[Downloaded free from http://www.neurologyindia.com on Tuesday, June 09, 2015, IP: 61.16.135.116]
Letters to Editor
Vigabatrin‑induced reversible changes on magnetic resonance imaging of the brain Sir, Infantile spasms (ISs), a rare subtype of seizure disorder, manifests in infancy and early childhood. Vigabatrin (VGB), an irreversible inhibitor of γ‑amino‑butyric acid (GABA)
a
b
transaminase (GABA‑T), is a first‑line drug used in the management of ISs.[1] Here, we present an uncommon case of VGB‑induced reversible changes on magnetic resonance imaging (MRI). A 7‑month‑old girl presented with seizures at 3 months of age. Initially, the seizures were focal clonic and treated with carbamazepine. At 4 months of age, she developed IS and was started on VGB (135 mg/kg/day). An MRI of the brain was requested to evaluate the cause of IS. The patient had completed 6 weeks of VGB therapy at the time of the MRI study. Symmetric restricted diffusion was seen in the globi palladi, thalami and dorsal brainstem along the dorsal tegmental tracts [Figure 1]. Clinical reassessment showed no corresponding new symptoms or examination findings to explain the signal alterations in the deep grey nuclei and brainstem. Also noted were focal areas of polymicrogyria in the right frontal and left temporal lobes [Figure 2], explaining the probable etiology of IS. In view of the changes seen on MRI, VGB was withdrawn. A repeat MRI was performed 8 weeks after the withdrawal of VGB; it showed resolution of the above mentioned findings, establishing the reversible nature of these MRI changes [Figure 3]. A literature search showed VGB‑induced MRI changes in approximately one‑third of patients.[2] These were seen in children below 18 months of age and were demonstrated to be reversible.[3,4] No clinical changes were documented
c
d
e
f
Figure 1: Diffusion-weighted images (a–c) and apparent diffusion coefficient images (d–f) demonstrate a symmetrical restricted diffusion in the globi palladi, thalami and dorsal brainstem along the dorsal tegmental tracts 430
Figure 2: Oblique coronal T2-weighted magnetic resonance imaging shows polymicro-gyria in the left temporal lobe
Neurology India / May 2015 / Volume 63 / Issue 3
[Downloaded free from http://www.neurologyindia.com on Tuesday, June 09, 2015, IP: 61.16.135.116]
Letters to Editor
a
d
c
b
e
f
Figure 3: Follow-up magnetic resonance imaging. Diffusion-weighted images (a–c) and apparent diffusion coefficient images (d–f) demonstrate resolution of the diffusion abnormality in the globi palladi, thalami and dorsal brainstem along the dorsal tegmental tracts (as seen in Figure 1)
correlating with these imaging findings. A few studies attributed these findings to intra‑myelinic edema and microvacuolation as a result of fluid accumulation and separation of the outer layers of the myelin.[5] One study conducted by Simao et al., however, showed that axonal abnormalities might have contributed to the altered signal intensities on MRI rather than changes in myelin.[6] The precise etiology of these changes remains unclear. In conclusion, restricted diffusion in the deep gray nuclei and brainstem is an uncommon but documented finding in infants on VGB and should not be mistaken for a more ominous pathology. The neurologist/pediatrician and radiologist need to be aware of VGB‑induced reversible MRI changes, as misdiagnosis as mitochondrial or amino acid metabolism disorders may trigger unwarranted investigations and unnecessary concern for the family.
Charul Goyal, Tejas H. Kapadia, Pradnya Gadgil1, Darshana Sanghvi Departments of Radiology and 1Paediatric Neurology, Kokilaben Dhirubhai Ambani Hospital and Medical Research Institute, Mumbai, Maharashtra, India E‑mail: [email protected]
References 1. 2.
3.
Mitchell WG, Shah NS. Vigabatrin for infantile spasms. Pediatr Neurol 2002;27:161‑4. Pearl PL, Vezina LG, Saneto RP, McCarter R, Molloy‑Wells E, Heffron A, et al. Cerebral MRI abnormalities associated with vigabatrin therapy. Epilepsia 2009;50:184‑94. Wheless JW, Carmant L, Bebin M, Conry JA, Chiron C, Elterman RD,
4.
5.
6.
et al. Magnetic resonance imaging abnormalities associated with vigabatrin in patients with epilepsy. Epilepsia 2009;50:195‑205. Dracopoulos A, Widjaja E, Raybaud C, Westall CA, Snead OC 3rd. Vigabatrin‑associated reversible MRI signal changes in patients with infantile spasms. Epilepsia 2010;51:1297‑304. Cohen JA, Fisher RS, Brigell MG, Peyster RG, Sze G. The potential for vigabatrin‑induced intramyelinic edema in humans. Epilepsia 2000;41:148‑57. Simao GN, Zarei Mahmoodabadi S, Snead OC, Go C, Widjaja E. Abnormal axial diffusivity in the deep gray nuclei and dorsal brain stem in infantile spasm treated with vigabatrin. AJNR Am J Neuroradiol 2011;32:199‑203. Access this article online
Website:
Quick Response Code
www.neurologyindia.com DOI: 10.4103/0028-3886.158237 PMID: xxxxx
Ophthalmic artery occlusion with total ophthalmoplegia following spinal surgery Sir, Ocular complications following a non‑ocular surgery are uncommon but may be devastating. The incidence of perioperative vision loss (POVL) after non ocular surgery ranges from 0.013% for all surgeries to upto 0.2% for spinal surgeries.[1] The causes of the sudden visual loss
Neurology India / May 2015 / Volume 63 / Issue 3
431
Copyright of Neurology India is the property of Medknow Publications & Media Pvt. Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
Copyright of Neurology India is the property of Medknow Publications & Media Pvt. Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
Letters to Editor
Vigabatrin‑induced reversible changes on magnetic resonance imaging of the brain Sir, Infantile spasms (ISs), a rare subtype of seizure disorder, manifests in infancy and early childhood. Vigabatrin (VGB), an irreversible inhibitor of γ‑amino‑butyric acid (GABA)
a
b
transaminase (GABA‑T), is a first‑line drug used in the management of ISs.[1] Here, we present an uncommon case of VGB‑induced reversible changes on magnetic resonance imaging (MRI). A 7‑month‑old girl presented with seizures at 3 months of age. Initially, the seizures were focal clonic and treated with carbamazepine. At 4 months of age, she developed IS and was started on VGB (135 mg/kg/day). An MRI of the brain was requested to evaluate the cause of IS. The patient had completed 6 weeks of VGB therapy at the time of the MRI study. Symmetric restricted diffusion was seen in the globi palladi, thalami and dorsal brainstem along the dorsal tegmental tracts [Figure 1]. Clinical reassessment showed no corresponding new symptoms or examination findings to explain the signal alterations in the deep grey nuclei and brainstem. Also noted were focal areas of polymicrogyria in the right frontal and left temporal lobes [Figure 2], explaining the probable etiology of IS. In view of the changes seen on MRI, VGB was withdrawn. A repeat MRI was performed 8 weeks after the withdrawal of VGB; it showed resolution of the above mentioned findings, establishing the reversible nature of these MRI changes [Figure 3]. A literature search showed VGB‑induced MRI changes in approximately one‑third of patients.[2] These were seen in children below 18 months of age and were demonstrated to be reversible.[3,4] No clinical changes were documented
c
d
e
f
Figure 1: Diffusion-weighted images (a–c) and apparent diffusion coefficient images (d–f) demonstrate a symmetrical restricted diffusion in the globi palladi, thalami and dorsal brainstem along the dorsal tegmental tracts 430
Figure 2: Oblique coronal T2-weighted magnetic resonance imaging shows polymicro-gyria in the left temporal lobe
Neurology India / May 2015 / Volume 63 / Issue 3
[Downloaded free from http://www.neurologyindia.com on Tuesday, June 09, 2015, IP: 61.16.135.116]
Letters to Editor
a
d
c
b
e
f
Figure 3: Follow-up magnetic resonance imaging. Diffusion-weighted images (a–c) and apparent diffusion coefficient images (d–f) demonstrate resolution of the diffusion abnormality in the globi palladi, thalami and dorsal brainstem along the dorsal tegmental tracts (as seen in Figure 1)
correlating with these imaging findings. A few studies attributed these findings to intra‑myelinic edema and microvacuolation as a result of fluid accumulation and separation of the outer layers of the myelin.[5] One study conducted by Simao et al., however, showed that axonal abnormalities might have contributed to the altered signal intensities on MRI rather than changes in myelin.[6] The precise etiology of these changes remains unclear. In conclusion, restricted diffusion in the deep gray nuclei and brainstem is an uncommon but documented finding in infants on VGB and should not be mistaken for a more ominous pathology. The neurologist/pediatrician and radiologist need to be aware of VGB‑induced reversible MRI changes, as misdiagnosis as mitochondrial or amino acid metabolism disorders may trigger unwarranted investigations and unnecessary concern for the family.
Charul Goyal, Tejas H. Kapadia, Pradnya Gadgil1, Darshana Sanghvi Departments of Radiology and 1Paediatric Neurology, Kokilaben Dhirubhai Ambani Hospital and Medical Research Institute, Mumbai, Maharashtra, India E‑mail: [email protected]
References 1. 2.
3.
Mitchell WG, Shah NS. Vigabatrin for infantile spasms. Pediatr Neurol 2002;27:161‑4. Pearl PL, Vezina LG, Saneto RP, McCarter R, Molloy‑Wells E, Heffron A, et al. Cerebral MRI abnormalities associated with vigabatrin therapy. Epilepsia 2009;50:184‑94. Wheless JW, Carmant L, Bebin M, Conry JA, Chiron C, Elterman RD,
4.
5.
6.
et al. Magnetic resonance imaging abnormalities associated with vigabatrin in patients with epilepsy. Epilepsia 2009;50:195‑205. Dracopoulos A, Widjaja E, Raybaud C, Westall CA, Snead OC 3rd. Vigabatrin‑associated reversible MRI signal changes in patients with infantile spasms. Epilepsia 2010;51:1297‑304. Cohen JA, Fisher RS, Brigell MG, Peyster RG, Sze G. The potential for vigabatrin‑induced intramyelinic edema in humans. Epilepsia 2000;41:148‑57. Simao GN, Zarei Mahmoodabadi S, Snead OC, Go C, Widjaja E. Abnormal axial diffusivity in the deep gray nuclei and dorsal brain stem in infantile spasm treated with vigabatrin. AJNR Am J Neuroradiol 2011;32:199‑203. Access this article online
Website:
Quick Response Code
www.neurologyindia.com DOI: 10.4103/0028-3886.158237 PMID: xxxxx
Ophthalmic artery occlusion with total ophthalmoplegia following spinal surgery Sir, Ocular complications following a non‑ocular surgery are uncommon but may be devastating. The incidence of perioperative vision loss (POVL) after non ocular surgery ranges from 0.013% for all surgeries to upto 0.2% for spinal surgeries.[1] The causes of the sudden visual loss
Neurology India / May 2015 / Volume 63 / Issue 3
431
Copyright of Neurology India is the property of Medknow Publications & Media Pvt. Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
Copyright of Neurology India is the property of Medknow Publications & Media Pvt. Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
