- Email: [email protected]
Seeing Floaters: A Case Report and Literature Review of Intraventricular Migration of Silicone Oil Tamponade Material for Retinal Detachment
Accepted Manuscript Seeing floaters – a case report and literature review of intraventricular migration of silicone oil tamponade material for retinal detachment Matthew B. Potts, Alex C. Wu, MD, David J. Rusinak, MD, Kartik Kesavabhotla, MD, Babak S. Jahromi, MD, PhD PII:
S1878-8750(18)30765-4
DOI:
10.1016/j.wneu.2018.04.049
Reference:
WNEU 7885
To appear in:
World Neurosurgery
Received Date: 18 February 2018 Revised Date:
8 April 2018
Accepted Date: 9 April 2018
Please cite this article as: Potts MB, Wu AC, Rusinak DJ, Kesavabhotla K, Jahromi BS, Seeing floaters – a case report and literature review of intraventricular migration of silicone oil tamponade material for retinal detachment, World Neurosurgery (2018), doi: 10.1016/j.wneu.2018.04.049. 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
Seeing floaters – a case report and literature review of intraventricular migration of
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silicone oil tamponade material for retinal detachment
Matthew B. Potts,1,2 Alex C. Wu, MD,2 David J. Rusinak, MD,2 Kartik Kesavabhotla, MD,1 Babak S. Jahromi, MD, PhD1,2
Departments of Neurological Surgery and 2Radiology
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1
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Northwestern Memorial Hospital
Northwestern University Feinberg School of Medicine
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Corresponding author:
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Chicago, IL 60611, USA.
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Matthew B. Potts, MD
676 N. St. Clair St., Suite 2210 Chicago, IL 60611
Email: [email protected] Phone: 312-695-6200 Fax: 312-695-0225
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ABSTRACT Background. Intraocular injection of silicone oil is commonly performed during vitrectomy to
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tamponade the retina in place for treatment of retinal detachment. Although rare, this intravitreal silicone can migrate through the optic nerve and chiasm and enter the cerebral ventricles.
Case description. Here we present a case report of a patient presenting with headache and
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intraventricular hyperdensities on computed tomography imaging raising concern for
intraventricular hemorrhage. The intraventricular hyperdensities, however, were in a non-
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dependent location and moved to a new non-dependent location when a repeat imaging was performed with the patient in a prone position. We provide a literature review of this phenomenon and discuss the relevant CT and MRI findings.
Conclusion. Intraocular silicone can rarely migrate into the cerebral ventricular system. Careful
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review of the clinical history and imaging findings can help distinguish this from other, more
BACKGROUND
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dangerous intracranial pathologies.
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Intravitreal injection of silicone oil is commonly performed during vitrectomy to tamponade the retina in place for treatment of retinal detachment.1 Such oils are viscous and hydrophobic silicone polymers or monomers and have been used for this purpose since the 1960s.2 A rare phenomenon associated with this treatment is migration of the silicone oil into the optic nerve and chiasm3-6 and even into the cerebral ventricular system.7-21 The mechanism of this migration is not well understood and intraventricular silicone oil can be confused for other intracranial pathologies such as intraventricular hemorrhage, tumor, or colloid cyst.18-20
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Awareness of this phenomenon is therefore important for neurosurgeons to avoid unnecessary workup or interventions.
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Here we present a case of intraventricular migration of silicone tamponade material that was initially diagnosed as intraventricular hemorrhage. We also review the literature, describe
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the imaging findings and techniques, and discuss the possible mechanisms of this phenomenon.
CASE
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A 56 year-old woman with multiple medical comorbidities, including insulin-dependent diabetes, was transferred to our institution with acute onset headache and face parasthesias and a report of intraventricular hemorrhage on non-contrast head computed tomography (CT). She was also hypertensive and hypoglycemic on presentation. A CT angiogram (CTA) upon arrival
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found no vascular abnormalities but again demonstrated non-dependent globular hyperdense foci within the frontal horns of both lateral ventricles (Figure 1A) as well as hyperdensity within the vitrea of the left eye and along the course of the left optic nerve and chiasm (Figure 1B and C,
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respectively). Magnetic resonance imaging (MRI) of the brain revealed the non-dependent intraventricular masses to be non-enhancing and hyperintense on T1 and T2/fluid attenuated
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inversion recovery (T2/FLAIR) imaging (Figure 2A). These masses also demonstrated peripheral gradient susceptibility (Figure 2B). In addition, there was hyperintense T2/FLAIR signal within the left vitreous chamber as well as abnormal hyperintense T2/FLAIR signal abnormality, intrinsic T1 shortening, and susceptibility along the left optic nerve that extended into the left aspect of the optic chiasm (Figure 3).
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Further review of the patient’s past medical history revealed that she had a history of diabetic retinopathy of her left eye and had undergone a laser treatment for this. This was complicated by retinal detachment followed by three reattachment procedures, all of which
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ultimately failed. She finally underwent intravitreal injection of silicone oil in 2009. Given this history and the non-dependent nature of the intraventricular masses, these findings were thought to represent migration of silicone oil material from the left vitreous humor through the left optic
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nerve and chiasm to the ventricular system. Subsequently, a non-contrast CT of the brain was performed with the patient in the prone position, demonstrating movement of the intraventricular
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hyperdensities from the frontal horns to the posterior bodies of the lateral ventricles (Figure 1D). The patient’s symptoms resolved with normalization of her blood pressure and blood sugar, suggesting that the imaging findings of intraventricular silicone migration were incidental to her presenting symptoms. She was ultimately discharged home in good condition and remained
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asymptomatic at six-month follow-up. Subsequent review of the patient’s past medical records from an outside hospital found a previous MRI brain from two years prior that showed these
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DISCUSSION
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findings to be stable (Figure 2C).
Intravitreal injection is commonly used as part of a vitrectomy to tamponade the retina
into place for the treatment of retinal detachment.1 While complications are rare, there have been several cases in the literature of migration of the silicone oil from the vitrea to the cerebral ventricles (Table 1).
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As with our case, reported cases of intraventricular silicon oil were found after brain imaging due to various neurologic symptoms. Presenting neurologic symptoms ranged from headache, syncope, dizziness, sensory or motor changes, seizures, and stroke. As with our case,
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however, intraventricular silicone was presumed to be incidental to the presenting symptoms in most reported cases. In only one case, reported by Hruby et al.,14 was the intraventricular
silicone thought to be symptomatic. In this case, the patient presented with headache and was
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found to have silicone within the bilateral frontal horns and third ventricle. The patient was also found to have elevated intracranial pressure (ICP). Given this latter finding, a
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ventriculoperitoneal shunt was placed and the patient’s headaches resolved. In this case, the mechanism underlying this patient’s elevated ICP was not clear. A possible cause is obstruction of the cerebrospinal fluid (CSF) pathway by a silicone oil globule. While this would not be expected from silicone within the lateral ventricles, silicone within the third or fourth ventricles
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could theoretically obstruct the CSF pathways. Furthermore, since the silicone globules “float” within the ventricles, their position is not static and may only intermittently obstruct the CSF pathways. Interestingly, silicone oil injection into the foramen magnum of animals as an
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experimental model of hydrocephalus.22 Importantly, studies of this experimental model also showed no significant inflammatory reaction within the meninges or ependyma,22 suggesting that
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an inflammatory response does not occur with intraventricular migration of silicone oil. Additionally, Swami et al.18 reported no evidence of inflammation on a CSF cell count performed on a patient with intraventricular silicone. Imaging characteristics of intraventricular silicone have been well-characterized.23 On CT, silicone is typically globular and hyperdense, with Houndsfield units ranging from the 50s130s.10,12,15,16,18,21,23 On MRI, silicone signal characteristics vary based on imaging protocols and
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density of a given silicone oil,7 but intraventricular silicone is typically hypointense compared to CSF on T2 imaging, hyperintense on T1 and T2/FLAIR imaging, and non-enhancing. In our case, we demonstrated peripheral gradient susceptibility and silicone may also demonstrate
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chemical shift on spin echo or gradient echo imaging.13,16 In addition, proton MRI spectroscopy has also been used to differentiate intraventricular silicone from blood.12 The density of silicone oil is less than CSF so intraventricular silicone tends to be found in a non-dependent position,
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especially when present in the lateral ventricles. This is an important contrast to intraventricular blood, which often layers in a dependent fashion within the ventricles. Another important
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imaging characteristic of intraventricular silicone is its ability to change position within the ventricles with position changes. This is typically demonstrated as with our case by performing brain imaging with the patient in prone position. Spontaneous movement of intraventricular silicone between interval supine scans has also been reported.10,11,14-21
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The mechanism of silicone oil migration from the vitreous to the cerebral ventricles is not known. Silicone is thought to enter the optic nerve via the lamina cribrosa.24 Papp et al.5 demonstrated silicone oil bubbles within the optic nerve of an enucleated eye as well as within
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the perineural subarachnoid space surrounding the optic nerve within the orbit. From there, the silicone oil theoretically has access to the intradural subarachnoid space where it may coalesce
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within the ventricles.8 In fact, Jabbour et al.13 demonstrated evidence of silicone within the suprasellar subarachnoid space. Despite that finding, Jabbour et al. proposed a slightly different mechanism of ventricular migration where the silicone migrates through the optic nerve, chiasm, and optic tract to the thalamus where it may then migrate into the lateral ventricle via the choroidal fissure. This theory is supported by evidence of silicone oil within the optic pathway from the optic nerve to the optic tract, although we are not aware of any reports of silicone
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within the thalamus itself. It is believed that silicone initially enters the optic nerve due to elevated intraocular pressure or in the setting of anatomic optic nerve head abnormalities.6,25 The frequency of ventricular migration of silicone oil is thought be very low. Not only are there
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few reported cases of this phenomenon but Kiilgaard et al.26 prospectively reviewed 19 patients with intravitreal silicone oil and found no evidence of silicone migration within the optic
pathway, subarachnoid space, or cerebral ventricles on MRIs performed between 61-225 days
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after silicone injection. However, the largely asymptomatic nature of this phenomenon may suggest that the true incidence is higher than reported. Interestingly, review of the literature
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reveals that this phenomenon can be seen up to 25 years after the initial intravitreal injection.
CONCLUSION
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Migration of intravitreal silicone oil into the subarachnoid or ventricular space is a rare phenomenon. It is generally thought to be benign although there is one case report of elevated ICP in the setting of intraventricular silicone that was treated with CSF diversion. Importantly,
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the CT imaging findings of subarachnoid or intraventricular silicone can mimic more dangerous neurosurgical pathologies, such as acute subarachnoid or intraventricular hemorrhage, tumor, or
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colloid cyst. Recognition of associated CT imaging findings can help make the diagnosis early in a patient’s workup and avoid unnecessary or invasive studies. Such findings include a nondependent location within the ventricle, additional hyperdensity within the globe and optic pathways, and movement of the intraventricular hyperdensities on prone imaging or even spontaneous movement on repeated imaging. In addition, MRI can be used to further confirm the diagnosis.
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References Fraser S, Steel D. Retinal detachment. BMJ Clin Evid. 2010;2010.
2.
Russo A, Morescalchi F, Donati S, et al. Heavy and standard silicone oil: intraocular
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1.
inflammation. Int Ophthalmol. 2017. 3.
Ni C, Wang WJ, Albert DM, Schepens CL. Intravitreous silicone injection. Histopathologic findings in a human eye after 12 years. Arch Ophthalmol.
Shields CL, Eagle RC, Jr. Pseudo-Schnabel's cavernous degeneration of the optic nerve
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4.
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1983;101(9):1399-1401.
secondary to intraocular silicone oil. Arch Ophthalmol. 1989;107(5):714-717. 5.
Papp A, Toth J, Kerenyi T, Jackel M, Suveges I. Silicone oil in the subarachnoidal space-a possible route to the brain? Pathol Res Pract. 2004;200(3):247-252.
6.
Grzybowski A, Pieczynski J, Ascaso FJ. Neuronal complications of intravitreal silicone
7.
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oil: an updated review. Acta Ophthalmol. 2014;92(3):201-204. Williams RL, Beatty RL, Kanal E, Weissman JL. MR imaging of intraventricular silicone: case report. Radiology. 1999;212(1):151-154. Eller AW, Friberg TR, Mah F. Migration of silicone oil into the brain: a complication of
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8.
9.
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intraocular silicone oil for retinal tamponade. Am J Ophthalmol. 2000;129(5):685-688. Fangtian D, Rongping D, Lin Z, Weihong Y. Migration of intraocular silicone into the
cerebral ventricles. Am J Ophthalmol. 2005;140(1):156-158.
10.
Yu JT, Apte RS. A case of intravitreal silicone oil migration to the central nervous system. Retina. 2005;25(6):791-793.
11.
Kuhn F, Kover F, Szabo I, Mester V. Intracranial migration of silicone oil from an eye with optic pit. Graefes Arch Clin Exp Ophthalmol. 2006;244(10):1360-1362.
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12.
Tatewaki Y, Kurihara N, Sato A, Suzuki I, Ezura M, Takahashi S. Silicone oil migrating from intraocular tamponade into the ventricles: case report with magnetic resonance image findings. J Comput Assist Tomogr. 2011;35(1):43-45. Jabbour P, Hanna A, Rosenwasser R. Migration of silicone oil in the cerebral intraventricular system. Neurologist. 2011;17(2):109-110.
14.
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13.
Hruby PM, Poley PR, Terp PA, Thorell WE, Margalit E. Headaches secondary to
Cases Brief Rep. 2013;7(3):288-290.
Chang CC, Chang HS, Toh CH. Intraventricular silicone oil. J Neurosurg. 2013;118(5):1127-1129.
16.
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15.
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intraventricular silicone oil successfully managed with ventriculoperitoneal shunt. Retin
Campbell G, Milbourne S, Salman UA, Khan MA. Ocular silicone oil in the lateral cerebral ventricle. J Clin Neurosci. 2013;20(9):1312-1313.
Cosgrove J, Djoukhadar I, Warren D, Jamieson S. Migration of intraocular silicone oil
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17.
into the brain. Pract Neurol. 2013;13(6):418-419. 18.
Swami MP, Bhootra K, Shah C, Mevada B. Intraventricular silicone oil mimicking a
19.
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colloid cyst. Neurol India. 2015;63(4):564-566. Chiao D, Ksendzovsky A, Buell T, Sheehan J, Newman S, Wintermark M.
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Intraventricular migration of silicone oil: A mimic of traumatic and neoplastic pathology. J Clin Neurosci. 2015;22(7):1205-1207.
20.
Dababneh H, Hussain M, Bashir A. Mystery case: A case of oil in ventricles: deception for intraventricular hemorrhage. Neurology. 2015;85(4):e30-31.
21.
Mathis S, Boissonnot M, Tasu JP, Simonet C, Ciron J, Neau JP. Intraventricular Silicone Oil: A Case Report. Medicine (Baltimore). 2016;95(1):e2359.
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22.
Wisniewski H, Weller RO, Terry RD. Experimental hydrocephalus produced by the subarachnoid infusion of silicone oil. J Neurosurg. 1969;31(1):10-14.
23.
Mathews VP, Elster AD, Barker PB, Buff BL, Haller JA, Greven CM. Intraocular
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silicone oil: in vitro and in vivo MR and CT characteristics. AJNR Am J Neuroradiol. 1994;15(2):343-347. 24.
Saitoh A, Taniguchi H, Gong H, Ohira A, Amemiya T, Baba T. Long-term effect on
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optic nerve of silicone oil tamponade in rabbits: histological and EDXA findings. Eye (Lond). 2002;16(2):171-176.
Grzybowski A, Ascaso J. Central nervous system migration of intraocular silicone oil:
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25.
The role of elevated intraocular pressure and congenital optic nerve abnormalities. J Clin Neurosci. 2016;24:168.
Kiilgaard JF, Milea D, Logager V, la Cour M. Cerebral migration of intraocular silicone
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oil: an MRI study. Acta Ophthalmol. 2011;89(6):522-525.
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26.
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FIGURE LEGENDS Figure 1. Axial non-contrast head CT images with the patient in a standard supine position (A-
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C) demonstrating non-dependent hyperdensities within the frontal horns of the lateral ventricles (A) as well as hyperdensities within the left globe (B and D), optic nerve (B, arrow head), and left optic chiasm (C, arrow). The lateral ventricular hyperdensities shifted when the patient was
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imaged in a prone position (D).
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Figure 2. Axial T2/FLAIR (A) and gradient echo (GRE, B) images demonstrate hyperintense T2/FLAIR signal and peripheral gradient susceptibility in the silicone globules within the frontal horns of the lateral ventricles. These findings are overall stable compared to a previous MRI
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study from two years prior (axial T2/FLAIR, C).
Figure 3. Axial T2/FLAIR (A) and maximum intensity projection susceptibility weighted (MIP SWI, B) images demonstrate abnormal T2/FLAIR signal and blooming along the left optic nerve
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to the level of optic chiasm (arrows), which parallel the signals of the silicone oil tamponade in
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the left eye (arrowheads).
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Table 1. Literature review of case reports of intracerebral migration of silicone oil
42
M/F
M
Eye
Presentation
Initial location
Left
Peripheral neuropathy
Intraventricular (frontal horn)
NR
NR
HU
Spontaneous movement?
No
Silicone in optic pathway
Time from silicone injection
Prone imaging?
Treatment
Optic nerve and chiasm
15mo
Yes
No
NR
8mo
Yes
No
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Williams et al., 19997 and Eller et al., 20008
Age (years)
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Study
Fangtian et al., 20059
62
F
Left
LOC
Intraventircular (lateral, 3rd, and 4th ventricles)
Yu and Apte, 200510
47
M
Right
Altered mental status
Intraventricular
90
Yes
Globe
~1yr
No
No
Kuhn et al., 200611
28
F
Both
HA
Intraventricular (frontal horn)
NR
Yes
Optic chiasm and tract
13yr
Yes
No
Tatewaki et al., 201112
66
F
Left
HA, lower extremity weakness
Intraventricular (frontal horn)
80
No
Optic nerve
NR
No
No
Jabbour et al., 201113
72
M
Right
HA
Intraventircular (frontal horn)
NR
No
Optic nerve and tract
15yr
No
No
NR
Yes
NR
5yr
Yes
Yes
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No
51
M
NR
HA
Chang et al., 201315
58
F
Left
Dizziness, HA
Intraventricular (4th and right frontal horn)
108
Yes
Optic nerve*
10-16yr
Yes
No
Campbell et al., 201316
40
M
Right
Seizure
Intraventricular
89
Yes
Globe
NR
Yes
No
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Hruby et al., 201314
Intraventricular (bilateral frontal horns, optic recess of 3rd)
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18
Swami et al., 2015
74
68
F
M
Left
Both
HA
Intraventricular (frontal horn)
NR
Yes
UTI
Intraventricular (3rd near foramen of Monro)
5060
Yes
Globe, optic nerve
20yr
No
No
Globes
9-10yr
No
No
Globe, optic nerve, chiasm, radiation
NR
Yes
No
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Cosgrove et al., 201317
80
F
Left
Syncope, fall
Dababneh et al., 201520
73
F
NR
HA, dizziness, syncope
Intraventricular (left temporal horn, 4th)
NR
Yes
NR
25yr
No
No
Ischemic stroke
Intraventricular (bilateral frontal horns and L temporal horn)
98
Yes
Globe, optic nerve
38mo
No
No
F
Left
NR, not reported UTI, urinary tract infection LOC, loss of consciousness
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HA, headache
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*Seen on initial scan but not on subsequent scan.
Yes
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82
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Mathis et al., 201621
NR
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Chiao et al., 201519
Intraventricular (bilateral frontal horns)
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Highlights •
Intraocular injection of silicone oil is sometimes used for the treatment of retinal detachment Intraocular silicone oil can migrate into the cerebral ventricular system where it appears
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•
hyperdense on CT imaging and can be confused with other intracranial pathologies, such as intraventricular hemorrhage, tumor, or colloid cyst
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Clinical history and careful review of imaging findings can help distinguish
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intraventricular silicone from other intracranial pathologies
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•
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Abbreviations CT, computed tomography CTA, computed tomography angiography
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CSF, cerebrospinal fluid GRE, gradient echo ICP, intracranial pressure
MRI, magnetic resonance imaging
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T2/FLAIR, T2/fluid attenuated inversion recovery
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MIP SWI, maximum intensity projection susceptibility weighted imaging
S1878-8750(18)30765-4
DOI:
10.1016/j.wneu.2018.04.049
Reference:
WNEU 7885
To appear in:
World Neurosurgery
Received Date: 18 February 2018 Revised Date:
8 April 2018
Accepted Date: 9 April 2018
Please cite this article as: Potts MB, Wu AC, Rusinak DJ, Kesavabhotla K, Jahromi BS, Seeing floaters – a case report and literature review of intraventricular migration of silicone oil tamponade material for retinal detachment, World Neurosurgery (2018), doi: 10.1016/j.wneu.2018.04.049. 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
Seeing floaters – a case report and literature review of intraventricular migration of
RI PT
silicone oil tamponade material for retinal detachment
Matthew B. Potts,1,2 Alex C. Wu, MD,2 David J. Rusinak, MD,2 Kartik Kesavabhotla, MD,1 Babak S. Jahromi, MD, PhD1,2
Departments of Neurological Surgery and 2Radiology
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1
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Northwestern Memorial Hospital
Northwestern University Feinberg School of Medicine
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Corresponding author:
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Chicago, IL 60611, USA.
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Matthew B. Potts, MD
676 N. St. Clair St., Suite 2210 Chicago, IL 60611
Email: [email protected] Phone: 312-695-6200 Fax: 312-695-0225
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ABSTRACT Background. Intraocular injection of silicone oil is commonly performed during vitrectomy to
RI PT
tamponade the retina in place for treatment of retinal detachment. Although rare, this intravitreal silicone can migrate through the optic nerve and chiasm and enter the cerebral ventricles.
Case description. Here we present a case report of a patient presenting with headache and
SC
intraventricular hyperdensities on computed tomography imaging raising concern for
intraventricular hemorrhage. The intraventricular hyperdensities, however, were in a non-
M AN U
dependent location and moved to a new non-dependent location when a repeat imaging was performed with the patient in a prone position. We provide a literature review of this phenomenon and discuss the relevant CT and MRI findings.
Conclusion. Intraocular silicone can rarely migrate into the cerebral ventricular system. Careful
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review of the clinical history and imaging findings can help distinguish this from other, more
BACKGROUND
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dangerous intracranial pathologies.
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Intravitreal injection of silicone oil is commonly performed during vitrectomy to tamponade the retina in place for treatment of retinal detachment.1 Such oils are viscous and hydrophobic silicone polymers or monomers and have been used for this purpose since the 1960s.2 A rare phenomenon associated with this treatment is migration of the silicone oil into the optic nerve and chiasm3-6 and even into the cerebral ventricular system.7-21 The mechanism of this migration is not well understood and intraventricular silicone oil can be confused for other intracranial pathologies such as intraventricular hemorrhage, tumor, or colloid cyst.18-20
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Awareness of this phenomenon is therefore important for neurosurgeons to avoid unnecessary workup or interventions.
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Here we present a case of intraventricular migration of silicone tamponade material that was initially diagnosed as intraventricular hemorrhage. We also review the literature, describe
SC
the imaging findings and techniques, and discuss the possible mechanisms of this phenomenon.
CASE
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A 56 year-old woman with multiple medical comorbidities, including insulin-dependent diabetes, was transferred to our institution with acute onset headache and face parasthesias and a report of intraventricular hemorrhage on non-contrast head computed tomography (CT). She was also hypertensive and hypoglycemic on presentation. A CT angiogram (CTA) upon arrival
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found no vascular abnormalities but again demonstrated non-dependent globular hyperdense foci within the frontal horns of both lateral ventricles (Figure 1A) as well as hyperdensity within the vitrea of the left eye and along the course of the left optic nerve and chiasm (Figure 1B and C,
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respectively). Magnetic resonance imaging (MRI) of the brain revealed the non-dependent intraventricular masses to be non-enhancing and hyperintense on T1 and T2/fluid attenuated
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inversion recovery (T2/FLAIR) imaging (Figure 2A). These masses also demonstrated peripheral gradient susceptibility (Figure 2B). In addition, there was hyperintense T2/FLAIR signal within the left vitreous chamber as well as abnormal hyperintense T2/FLAIR signal abnormality, intrinsic T1 shortening, and susceptibility along the left optic nerve that extended into the left aspect of the optic chiasm (Figure 3).
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Further review of the patient’s past medical history revealed that she had a history of diabetic retinopathy of her left eye and had undergone a laser treatment for this. This was complicated by retinal detachment followed by three reattachment procedures, all of which
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ultimately failed. She finally underwent intravitreal injection of silicone oil in 2009. Given this history and the non-dependent nature of the intraventricular masses, these findings were thought to represent migration of silicone oil material from the left vitreous humor through the left optic
SC
nerve and chiasm to the ventricular system. Subsequently, a non-contrast CT of the brain was performed with the patient in the prone position, demonstrating movement of the intraventricular
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hyperdensities from the frontal horns to the posterior bodies of the lateral ventricles (Figure 1D). The patient’s symptoms resolved with normalization of her blood pressure and blood sugar, suggesting that the imaging findings of intraventricular silicone migration were incidental to her presenting symptoms. She was ultimately discharged home in good condition and remained
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asymptomatic at six-month follow-up. Subsequent review of the patient’s past medical records from an outside hospital found a previous MRI brain from two years prior that showed these
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DISCUSSION
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findings to be stable (Figure 2C).
Intravitreal injection is commonly used as part of a vitrectomy to tamponade the retina
into place for the treatment of retinal detachment.1 While complications are rare, there have been several cases in the literature of migration of the silicone oil from the vitrea to the cerebral ventricles (Table 1).
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As with our case, reported cases of intraventricular silicon oil were found after brain imaging due to various neurologic symptoms. Presenting neurologic symptoms ranged from headache, syncope, dizziness, sensory or motor changes, seizures, and stroke. As with our case,
RI PT
however, intraventricular silicone was presumed to be incidental to the presenting symptoms in most reported cases. In only one case, reported by Hruby et al.,14 was the intraventricular
silicone thought to be symptomatic. In this case, the patient presented with headache and was
SC
found to have silicone within the bilateral frontal horns and third ventricle. The patient was also found to have elevated intracranial pressure (ICP). Given this latter finding, a
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ventriculoperitoneal shunt was placed and the patient’s headaches resolved. In this case, the mechanism underlying this patient’s elevated ICP was not clear. A possible cause is obstruction of the cerebrospinal fluid (CSF) pathway by a silicone oil globule. While this would not be expected from silicone within the lateral ventricles, silicone within the third or fourth ventricles
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could theoretically obstruct the CSF pathways. Furthermore, since the silicone globules “float” within the ventricles, their position is not static and may only intermittently obstruct the CSF pathways. Interestingly, silicone oil injection into the foramen magnum of animals as an
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experimental model of hydrocephalus.22 Importantly, studies of this experimental model also showed no significant inflammatory reaction within the meninges or ependyma,22 suggesting that
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an inflammatory response does not occur with intraventricular migration of silicone oil. Additionally, Swami et al.18 reported no evidence of inflammation on a CSF cell count performed on a patient with intraventricular silicone. Imaging characteristics of intraventricular silicone have been well-characterized.23 On CT, silicone is typically globular and hyperdense, with Houndsfield units ranging from the 50s130s.10,12,15,16,18,21,23 On MRI, silicone signal characteristics vary based on imaging protocols and
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density of a given silicone oil,7 but intraventricular silicone is typically hypointense compared to CSF on T2 imaging, hyperintense on T1 and T2/FLAIR imaging, and non-enhancing. In our case, we demonstrated peripheral gradient susceptibility and silicone may also demonstrate
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chemical shift on spin echo or gradient echo imaging.13,16 In addition, proton MRI spectroscopy has also been used to differentiate intraventricular silicone from blood.12 The density of silicone oil is less than CSF so intraventricular silicone tends to be found in a non-dependent position,
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especially when present in the lateral ventricles. This is an important contrast to intraventricular blood, which often layers in a dependent fashion within the ventricles. Another important
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imaging characteristic of intraventricular silicone is its ability to change position within the ventricles with position changes. This is typically demonstrated as with our case by performing brain imaging with the patient in prone position. Spontaneous movement of intraventricular silicone between interval supine scans has also been reported.10,11,14-21
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The mechanism of silicone oil migration from the vitreous to the cerebral ventricles is not known. Silicone is thought to enter the optic nerve via the lamina cribrosa.24 Papp et al.5 demonstrated silicone oil bubbles within the optic nerve of an enucleated eye as well as within
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the perineural subarachnoid space surrounding the optic nerve within the orbit. From there, the silicone oil theoretically has access to the intradural subarachnoid space where it may coalesce
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within the ventricles.8 In fact, Jabbour et al.13 demonstrated evidence of silicone within the suprasellar subarachnoid space. Despite that finding, Jabbour et al. proposed a slightly different mechanism of ventricular migration where the silicone migrates through the optic nerve, chiasm, and optic tract to the thalamus where it may then migrate into the lateral ventricle via the choroidal fissure. This theory is supported by evidence of silicone oil within the optic pathway from the optic nerve to the optic tract, although we are not aware of any reports of silicone
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within the thalamus itself. It is believed that silicone initially enters the optic nerve due to elevated intraocular pressure or in the setting of anatomic optic nerve head abnormalities.6,25 The frequency of ventricular migration of silicone oil is thought be very low. Not only are there
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few reported cases of this phenomenon but Kiilgaard et al.26 prospectively reviewed 19 patients with intravitreal silicone oil and found no evidence of silicone migration within the optic
pathway, subarachnoid space, or cerebral ventricles on MRIs performed between 61-225 days
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after silicone injection. However, the largely asymptomatic nature of this phenomenon may suggest that the true incidence is higher than reported. Interestingly, review of the literature
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reveals that this phenomenon can be seen up to 25 years after the initial intravitreal injection.
CONCLUSION
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Migration of intravitreal silicone oil into the subarachnoid or ventricular space is a rare phenomenon. It is generally thought to be benign although there is one case report of elevated ICP in the setting of intraventricular silicone that was treated with CSF diversion. Importantly,
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the CT imaging findings of subarachnoid or intraventricular silicone can mimic more dangerous neurosurgical pathologies, such as acute subarachnoid or intraventricular hemorrhage, tumor, or
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colloid cyst. Recognition of associated CT imaging findings can help make the diagnosis early in a patient’s workup and avoid unnecessary or invasive studies. Such findings include a nondependent location within the ventricle, additional hyperdensity within the globe and optic pathways, and movement of the intraventricular hyperdensities on prone imaging or even spontaneous movement on repeated imaging. In addition, MRI can be used to further confirm the diagnosis.
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References Fraser S, Steel D. Retinal detachment. BMJ Clin Evid. 2010;2010.
2.
Russo A, Morescalchi F, Donati S, et al. Heavy and standard silicone oil: intraocular
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1.
inflammation. Int Ophthalmol. 2017. 3.
Ni C, Wang WJ, Albert DM, Schepens CL. Intravitreous silicone injection. Histopathologic findings in a human eye after 12 years. Arch Ophthalmol.
Shields CL, Eagle RC, Jr. Pseudo-Schnabel's cavernous degeneration of the optic nerve
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4.
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1983;101(9):1399-1401.
secondary to intraocular silicone oil. Arch Ophthalmol. 1989;107(5):714-717. 5.
Papp A, Toth J, Kerenyi T, Jackel M, Suveges I. Silicone oil in the subarachnoidal space-a possible route to the brain? Pathol Res Pract. 2004;200(3):247-252.
6.
Grzybowski A, Pieczynski J, Ascaso FJ. Neuronal complications of intravitreal silicone
7.
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oil: an updated review. Acta Ophthalmol. 2014;92(3):201-204. Williams RL, Beatty RL, Kanal E, Weissman JL. MR imaging of intraventricular silicone: case report. Radiology. 1999;212(1):151-154. Eller AW, Friberg TR, Mah F. Migration of silicone oil into the brain: a complication of
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8.
9.
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intraocular silicone oil for retinal tamponade. Am J Ophthalmol. 2000;129(5):685-688. Fangtian D, Rongping D, Lin Z, Weihong Y. Migration of intraocular silicone into the
cerebral ventricles. Am J Ophthalmol. 2005;140(1):156-158.
10.
Yu JT, Apte RS. A case of intravitreal silicone oil migration to the central nervous system. Retina. 2005;25(6):791-793.
11.
Kuhn F, Kover F, Szabo I, Mester V. Intracranial migration of silicone oil from an eye with optic pit. Graefes Arch Clin Exp Ophthalmol. 2006;244(10):1360-1362.
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12.
Tatewaki Y, Kurihara N, Sato A, Suzuki I, Ezura M, Takahashi S. Silicone oil migrating from intraocular tamponade into the ventricles: case report with magnetic resonance image findings. J Comput Assist Tomogr. 2011;35(1):43-45. Jabbour P, Hanna A, Rosenwasser R. Migration of silicone oil in the cerebral intraventricular system. Neurologist. 2011;17(2):109-110.
14.
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13.
Hruby PM, Poley PR, Terp PA, Thorell WE, Margalit E. Headaches secondary to
Cases Brief Rep. 2013;7(3):288-290.
Chang CC, Chang HS, Toh CH. Intraventricular silicone oil. J Neurosurg. 2013;118(5):1127-1129.
16.
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15.
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intraventricular silicone oil successfully managed with ventriculoperitoneal shunt. Retin
Campbell G, Milbourne S, Salman UA, Khan MA. Ocular silicone oil in the lateral cerebral ventricle. J Clin Neurosci. 2013;20(9):1312-1313.
Cosgrove J, Djoukhadar I, Warren D, Jamieson S. Migration of intraocular silicone oil
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17.
into the brain. Pract Neurol. 2013;13(6):418-419. 18.
Swami MP, Bhootra K, Shah C, Mevada B. Intraventricular silicone oil mimicking a
19.
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colloid cyst. Neurol India. 2015;63(4):564-566. Chiao D, Ksendzovsky A, Buell T, Sheehan J, Newman S, Wintermark M.
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Intraventricular migration of silicone oil: A mimic of traumatic and neoplastic pathology. J Clin Neurosci. 2015;22(7):1205-1207.
20.
Dababneh H, Hussain M, Bashir A. Mystery case: A case of oil in ventricles: deception for intraventricular hemorrhage. Neurology. 2015;85(4):e30-31.
21.
Mathis S, Boissonnot M, Tasu JP, Simonet C, Ciron J, Neau JP. Intraventricular Silicone Oil: A Case Report. Medicine (Baltimore). 2016;95(1):e2359.
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22.
Wisniewski H, Weller RO, Terry RD. Experimental hydrocephalus produced by the subarachnoid infusion of silicone oil. J Neurosurg. 1969;31(1):10-14.
23.
Mathews VP, Elster AD, Barker PB, Buff BL, Haller JA, Greven CM. Intraocular
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silicone oil: in vitro and in vivo MR and CT characteristics. AJNR Am J Neuroradiol. 1994;15(2):343-347. 24.
Saitoh A, Taniguchi H, Gong H, Ohira A, Amemiya T, Baba T. Long-term effect on
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optic nerve of silicone oil tamponade in rabbits: histological and EDXA findings. Eye (Lond). 2002;16(2):171-176.
Grzybowski A, Ascaso J. Central nervous system migration of intraocular silicone oil:
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25.
The role of elevated intraocular pressure and congenital optic nerve abnormalities. J Clin Neurosci. 2016;24:168.
Kiilgaard JF, Milea D, Logager V, la Cour M. Cerebral migration of intraocular silicone
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oil: an MRI study. Acta Ophthalmol. 2011;89(6):522-525.
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26.
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FIGURE LEGENDS Figure 1. Axial non-contrast head CT images with the patient in a standard supine position (A-
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C) demonstrating non-dependent hyperdensities within the frontal horns of the lateral ventricles (A) as well as hyperdensities within the left globe (B and D), optic nerve (B, arrow head), and left optic chiasm (C, arrow). The lateral ventricular hyperdensities shifted when the patient was
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imaged in a prone position (D).
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Figure 2. Axial T2/FLAIR (A) and gradient echo (GRE, B) images demonstrate hyperintense T2/FLAIR signal and peripheral gradient susceptibility in the silicone globules within the frontal horns of the lateral ventricles. These findings are overall stable compared to a previous MRI
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study from two years prior (axial T2/FLAIR, C).
Figure 3. Axial T2/FLAIR (A) and maximum intensity projection susceptibility weighted (MIP SWI, B) images demonstrate abnormal T2/FLAIR signal and blooming along the left optic nerve
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to the level of optic chiasm (arrows), which parallel the signals of the silicone oil tamponade in
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the left eye (arrowheads).
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Table 1. Literature review of case reports of intracerebral migration of silicone oil
42
M/F
M
Eye
Presentation
Initial location
Left
Peripheral neuropathy
Intraventricular (frontal horn)
NR
NR
HU
Spontaneous movement?
No
Silicone in optic pathway
Time from silicone injection
Prone imaging?
Treatment
Optic nerve and chiasm
15mo
Yes
No
NR
8mo
Yes
No
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Williams et al., 19997 and Eller et al., 20008
Age (years)
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Study
Fangtian et al., 20059
62
F
Left
LOC
Intraventircular (lateral, 3rd, and 4th ventricles)
Yu and Apte, 200510
47
M
Right
Altered mental status
Intraventricular
90
Yes
Globe
~1yr
No
No
Kuhn et al., 200611
28
F
Both
HA
Intraventricular (frontal horn)
NR
Yes
Optic chiasm and tract
13yr
Yes
No
Tatewaki et al., 201112
66
F
Left
HA, lower extremity weakness
Intraventricular (frontal horn)
80
No
Optic nerve
NR
No
No
Jabbour et al., 201113
72
M
Right
HA
Intraventircular (frontal horn)
NR
No
Optic nerve and tract
15yr
No
No
NR
Yes
NR
5yr
Yes
Yes
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No
51
M
NR
HA
Chang et al., 201315
58
F
Left
Dizziness, HA
Intraventricular (4th and right frontal horn)
108
Yes
Optic nerve*
10-16yr
Yes
No
Campbell et al., 201316
40
M
Right
Seizure
Intraventricular
89
Yes
Globe
NR
Yes
No
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Hruby et al., 201314
Intraventricular (bilateral frontal horns, optic recess of 3rd)
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18
Swami et al., 2015
74
68
F
M
Left
Both
HA
Intraventricular (frontal horn)
NR
Yes
UTI
Intraventricular (3rd near foramen of Monro)
5060
Yes
Globe, optic nerve
20yr
No
No
Globes
9-10yr
No
No
Globe, optic nerve, chiasm, radiation
NR
Yes
No
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Cosgrove et al., 201317
80
F
Left
Syncope, fall
Dababneh et al., 201520
73
F
NR
HA, dizziness, syncope
Intraventricular (left temporal horn, 4th)
NR
Yes
NR
25yr
No
No
Ischemic stroke
Intraventricular (bilateral frontal horns and L temporal horn)
98
Yes
Globe, optic nerve
38mo
No
No
F
Left
NR, not reported UTI, urinary tract infection LOC, loss of consciousness
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HA, headache
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*Seen on initial scan but not on subsequent scan.
Yes
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82
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Mathis et al., 201621
NR
SC
Chiao et al., 201519
Intraventricular (bilateral frontal horns)
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Highlights •
Intraocular injection of silicone oil is sometimes used for the treatment of retinal detachment Intraocular silicone oil can migrate into the cerebral ventricular system where it appears
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•
hyperdense on CT imaging and can be confused with other intracranial pathologies, such as intraventricular hemorrhage, tumor, or colloid cyst
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Clinical history and careful review of imaging findings can help distinguish
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intraventricular silicone from other intracranial pathologies
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•
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Abbreviations CT, computed tomography CTA, computed tomography angiography
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CSF, cerebrospinal fluid GRE, gradient echo ICP, intracranial pressure
MRI, magnetic resonance imaging
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T2/FLAIR, T2/fluid attenuated inversion recovery
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MIP SWI, maximum intensity projection susceptibility weighted imaging