarium occurs7.
The confluence of bilateral vertebral arteries into the basilar artery is the anatomic basis by which unilateral vertebral artery occlusion often remains asymptomatic. The circle of Willis
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allows contribution from the anterior circulation to the posterior circulation affording further protection against hemodynamic compromise. Asymmetry of the vertebral arteries is present in 40 percent of patients with left vertebral artery dominance in 60% of patients. In approximately 15% of patients there is marked asymmetry with a hypoplastic vertebral artery, the right 10% of cases and the left 5%. Atretic vertebral artery anatomic variants without contribution to the patients 3.
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basilar and termination in PICA occurs on the left in 3% of patients and on the right in 2% of
Initially asymptomatic patients can have progression of symptoms either acutely or in a delayed fashion due to embolism, thrombus extension, or dissection 7. The interval from spinal injury to later8.
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development of vertebrobasilar ischemic symptoms has been reported as long as three months
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Treatment of symptomatically occluded vertebral arteries varies9. The American Association of Neurological Surgeons/Congress of Neurological Surgeons Guidelines consensus concluded that patients with a posterior circulation stroke and a vertebral artery injury in nonpenetrating trauma have a better outcome when treated with intravenous heparin than patients who do not receive this treatment 1. However, complications associated with anticoagulation in the trauma population can be significant. A study by Eachempati et al. revealed only 14% of trauma patients are candidates for full anticoagulation, supporting the movement to treatment with antiplatelet agents instead for a period of three months 10. There are no clinical trials supporting this as definitive therapy to date. Injuries warranting intervention include acute hemorrhage, 5
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pseudoaneurysm due to risk of rupture and an embolic source, and arteriovenous fistula formation. Indications for bypass surgery in the posterior circulation are more ambiguous than those in the
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anterior circulation. Cerebral revascularization in the posterior circulation is well recognized as an important component in the treatment of complex and giant intracranial aneurysms and
tumors11. A role in cases of atherosclerotic vertebrobasilar insufficiency remains to be proven though similar operative techniques using a direct vertebral to carotid transposition have been
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utilized for this indication12. Additionally, there are reports of application for the proximal vertebral to common carotid transposition in the literature as a treatment for symptomatic
subclavian steal syndrome 13. In this case the patient presented with silent cerebellar infarction.
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It is possible the infarct was embolic in nature. But there was angiographic evidence indicating significant cerebrovascular compromise of the vertebrobasilar circulation. The assessment of the treating team was that the patient was at significant risk of hemodynamic insufficiency to further infarct. Flow augmentation with some form of bypass was felt to be the best way to minimize that risk. This case demonstrates a bypass technique with mobilization of the vertebral artery distal to an injury from the boney vertebral foramen with anastomosis to the common carotid.
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Studies documenting blood flow in bypass procedures have established normal vertebral artery blood flow ranges from 45 to 90 mL per minute 14. Measurement of post-operative flow for this case was 100 mL per minute, which is within physiologic range.
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Conclusions Most vertebral artery injuries are asymptomatic because of collateral blood flow through the contralateral vertebral artery. Yet, an injured vertebral artery is a potential source for
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thrombus propagation, embolization, or hemodynamic compromise with resultant neurologic injury. A thorough understanding of the physiologic circulation to the downstream vital organs must be assessed with an acute arterial injury. In this particular case a normal anatomic variant (the right vertebral artery ending in PICA) underscored a critical contribution of the left vertebral artery to the posterior circulation. The management of this case hinged on recognizing these implications. A vertebral to common carotid artery bypass can restore physiologic range of anterograde blood flow into the posterior circulation.
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References 1.
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Greenberg M. Handbook of Neurosurgery. 8th ed. New York: Thieme ; 2016.
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circulation and its branches: an analysis with 64-detector row CT and 3T MR angiographies. ScientificWorldJournal. 2013;2013:620162. doi:10.1155/2013/620162. 6.
George B, Cornelius J. Vertebral artery: Surgical anatomy. Oper Tech Neurosurg. 2001;4(4):168-181. doi:10.1053/otns.2001.30168.
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June 2, 2016.
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Eachempati SR, Vaslef SN, Sebastian MW, Reed RL. Blunt vascular injuries of the head and neck: is heparinization necessary? J Trauma. 1998;45(6):997-1004. http://www.ncbi.nlm.nih.gov/pubmed/9867039. Accessed June 2, 2016.
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Kawashima M, Rhoton AL, Tanriover N, Ulm AJ, Yasuda A, Fujii K. Microsurgical anatomy of cerebral
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revascularization. Part II: posterior circulation. J Neurosurg. 2005;102(1):132-147. doi:10.3171/jns.2005.102.1.0132. 12.
Rangel-Castilla L, Kalani MYS, Cronk K, Zabramski JM, Russin JJ, Spetzler RF. Vertebral artery
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transposition for revascularization of the posterior circulation: a critical assessment of temporary and
permanent complications and outcomes. J Neurosurg. 2015;122(3):671-677. doi:10.3171/2014.9.JNS14194. 13.
Bohmfalk GL, Story JL, Brown WE, Marlin AE. Subclavian steal syndrome. Part 1: Proximal vertebral to
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common carotid artery transposition in three patients, and historical review. J Neurosurg. 1979;51(5):628640. doi:10.3171/jns.1979.51.5.0628.
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Bohmfalk GL, Story JL, Brown WE, Marlin AE. Subclavian steal syndrome. Part 2: Intraoperative vertebral
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artery blood flow measurement. J Neurosurg. 1979;51(5):641-643. doi:10.3171/jns.1979.51.5.0641.
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Figure Legends Figure 1. Sagittal CT of the cervical spine demonstrating the bullet lodged into the anterior aspect of the T1
spanning from its origin to the C6 level with distal reconstitution.
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vertebral body. Coronal CTA demonstrating lack of opacification in the left vertebral artery from a segment
Figure 2. Left Vertebral artery V1 segment stump seen. Artery reconstitutes at C6 via collaterals through left
subclavian and left occipital artery. At C6 level, where the artery reforms, there is presence of the meniscus,
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indicating thrombus. Some reconstitution and reverse flow through the right vertebral artery injection also seen. Right vertebral artery ends in a PICA. Small bilateral posterior communicating arteries visualized on bilateral
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internal cerebral artery injections.
Figure 3. Intra-operative photographs demonstrating the mobilized left vertebral artery adjacent to the common carotid artery with a visualized punch out site as the proposed site of an end-to-side anastomosis. Final picture of the anastomosis after back-bleeding and final closure with its final configuration without tension or torque on the vertebral artery.
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Figure 4. A) Serial sagittal images of the left carotid artery from the post-operative CTA of the neck demonstrating the final transposition of the vertebral to common carotid construct with the site widely patent. B) Reconstructed
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images of the transposition.
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Most vertebral artery injuries are asymptomatic because of collateral blood flow. Physiologic circulation must be assessed with an arterial injury. In this case a normal anatomic variant (the right vertebral artery ending in PICA) was insufficient with a left vertebral injury. Arterial injury risks include thrombosis, embolization, or hemodynamic compromise. A vertebral bypass can restore physiologic range of blood flow.
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