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Intraventricular migration of silicone oil: A mimic of traumatic and neoplastic pathology
Case Reports / Journal of Clinical Neuroscience 22 (2015) 1205–1207
1205
Intraventricular migration of silicone oil: A mimic of traumatic and neoplastic pathology David Chiao a,⇑, Alexander Ksendzovsky b,d, Thomas Buell b, Jason Sheehan b, Steven Newman b,c, Max Wintermark e a
Neuroradiology Division, Department of Radiology and Medical Imaging, University of Virginia, 1215 Lee Street, Post Office Box 800170, Charlottesville, VA 22908-0170, USA Department of Neurosurgery, University of Virginia, Charlottesville, VA, USA Department of Opthalmology, University of Virginia, Charlottesville, VA, USA d Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA e Department of Radiology, Stanford University School of Medicine, Stanford, CA, USA b c
a r t i c l e
i n f o
Article history: Received 30 January 2015 Accepted 4 February 2015
Keywords: Complications Extraocular Imaging Intraocular Intraventricular Oil Silicone
a b s t r a c t We describe an 80-year-old woman with intraventricular silicone oil mimicking traumatic pathology upon presentation to the emergency department after a ground-level fall. Intraventricular migration of silicone oil from prior intraocular endotamponade is rare having only been described in a handful of case reports. While it has a unique and characteristic appearance on imaging, intraventricular silicone oil can be confused with intraventricular hemorrhage or calcified ventricular neoplasms. Recognition and differentiation of intraventricular silicone oil from more sinister pathology is essential for the radiologist, neurologist and neurosurgeon and can be done with routine head CT scan. We discuss the imaging findings of intraventricular silicone oil and review the current understanding of this unusual phenomenon. Ó 2015 Elsevier Ltd. All rights reserved.
1. Introduction Silicone oil is a commonly employed method for intraocular endotamponade of complicated retinal detachments [1]. Typically, 1000–5000 centistroke-viscosity silicone oil is used to treat retinal detachments associated with proliferative retinopathy, giant retinal tears, cytomegalovirus infection and trauma [2]. While early animal studies suggested good tolerance to silicone oil, a number of ocular complications have since been described including silicone oil keratopathy, conjunctival inclusion cysts, cataract formation, glaucoma, optic atrophy, reproliferation of membranes beneath the oil interface and subretinal migration [3–5]. Recently, intracranial migration of silicone oil has also been described in the literature. In the current work, we describe a woman with intraventricular silicone oil mimicking traumatic pathology upon presentation to the emergency department after a ground-level fall. We then discuss the imaging findings of intraventricular silicone oil and review the current understanding of this unusual phenomenon.
Non-contrast enhanced CT scan (NECT) of the head showed small volume subarachnoid hemorrhage and a parenchymal contusion at the contrecoup site in the left parasagittal frontal lobe (Fig. 1A). The ventricular system was notable for smooth, rounded hyperdensities in the non-dependent frontal horns (Fig. 1B). In addition, hyperdense material was identified in the left globe, left optic nerve, left optic chiasm and left optic radiation (Fig. 2). On further review of the electronic medical record, the patient had a remote history of left intraocular silicone oil endotamponade at an outside institution. The diagnosis of intraventricular silicone oil was made and confirmed with subsequent prone imaging which demonstrated movement of the hyperdensities into the nondependent lateral ventricles (Fig. 1C). Follow-up imaging 1 month later demonstrated interval resolution of the parenchymal contusion with persistent intraventricular silicone oil.
3. Discussion 3.1. Pathophysiology
2. Case report An 80-year-old woman with medical history significant for hypertension, hyperlipidemia, congestive heart failure and atrial fibrillation, presented to the emergency department after sustaining a concussion from a ground-level fall. The patient’s husband reported that the patient stood up after watching TV, became lightheaded, fell backwards and hit the back of her head. Upon admission, the patient denied nausea, vomiting or vision changes. Physical examination was significant for a small posterior scalp laceration and a benign neurological exam. A head CT scan was ordered to exclude acute intracranial hemorrhage. ⇑ Corresponding author. Tel.: +1 804 514 3530. E-mail address: [email protected] (D. Chiao).
Intraventricular migration is a known but rare complication of intraocular silicone oil endotamponade having been described in only 11 case reports to our knowledge (Table 1) [6,7]. The precise mechanism of silicone oil migration is not well understood. One hypothesis is that silicone oil first enters the optic nerve via a pseudo-Schnabel cavernous degeneration mechanism in which silicone oil migrates from the vitreous humor through the lamina cribosa into the optic nerve [6,8]. It subsequently gains access to the subarachnoid spaces around the optic nerve due to persistent increased intraocular pressure, eventually migrating into the ventricular system via the foramina of Magendie and Luschka [5–7,9]. This progression of migration was described visually in a case report by Chang et al. in which serial imaging of a patient treated with intraocular silicone oil endotamponade demonstrated gradual migration of silicone oil from the optic nerve to the lateral
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Case Reports / Journal of Clinical Neuroscience 22 (2015) 1205–1207
Fig. 1. (A) Axial non-contrast head CT scan of an 80-year-old woman with intraventricular silicone oil demonstrating small volume subarachnoid hemorrhage/parenchymal contusion at the contrecoup site in the left parasagittal frontal lobe (arrow). A hyperdensity is partially visualized in the non-dependent right lateral ventricle (thick arrow). (B) Axial non-contrast head CT scan in the same patient better demonstrating rounded hyperdensities in the non-dependent lateral ventricles (arrows). (C) Follow-up noncontrast head CT scan 6 h later in the prone position in the same patient. There is interval shifting of the rounded hyperdensities into the non-dependent lateral ventricles (arrows).
Fig. 2. Axial non-contrast head CT scan of an 80-year-old woman with intraventricular silicone oil demonstrating hyperdense material in the (A) left globe, (A) left optic nerve, (B) left optic chiasm, and (C) left optic radiation (arrows).
ventricles [7]. Another hypothesis by Fangtian et al. posits that deep cupping of the optic disc from chronically increased intraocular pressure allows silicone oil to directly enter the subarachnoid space by breaking through the cerebral pia [10]. Another hypothesis by Knecht et al. suggests that active physiologic processes facilitate silicone oil migration [1]. A final hypothesis is that silicone oil migration occurs in patients with anatomic variants such as an optic pit or coloboma [11]. While distinct mechanisms for intraventricular silicone oil migration exist, there may be overlap among them. However, due to the limited evidence supporting any one of the mechanisms, the degree and significance of this overlap is currently unknown.
NECT scans, silicone oil appears hyperdense, with an attenuation higher than hemorrhage, usually measuring 70–140 Hounsfield units (HU). In addition, silicone oil characteristically forms convex fluid-fluid interfaces in the non-dependent ventricles (due to the high surface tension and low specific gravity of silicon oil) [6,7,11,12]. On MRI, silicone oil is hyperintense on T1-weighted imaging with a prominent chemical shift artifact [13]. Signal intensity on T2-weighted imaging is variable. It can be iso-, hypo-, or hyper-intense but in general, the higher the viscosity of the silicone oil the more hypointense the signal on T2-weighted imaging [13].
3.3. Management and clinical course 3.2. Imaging findings Intraventricular silicone oil has a characteristic appearance on imaging and can be diagnosed with routine CT scans or MRI. On
In the majority of case reports, patients with intraventricular silicone oil were asymptomatic [7]. Currently, there is no consensus on the treatment or follow-up imaging of patients with
M M 42 47 1 1 Williams et al. [13] Yu et al. [16]
F 66 1 Tatewaki et al. (2011)
F 15 1 Kuhn et al. [11]
CMV = cytomegalovirus, cs = centistroke-viscosity, F = female, Hyper = hyperintense, Hypo = hypointense, HU = Hounsfield units, M = male, NR = not reported, RD = retinal detachment, T1 = T1-weighted MRI, T2 = T2-weighted MRI.
Yes Yes Yes Yes Hypo NR Yes Yes NA 90 5000 NR
15 months 1 year
Yes Yes
No Yes
Hyper NR
Yes Yes Hyper Yes 80 Yes NR
NR
NR
Headache, lower extremity weakness Peripheral neuropathy Altered mental status
Hypo
Yes NR NR Yes NR Yes NR
6 years
Yes
Headaches
NR
Yes Yes Fall NR NR NR M 72 1 Jabbour et al. [14]
M F 42 62 1 1 Eller et al. [5] Fangtian et al. [10]
M F 1 1 Chen et al. [15] Cosgrove et al. [9]
39 74
RD (CMV) RD (diabetic retinopathy) RD (diabetic retinopathy) RD (cystic macular edema) Diabetic retinopathy RD (CMV) Vitreous hemorrhage (diabetic retinopathy)
5000 5000
NR Yes NR Yes
NR
Yes Yes Yes Yes Yes Yes
NR NR Yes Yes NR NR Yes Yes Peripheral neuropathy Dizziness
NR NR
Yes Yes Yes NR Hyper Hyper Yes Yes 82 NR Yes Yes NR NR
NR Approximately 20 years 6.5 months 8 months
NR NR
Falls, headaches, nausea Headaches
Intermediate Intermediate
Yes Yes Yes Yes Hypo Hypo Hyper Hyper Yes Yes 89 108 Yes Yes Seizure Headache, dizziness NR NR NR 10 years NR NR
NR RD (diabetic retinopathy) Diabetic retinopathy RD M F 1 1 Campbell et al. [6] Chang et al. [7]
40 58
Indication for endotamponade Sex Age Patients Authors
Table 1 Reported patients with intraventricular migration of silicone oil
Type of silicone oil (cs)
Endotamponade time
Glaucoma
T1 MRI Attenuation (HU) CT scan Indication for imaging
T2
Chemical shift
Nondependent/ mobile
Case Reports / Journal of Clinical Neuroscience 22 (2015) 1205–1207
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intraventricular silicone oil and most patients are simply observed on a clinical basis [2,7,14]. However, extraocular silicone oil is not completely benign. Chronic granulomatous inflammatory reaction has been reported in the regions of intraneural silicone oil on histopathologic studies, raising the possibility of silicone oil associated nerve damage [3,8]. Therefore, it has generally been recommended that intraocular pressure be well controlled in patients with intraocular silicone oil, regardless of the visual potential, in the hopes of avoiding extraocular migration [7,12]. Nevertheless, given that the incidence of intraventricular migration is rare, most authors do not recommend modifying treatment protocols of intraocular silicone oil endotamponade solely on the potential risk of intraventricular migration. As the cohort of patients treated with intraocular silicone oil endotamponade increases in number and age, there is likely to be an increase in the number of cases of intraventricular silicone oil. It will therefore be increasingly important to recognize silicone oil migration on imaging and differentiate it from traumatic or neoplastic pathology. Conflicts of Interest/Disclosures The authors declare that they have no financial or other conflicts of interest in relation to this research and its publication. References [1] Knecht P, Groscurth P, Ziegler U, et al. Is silicone oil optic neuropathy caused by high intraocular pressure alone? A semi-biological model. Br J Ophthalmol 2007;91:1293–5. [2] Grzybowski A, Pieczynski J, Ascaso FJ. Neuronal complications of intravitreal silicone oil: an updated review. Acta Ophthalmol 2014;92:201–4. [3] Biswas J, Verma A, Davda MD, et al. Intraocular tissue migration of silicone oil after silicone oil tamponade: a histopathological study of enucleated silicone oil-filled eyes. Indian J Ophthalmol 2008;56:425–8. [4] Armaly MF. Ocular tolerance to silicones. I. Replacement of aqueous and vitreous by silicone fluids. Arch Ophthalmol 1962;68:390–5. [5] Eller AW, Friberg TR, Mah F. Migration of silicone oil into the brain: a complication of intraocular silicone oil for retinal tamponade. Am J Ophthalmol 2000;129:685–8. [6] Campbell G, Milbourne S, Salman UA, et al. Ocular silicone oil in the lateral cerebral ventricle. J Clin Neurosci 2013;20:1312–3. [7] Chang CC, Chang HS, Toh CH. Intraventricular silicone oil. J Neurosurg 2013;118:1127–9. [8] Budde M, Cursiefen C, Holbach LM, et al. Silicone oil-associated optic nerve degeneration. Am J Ophthalmol 2001;131:392–4. [9] Cosgrove J, Djoukhadar I, Warren D, et al. Migration of intraocular silicone oil into the brain. Pract Neurol 2013;13:418–9. [10] Fangtian D, Rongping D, Lin Z, et al. Migration of intraocular silicone into the cerebral ventricles. Am J Ophthalmol 2005;140:156–8. [11] Kuhn F, Kover F, Szabo I, et al. Intracranial migration of silicone oil from an eye with optic pit. Graefes Arch Clin Exp Ophthalmol 2006;244:1360–2. [12] Eckle D, Kampik A, Hintschich C, et al. Visual field defect in association with chiasmal migration of intraocular silicone oil. Br J Ophthalmol 2005;89:918–20. [13] Williams RL, Beatty RL, Kanal E, et al. MR imaging of intraventricular silicone: case report. Radiology 1999;212:151–4. [14] Jabbour P, Hanna A, Rosenwasser R. Migration of silicone oil in the cerebral intraventricular system. Neurologist 2011;17:109–10. [15] Chen JX, Nidecker AE, Aygun N, et al. Intravitreal silicone oil migration into the subarachnoid space and ventricles: a case report and review of literature. Eur J Radiol Extra 2011;78:e81–3. [16] Yu JT, Apte RS. A case of intravitreal silicone oil migration to the central nervous system. Retina 2005;25:791–3. http://dx.doi.org/10.1016/j.jocn.2015.02.003
1205
Intraventricular migration of silicone oil: A mimic of traumatic and neoplastic pathology David Chiao a,⇑, Alexander Ksendzovsky b,d, Thomas Buell b, Jason Sheehan b, Steven Newman b,c, Max Wintermark e a
Neuroradiology Division, Department of Radiology and Medical Imaging, University of Virginia, 1215 Lee Street, Post Office Box 800170, Charlottesville, VA 22908-0170, USA Department of Neurosurgery, University of Virginia, Charlottesville, VA, USA Department of Opthalmology, University of Virginia, Charlottesville, VA, USA d Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA e Department of Radiology, Stanford University School of Medicine, Stanford, CA, USA b c
a r t i c l e
i n f o
Article history: Received 30 January 2015 Accepted 4 February 2015
Keywords: Complications Extraocular Imaging Intraocular Intraventricular Oil Silicone
a b s t r a c t We describe an 80-year-old woman with intraventricular silicone oil mimicking traumatic pathology upon presentation to the emergency department after a ground-level fall. Intraventricular migration of silicone oil from prior intraocular endotamponade is rare having only been described in a handful of case reports. While it has a unique and characteristic appearance on imaging, intraventricular silicone oil can be confused with intraventricular hemorrhage or calcified ventricular neoplasms. Recognition and differentiation of intraventricular silicone oil from more sinister pathology is essential for the radiologist, neurologist and neurosurgeon and can be done with routine head CT scan. We discuss the imaging findings of intraventricular silicone oil and review the current understanding of this unusual phenomenon. Ó 2015 Elsevier Ltd. All rights reserved.
1. Introduction Silicone oil is a commonly employed method for intraocular endotamponade of complicated retinal detachments [1]. Typically, 1000–5000 centistroke-viscosity silicone oil is used to treat retinal detachments associated with proliferative retinopathy, giant retinal tears, cytomegalovirus infection and trauma [2]. While early animal studies suggested good tolerance to silicone oil, a number of ocular complications have since been described including silicone oil keratopathy, conjunctival inclusion cysts, cataract formation, glaucoma, optic atrophy, reproliferation of membranes beneath the oil interface and subretinal migration [3–5]. Recently, intracranial migration of silicone oil has also been described in the literature. In the current work, we describe a woman with intraventricular silicone oil mimicking traumatic pathology upon presentation to the emergency department after a ground-level fall. We then discuss the imaging findings of intraventricular silicone oil and review the current understanding of this unusual phenomenon.
Non-contrast enhanced CT scan (NECT) of the head showed small volume subarachnoid hemorrhage and a parenchymal contusion at the contrecoup site in the left parasagittal frontal lobe (Fig. 1A). The ventricular system was notable for smooth, rounded hyperdensities in the non-dependent frontal horns (Fig. 1B). In addition, hyperdense material was identified in the left globe, left optic nerve, left optic chiasm and left optic radiation (Fig. 2). On further review of the electronic medical record, the patient had a remote history of left intraocular silicone oil endotamponade at an outside institution. The diagnosis of intraventricular silicone oil was made and confirmed with subsequent prone imaging which demonstrated movement of the hyperdensities into the nondependent lateral ventricles (Fig. 1C). Follow-up imaging 1 month later demonstrated interval resolution of the parenchymal contusion with persistent intraventricular silicone oil.
3. Discussion 3.1. Pathophysiology
2. Case report An 80-year-old woman with medical history significant for hypertension, hyperlipidemia, congestive heart failure and atrial fibrillation, presented to the emergency department after sustaining a concussion from a ground-level fall. The patient’s husband reported that the patient stood up after watching TV, became lightheaded, fell backwards and hit the back of her head. Upon admission, the patient denied nausea, vomiting or vision changes. Physical examination was significant for a small posterior scalp laceration and a benign neurological exam. A head CT scan was ordered to exclude acute intracranial hemorrhage. ⇑ Corresponding author. Tel.: +1 804 514 3530. E-mail address: [email protected] (D. Chiao).
Intraventricular migration is a known but rare complication of intraocular silicone oil endotamponade having been described in only 11 case reports to our knowledge (Table 1) [6,7]. The precise mechanism of silicone oil migration is not well understood. One hypothesis is that silicone oil first enters the optic nerve via a pseudo-Schnabel cavernous degeneration mechanism in which silicone oil migrates from the vitreous humor through the lamina cribosa into the optic nerve [6,8]. It subsequently gains access to the subarachnoid spaces around the optic nerve due to persistent increased intraocular pressure, eventually migrating into the ventricular system via the foramina of Magendie and Luschka [5–7,9]. This progression of migration was described visually in a case report by Chang et al. in which serial imaging of a patient treated with intraocular silicone oil endotamponade demonstrated gradual migration of silicone oil from the optic nerve to the lateral
1206
Case Reports / Journal of Clinical Neuroscience 22 (2015) 1205–1207
Fig. 1. (A) Axial non-contrast head CT scan of an 80-year-old woman with intraventricular silicone oil demonstrating small volume subarachnoid hemorrhage/parenchymal contusion at the contrecoup site in the left parasagittal frontal lobe (arrow). A hyperdensity is partially visualized in the non-dependent right lateral ventricle (thick arrow). (B) Axial non-contrast head CT scan in the same patient better demonstrating rounded hyperdensities in the non-dependent lateral ventricles (arrows). (C) Follow-up noncontrast head CT scan 6 h later in the prone position in the same patient. There is interval shifting of the rounded hyperdensities into the non-dependent lateral ventricles (arrows).
Fig. 2. Axial non-contrast head CT scan of an 80-year-old woman with intraventricular silicone oil demonstrating hyperdense material in the (A) left globe, (A) left optic nerve, (B) left optic chiasm, and (C) left optic radiation (arrows).
ventricles [7]. Another hypothesis by Fangtian et al. posits that deep cupping of the optic disc from chronically increased intraocular pressure allows silicone oil to directly enter the subarachnoid space by breaking through the cerebral pia [10]. Another hypothesis by Knecht et al. suggests that active physiologic processes facilitate silicone oil migration [1]. A final hypothesis is that silicone oil migration occurs in patients with anatomic variants such as an optic pit or coloboma [11]. While distinct mechanisms for intraventricular silicone oil migration exist, there may be overlap among them. However, due to the limited evidence supporting any one of the mechanisms, the degree and significance of this overlap is currently unknown.
NECT scans, silicone oil appears hyperdense, with an attenuation higher than hemorrhage, usually measuring 70–140 Hounsfield units (HU). In addition, silicone oil characteristically forms convex fluid-fluid interfaces in the non-dependent ventricles (due to the high surface tension and low specific gravity of silicon oil) [6,7,11,12]. On MRI, silicone oil is hyperintense on T1-weighted imaging with a prominent chemical shift artifact [13]. Signal intensity on T2-weighted imaging is variable. It can be iso-, hypo-, or hyper-intense but in general, the higher the viscosity of the silicone oil the more hypointense the signal on T2-weighted imaging [13].
3.3. Management and clinical course 3.2. Imaging findings Intraventricular silicone oil has a characteristic appearance on imaging and can be diagnosed with routine CT scans or MRI. On
In the majority of case reports, patients with intraventricular silicone oil were asymptomatic [7]. Currently, there is no consensus on the treatment or follow-up imaging of patients with
M M 42 47 1 1 Williams et al. [13] Yu et al. [16]
F 66 1 Tatewaki et al. (2011)
F 15 1 Kuhn et al. [11]
CMV = cytomegalovirus, cs = centistroke-viscosity, F = female, Hyper = hyperintense, Hypo = hypointense, HU = Hounsfield units, M = male, NR = not reported, RD = retinal detachment, T1 = T1-weighted MRI, T2 = T2-weighted MRI.
Yes Yes Yes Yes Hypo NR Yes Yes NA 90 5000 NR
15 months 1 year
Yes Yes
No Yes
Hyper NR
Yes Yes Hyper Yes 80 Yes NR
NR
NR
Headache, lower extremity weakness Peripheral neuropathy Altered mental status
Hypo
Yes NR NR Yes NR Yes NR
6 years
Yes
Headaches
NR
Yes Yes Fall NR NR NR M 72 1 Jabbour et al. [14]
M F 42 62 1 1 Eller et al. [5] Fangtian et al. [10]
M F 1 1 Chen et al. [15] Cosgrove et al. [9]
39 74
RD (CMV) RD (diabetic retinopathy) RD (diabetic retinopathy) RD (cystic macular edema) Diabetic retinopathy RD (CMV) Vitreous hemorrhage (diabetic retinopathy)
5000 5000
NR Yes NR Yes
NR
Yes Yes Yes Yes Yes Yes
NR NR Yes Yes NR NR Yes Yes Peripheral neuropathy Dizziness
NR NR
Yes Yes Yes NR Hyper Hyper Yes Yes 82 NR Yes Yes NR NR
NR Approximately 20 years 6.5 months 8 months
NR NR
Falls, headaches, nausea Headaches
Intermediate Intermediate
Yes Yes Yes Yes Hypo Hypo Hyper Hyper Yes Yes 89 108 Yes Yes Seizure Headache, dizziness NR NR NR 10 years NR NR
NR RD (diabetic retinopathy) Diabetic retinopathy RD M F 1 1 Campbell et al. [6] Chang et al. [7]
40 58
Indication for endotamponade Sex Age Patients Authors
Table 1 Reported patients with intraventricular migration of silicone oil
Type of silicone oil (cs)
Endotamponade time
Glaucoma
T1 MRI Attenuation (HU) CT scan Indication for imaging
T2
Chemical shift
Nondependent/ mobile
Case Reports / Journal of Clinical Neuroscience 22 (2015) 1205–1207
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intraventricular silicone oil and most patients are simply observed on a clinical basis [2,7,14]. However, extraocular silicone oil is not completely benign. Chronic granulomatous inflammatory reaction has been reported in the regions of intraneural silicone oil on histopathologic studies, raising the possibility of silicone oil associated nerve damage [3,8]. Therefore, it has generally been recommended that intraocular pressure be well controlled in patients with intraocular silicone oil, regardless of the visual potential, in the hopes of avoiding extraocular migration [7,12]. Nevertheless, given that the incidence of intraventricular migration is rare, most authors do not recommend modifying treatment protocols of intraocular silicone oil endotamponade solely on the potential risk of intraventricular migration. As the cohort of patients treated with intraocular silicone oil endotamponade increases in number and age, there is likely to be an increase in the number of cases of intraventricular silicone oil. It will therefore be increasingly important to recognize silicone oil migration on imaging and differentiate it from traumatic or neoplastic pathology. Conflicts of Interest/Disclosures The authors declare that they have no financial or other conflicts of interest in relation to this research and its publication. References [1] Knecht P, Groscurth P, Ziegler U, et al. Is silicone oil optic neuropathy caused by high intraocular pressure alone? A semi-biological model. Br J Ophthalmol 2007;91:1293–5. [2] Grzybowski A, Pieczynski J, Ascaso FJ. Neuronal complications of intravitreal silicone oil: an updated review. Acta Ophthalmol 2014;92:201–4. [3] Biswas J, Verma A, Davda MD, et al. Intraocular tissue migration of silicone oil after silicone oil tamponade: a histopathological study of enucleated silicone oil-filled eyes. Indian J Ophthalmol 2008;56:425–8. [4] Armaly MF. Ocular tolerance to silicones. I. Replacement of aqueous and vitreous by silicone fluids. Arch Ophthalmol 1962;68:390–5. [5] Eller AW, Friberg TR, Mah F. Migration of silicone oil into the brain: a complication of intraocular silicone oil for retinal tamponade. Am J Ophthalmol 2000;129:685–8. [6] Campbell G, Milbourne S, Salman UA, et al. Ocular silicone oil in the lateral cerebral ventricle. J Clin Neurosci 2013;20:1312–3. [7] Chang CC, Chang HS, Toh CH. Intraventricular silicone oil. J Neurosurg 2013;118:1127–9. [8] Budde M, Cursiefen C, Holbach LM, et al. Silicone oil-associated optic nerve degeneration. Am J Ophthalmol 2001;131:392–4. [9] Cosgrove J, Djoukhadar I, Warren D, et al. Migration of intraocular silicone oil into the brain. Pract Neurol 2013;13:418–9. [10] Fangtian D, Rongping D, Lin Z, et al. Migration of intraocular silicone into the cerebral ventricles. Am J Ophthalmol 2005;140:156–8. [11] Kuhn F, Kover F, Szabo I, et al. Intracranial migration of silicone oil from an eye with optic pit. Graefes Arch Clin Exp Ophthalmol 2006;244:1360–2. [12] Eckle D, Kampik A, Hintschich C, et al. Visual field defect in association with chiasmal migration of intraocular silicone oil. Br J Ophthalmol 2005;89:918–20. [13] Williams RL, Beatty RL, Kanal E, et al. MR imaging of intraventricular silicone: case report. Radiology 1999;212:151–4. [14] Jabbour P, Hanna A, Rosenwasser R. Migration of silicone oil in the cerebral intraventricular system. Neurologist 2011;17:109–10. [15] Chen JX, Nidecker AE, Aygun N, et al. Intravitreal silicone oil migration into the subarachnoid space and ventricles: a case report and review of literature. Eur J Radiol Extra 2011;78:e81–3. [16] Yu JT, Apte RS. A case of intravitreal silicone oil migration to the central nervous system. Retina 2005;25:791–3. http://dx.doi.org/10.1016/j.jocn.2015.02.003