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Tuberous sclerosis with homonymous hemianopsia
Correspondence Tuberous sclerosis with homonymous hemianopsia
V
igabatrin (VGB) is used widely in the treatment of tuberous sclerosis because of its effectiveness in intractable seizures. However, this agent has been known to cause adverse visual field changes, which usually occur in the form of peripheral field constriction.1,2 Cortical tubers, composed of abnormal glial and neural cells, are typically located at the grey–white matter interface, commonly in the frontal and parietal lobes. The number of tubers may correlate with the severity of seizures.3 However, these brain lesions have rarely been reported to cause visual field defects. We report a patient with tuberous sclerosis who was taking VGB and had calcified tubers located on the occipital lobe and visual cortex, which caused incongruous homonymous hemianopsia. To our knowledge, a homonymous hemianopsia secondary to a central nervous system (CNS) tuber has not been previously reported, and so we report the details of this case. An 11-year-old girl whose condition was diagnosed as tuberous sclerosis was given VGB for the treatment of epilepsy. The patient had the typical skin lesions of tuberous sclerosis: adenoma sebaceum, a forehead Shagreen patch, and ash-leaf macules on the lower limbs (Fig. 1). Brain lesions on MRI and a history of 4 seizures contributed to the diagnosis of tuberous sclerosis. The patient was given VGB, known to cause visual field constriction. Therefore, ophthalmologic evaluation was required. On fundus examination, there were multiple subretinal hamartomas and a tuber with a ghost vessel next to the optic nerve (Fig. 1). Brain MRI showed multiple cortical tubers of high signal intensity. A 5 × 2 cm sized, serpiginous, calcific lesion was found on the left occipital lobe. Automated perimetry showed right homonymous hemianopsia, and MRI showed a correlative left occipital calcific lesion (Fig. 2). In this case, homonymous hemianopsia was of an incomplete and incongruent form. Harrington4 described
Fig. 1—Adenoma sebaceum (upper left); Shagreen patches (middle left); an ash-leaf spot (upper right); characteristic multiple harmatomas in the fundus (black arrow) and an optic disc tuber with a ghost vessel (white arrow).
the rule about congruity of hemianopic defect: congruity of a hemianopsia argues for a lesion in the visual cortex or posterior visual radiation, whereas incongruity typically accompanies a lesion in the anterior visual radiations or the optic tract; the more congruent is the homonymous hemianopsia, the more posterior is the lesion. However, Kedar et al.5 found that 16%–23% of the lesions involving occipital cortex or posterior optic radiation produced incongruent homonymous hemianopsia and at least 50% of the lesions in other locations produced the congruent type. Therefore, they suggested that the rule of congruency should be used cautiously. VGB is a highly effective antiepileptic drug, especially in patients with otherwise intractable seizures. It is widely accepted as the first-line treatment for infantile spasms, especially those occurring secondary to tuberous sclerosis, and as an add-on therapy for medically resistant localization-related childhood epilepsies. VGB mediates its antiepileptic effect through irreversible inhibition of brain gamma-aminobutyric acid transaminase. Its wide clinical implementation has been prevented by its ability to cause visual field narrowing.1,2 Long-term VGB-related visual field changes usually occur in the form of peripheral field constriction, more commonly in the nasal field than in the temporal field.6,7 A CNS tuber leading to homonymous hemianopsia has never been reported. A bilateral visual field defect respecting the vertical meridian is a definite sign of a visual pathway or visual cortex lesion.
Fig. 2—T2W transverse image (upper left) and FLAIR image (upper right) showing large, serpiginous calcification in the left occipital lobe (arrow). Right incongruous homonymous hemianopsia was present on perimetry at initial examination and after 4 months. (T2W, T2 weighted; FLAIR, fluid-attenuated inversion recovery). CAN J OPHTHALMOL—VOL. 44, NO. 6, 2009
717
Correspondence In this case, right incongruous homonymous hemianopsia and a corresponding large, calcific brain lesion in the left occipital lobe made it easy to rule out VGB-induced field constriction. However, if the field defect does not correspond to the brain lesion and it is manifest as peripheral field constriction, VGB-associated visual change is a more likely diagnosis. This case also emphasizes the importance of obtaining evaluations of visual function, including visual field tests, before beginning VGB therapy and of clinical correlation when attributing an abnormal test result, in this case visual field defects, to a particular cause—structural abnormality or pharmacologic toxicity. REFERENCES 1. Eke T, Talbot JF, Lawden MC. Severe persistent visual field constriction associated with vigabatrin. BMJ 1997:314;180–1. 2. Toggweiler S, Wieser HG. Concentric visual field restriction under vigabatrin therapy: extent depends on the duration of drug intake. Seizure 2001;10:420–3. 3. Crino PB, Henske EP. New developments in the neurobiology of the tuberous sclerosis complex. Neurology 1999;53:1384–90. 4. Harrington DO. Visual field character in temporal and
Central retinal vein occlusion after nonperforating sclerectomy without mitomycin
T
he association between central retinal vein occlusion (CRVO) and increased intraocular pressure (IOP) is widely known.1 After glaucoma filtering surgery, a retinal vascular occlusion would be improbable because the IOP decreases significantly in the early postoperative period. This complication has been reported previously after trabeculectomy surgery.2–4 Because mitomycin (MMC) was used in all these cases, a relation between its diffusion into the vitreous cavity and the development of the CRVO was suggested. We present a case of a 55-year-old woman who developed a CRVO in the early postoperative period after a nonperforating deep sclerectomy without MMC and without any identifiable cardiovascular risk factor. A healthy 55-year-old woman with advanced primary
Fig. 1—Visual field (Humphrey) showed superior and inferior severe arcuate scotoma in both eyes. (DM, mean deviation; DSM, pattern standard deviation.)
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CAN J OPHTHALMOL—VOL. 44, NO. 6, 2009
occipital lobe lesions. Localizing values of congruity and incongruity in incomplete homonimus hemianopia. Arch Ophthalmol 1961;66:778–92. 5. Kedar S, Zhang X, Lynn MJ, Newman N, Biousse V. Congruency in homonymous hemianopia. Am J Ophthalmol 2007;143:772–80. 6. Lawthom C, Smith PE, Wild JM. Nasal retinal nerve fiber layer attenuation: a biomarker for vigabatrin toxicity. Ophthalmology 2009;116:565–71. Epub Jan. 24, 2009. 7. John RA, Rimmer EM, Williams J, Cole G, Fowler LJ, Richens A. Micro-vacuolation in rat brains after long term administration of GABA transaminase inhibitors. Comparison of effects of ethanolamine-O-sulphate and vigabatrin. Biochem Pharmacol 1987;36:1467–73.
Jay won Rhim, Chungkwon Yoo, Seung-Hyun Kim Department of Ophthalmology, Korea University College of Medicine, Ansan, South Korea Correspondence to Seung-Hyun Kim, MD: [email protected] Can J Ophthalmol 2009;44:717–8 doi:10.3129/i09-193
open-angle glaucoma, treated unsuccessfully with 2 antiglaucoma medications, underwent nonperforating deep sclerectomy OS. Preoperatively, the best-corrected visual acuity was 1/1 OR and 9/10 OS, and the IOP was 25 OR and 27 OS. The visual field showed superior and inferior severe arcuate scotoma in both eyes (Fig. 1) and the cup/disc ratio was 0.8 OR and 0.9 OS. Her medical history did not disclose any cardiovascular risk factors or medical treatments. On postoperative day 1, visual acuity was unchanged at 9/10, the filtration bleb was elevated, and IOP was 4 mm Hg. Six days later, visual acuity was counting fingers, IOP was 8 mm Hg, and ophthalmoscopic examination showed a CRVO with intraretinal hemorrhages in all 4 quadrants (Fig. 2). Based on the fluorescein angiography, it was classified as perfused CRVO. The macular thickness measured
Fig. 2—Ophthalmoscopic evaluation showed intraretinal hemorrhages in all 4 quadrants, dilation, and increased tortuosity of the retinal veins.
V
igabatrin (VGB) is used widely in the treatment of tuberous sclerosis because of its effectiveness in intractable seizures. However, this agent has been known to cause adverse visual field changes, which usually occur in the form of peripheral field constriction.1,2 Cortical tubers, composed of abnormal glial and neural cells, are typically located at the grey–white matter interface, commonly in the frontal and parietal lobes. The number of tubers may correlate with the severity of seizures.3 However, these brain lesions have rarely been reported to cause visual field defects. We report a patient with tuberous sclerosis who was taking VGB and had calcified tubers located on the occipital lobe and visual cortex, which caused incongruous homonymous hemianopsia. To our knowledge, a homonymous hemianopsia secondary to a central nervous system (CNS) tuber has not been previously reported, and so we report the details of this case. An 11-year-old girl whose condition was diagnosed as tuberous sclerosis was given VGB for the treatment of epilepsy. The patient had the typical skin lesions of tuberous sclerosis: adenoma sebaceum, a forehead Shagreen patch, and ash-leaf macules on the lower limbs (Fig. 1). Brain lesions on MRI and a history of 4 seizures contributed to the diagnosis of tuberous sclerosis. The patient was given VGB, known to cause visual field constriction. Therefore, ophthalmologic evaluation was required. On fundus examination, there were multiple subretinal hamartomas and a tuber with a ghost vessel next to the optic nerve (Fig. 1). Brain MRI showed multiple cortical tubers of high signal intensity. A 5 × 2 cm sized, serpiginous, calcific lesion was found on the left occipital lobe. Automated perimetry showed right homonymous hemianopsia, and MRI showed a correlative left occipital calcific lesion (Fig. 2). In this case, homonymous hemianopsia was of an incomplete and incongruent form. Harrington4 described
Fig. 1—Adenoma sebaceum (upper left); Shagreen patches (middle left); an ash-leaf spot (upper right); characteristic multiple harmatomas in the fundus (black arrow) and an optic disc tuber with a ghost vessel (white arrow).
the rule about congruity of hemianopic defect: congruity of a hemianopsia argues for a lesion in the visual cortex or posterior visual radiation, whereas incongruity typically accompanies a lesion in the anterior visual radiations or the optic tract; the more congruent is the homonymous hemianopsia, the more posterior is the lesion. However, Kedar et al.5 found that 16%–23% of the lesions involving occipital cortex or posterior optic radiation produced incongruent homonymous hemianopsia and at least 50% of the lesions in other locations produced the congruent type. Therefore, they suggested that the rule of congruency should be used cautiously. VGB is a highly effective antiepileptic drug, especially in patients with otherwise intractable seizures. It is widely accepted as the first-line treatment for infantile spasms, especially those occurring secondary to tuberous sclerosis, and as an add-on therapy for medically resistant localization-related childhood epilepsies. VGB mediates its antiepileptic effect through irreversible inhibition of brain gamma-aminobutyric acid transaminase. Its wide clinical implementation has been prevented by its ability to cause visual field narrowing.1,2 Long-term VGB-related visual field changes usually occur in the form of peripheral field constriction, more commonly in the nasal field than in the temporal field.6,7 A CNS tuber leading to homonymous hemianopsia has never been reported. A bilateral visual field defect respecting the vertical meridian is a definite sign of a visual pathway or visual cortex lesion.
Fig. 2—T2W transverse image (upper left) and FLAIR image (upper right) showing large, serpiginous calcification in the left occipital lobe (arrow). Right incongruous homonymous hemianopsia was present on perimetry at initial examination and after 4 months. (T2W, T2 weighted; FLAIR, fluid-attenuated inversion recovery). CAN J OPHTHALMOL—VOL. 44, NO. 6, 2009
717
Correspondence In this case, right incongruous homonymous hemianopsia and a corresponding large, calcific brain lesion in the left occipital lobe made it easy to rule out VGB-induced field constriction. However, if the field defect does not correspond to the brain lesion and it is manifest as peripheral field constriction, VGB-associated visual change is a more likely diagnosis. This case also emphasizes the importance of obtaining evaluations of visual function, including visual field tests, before beginning VGB therapy and of clinical correlation when attributing an abnormal test result, in this case visual field defects, to a particular cause—structural abnormality or pharmacologic toxicity. REFERENCES 1. Eke T, Talbot JF, Lawden MC. Severe persistent visual field constriction associated with vigabatrin. BMJ 1997:314;180–1. 2. Toggweiler S, Wieser HG. Concentric visual field restriction under vigabatrin therapy: extent depends on the duration of drug intake. Seizure 2001;10:420–3. 3. Crino PB, Henske EP. New developments in the neurobiology of the tuberous sclerosis complex. Neurology 1999;53:1384–90. 4. Harrington DO. Visual field character in temporal and
Central retinal vein occlusion after nonperforating sclerectomy without mitomycin
T
he association between central retinal vein occlusion (CRVO) and increased intraocular pressure (IOP) is widely known.1 After glaucoma filtering surgery, a retinal vascular occlusion would be improbable because the IOP decreases significantly in the early postoperative period. This complication has been reported previously after trabeculectomy surgery.2–4 Because mitomycin (MMC) was used in all these cases, a relation between its diffusion into the vitreous cavity and the development of the CRVO was suggested. We present a case of a 55-year-old woman who developed a CRVO in the early postoperative period after a nonperforating deep sclerectomy without MMC and without any identifiable cardiovascular risk factor. A healthy 55-year-old woman with advanced primary
Fig. 1—Visual field (Humphrey) showed superior and inferior severe arcuate scotoma in both eyes. (DM, mean deviation; DSM, pattern standard deviation.)
718
CAN J OPHTHALMOL—VOL. 44, NO. 6, 2009
occipital lobe lesions. Localizing values of congruity and incongruity in incomplete homonimus hemianopia. Arch Ophthalmol 1961;66:778–92. 5. Kedar S, Zhang X, Lynn MJ, Newman N, Biousse V. Congruency in homonymous hemianopia. Am J Ophthalmol 2007;143:772–80. 6. Lawthom C, Smith PE, Wild JM. Nasal retinal nerve fiber layer attenuation: a biomarker for vigabatrin toxicity. Ophthalmology 2009;116:565–71. Epub Jan. 24, 2009. 7. John RA, Rimmer EM, Williams J, Cole G, Fowler LJ, Richens A. Micro-vacuolation in rat brains after long term administration of GABA transaminase inhibitors. Comparison of effects of ethanolamine-O-sulphate and vigabatrin. Biochem Pharmacol 1987;36:1467–73.
Jay won Rhim, Chungkwon Yoo, Seung-Hyun Kim Department of Ophthalmology, Korea University College of Medicine, Ansan, South Korea Correspondence to Seung-Hyun Kim, MD: [email protected] Can J Ophthalmol 2009;44:717–8 doi:10.3129/i09-193
open-angle glaucoma, treated unsuccessfully with 2 antiglaucoma medications, underwent nonperforating deep sclerectomy OS. Preoperatively, the best-corrected visual acuity was 1/1 OR and 9/10 OS, and the IOP was 25 OR and 27 OS. The visual field showed superior and inferior severe arcuate scotoma in both eyes (Fig. 1) and the cup/disc ratio was 0.8 OR and 0.9 OS. Her medical history did not disclose any cardiovascular risk factors or medical treatments. On postoperative day 1, visual acuity was unchanged at 9/10, the filtration bleb was elevated, and IOP was 4 mm Hg. Six days later, visual acuity was counting fingers, IOP was 8 mm Hg, and ophthalmoscopic examination showed a CRVO with intraretinal hemorrhages in all 4 quadrants (Fig. 2). Based on the fluorescein angiography, it was classified as perfused CRVO. The macular thickness measured
Fig. 2—Ophthalmoscopic evaluation showed intraretinal hemorrhages in all 4 quadrants, dilation, and increased tortuosity of the retinal veins.