Journal of Neuro-Ophthalmology, September 2015, Volume 35, Issue 3

Nerve Fiber Layer Infarcts in Thiamine Deficiency

Thiamine deficiency classically manifests as the triad of Wernicke encephalopathy: acute confusional state, ataxic gait, and ocular motor dysfunction. However, most patients do no present with this classic triad. Optic neuropathy in thiamine deficiency is a rare manifestation and is usually associated with fundus appearances of optic disc swelling or optic disc pallor. We present 2 unique cases of thiamine deficiency where the fundus demonstrated peripapillary retinal nerve fiber layer thickening without florid disc swelling or pallor.

Nerve Fiber Layer Infarcts in Thiamine Deficiency Paul I. Sia, MBChB, David I. T. Sia, MBChB, John L. Crompton, FRANZCO, FRACO, Robert J. Casson, PhD, FRANZCO Abstract: Thiamine deficiency classically manifests as the triad of Wernicke encephalopathy: acute confusional state, ataxic gait, and ocular motor dysfunction. However, most patients do no present with this classic triad. Optic neuropathy in thiamine deficiency is a rare manifestation and is usually associated with fundus appearances of optic disc swelling or optic disc pallor. We present 2 unique cases of thiamine deficiency where the fundus demon-strated peripapillary retinal nerve fiber layer thickening without florid disc swelling or pallor. Journal of Neuro-Ophthalmology 2015;35:274-276 doi: 10.1097/WNO.0000000000000243 © 2015 by North American Neuro-Ophthalmology Society CASE 1 A56-year-old woman reported 1 week of progressive visual loss in both eyes, preceded by 6 weeks of poor diet secondary to oral discomfort after dental extraction. She had a history of long-standing alcohol consumption of 10.7 standard drinks daily and tobacco use of 20 cigarettes a day. Examination revealed that she was malnourished with a body mass index of 15 kg/m2. Visual acuity was counting fingers in each eye, pupillary reflexes were sluggish with light-near dis-sociation, and horizontal gaze-evoked nystagmus was present. Extraocular movements were full. Fundus examination re-vealed bilateral superior and inferior retinal nerve fiber layer (RNFL) thickening with a flame-shaped hemorrhage infe-rior to the left macula. There was no disc swelling or pallor (Fig. 1A). Optical coherence tomography confirmed the presence of bilateral superior and inferior RNFL thickening (Fig. 2). Automated perimetry (Humphrey 30-2) showed generalized depression in the right visual field (mean devia-tion [MD] 228.25 dB) and a central scotoma in the left FIG. 1. A. Case 1. There is superior and inferior retinal nerve fiber layer thickening with a hemorrhage (arrow) below the left macula. B. Case 2. Thickening of the retinal nerve fiber layer is present along the superotemporal and inferotemporal vascular arcades with a splinter hemorrhage (arrow) in the right fundus. Department of Ophthalmology & Visual Sciences, South Australian Institute of Ophthalmology, Royal Adelaide Hospital, Adelaide, Australia. The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper. Address correspondence to Paul I. Sia, MBChB, South Australian Institute of Ophthalmology, Royal Adelaide Hospital, North Terrace, Adelaide 5000, South Australia, Australia; E-mail: [e-mail] 274 Sia et al: J Neuro-Ophthalmol 2015; 35: 274-276 Photo Essay Section Editor: Timothy J. McCulley, MD Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. field (MD 216.94 dB). Brain magnetic resonance imaging was unremarkable, but laboratory investigations confirmed low thiamine level of 38 nmol/L (normal: 70-200 nmol/L). She was treated with thiamine and multivitamin supplemen-tation and she made a dramatic visual recovery, with the acuity improving within days to 20/15 in both eyes. CASE 2 A 20-year-old woman with a history of chronic alcoholism (30 standard drinks per day) presented with severe confusion and altered consciousness. She had full ocular motility with vertical and horizontal gaze-evoked nystagmus. Fundus FIG. 2. Case 1. Optical coherence tomography confirms superior and inferior retinal nerve fiber layer thickening. Sia et al: J Neuro-Ophthalmol 2015; 35: 274-276 275 Photo Essay Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. examination revealed bilateral RNFL thickening superior and inferior to the disc (Fig. 1B). Further examination was pre-cluded by her severe confusion. Computed tomographic imaging of the brain was unremarkable. She was managed with hydration, correction of electrolyte imbalances, as well as thiamine and multivitamin replacements. Her fundus find-ings resolved. However, she was diagnosed with Wernecke- Korsakoff syndrome and suffered ongoing cognitive impair-ment and short-term memory loss. Thiamine (vitamin B1) is a water-soluble vitamin that plays a major role as a coenzyme in carbohydrate metab-olism in the central nervous system. Thiamine deficiency classically manifests as the triad of Wernicke encephalopa-thy: acute confusional state, ataxic gait, and ocular motor dysfunction. Visual loss is uncommon in thiamine defi-ciency and is usually bilateral, severe, and associated with optic disc swelling (1). Optic neuropathy is a rare manifestation of thiamine deficiency. Peripapillary RNFL thickening associated with thiamine deficiency, as in our patients, has been reported previously in cases of protracted vomiting and bariatric surgery (1, 2). The slowly progressive optic neuropathy seen in chronic alcoholism more commonly produces a clinical picture of pallor of the optic discs (2-4). The fundus findings seen in our cases bear a resemblance to those seen in methanol-induced optic neuropathy and in Leber hereditary optic neuropathy, in which mitochondrial dysfunction underlie the pathogenesis. It is postulated that mitochon-drial dysfunction, as a result of thiamine deficiency, first gives rise to swelling and hemorrhage of the RNFL and subsequent optic disc swelling appears only if mitochon-drial damage is severe and prolonged (2-4). Our 2 cases demonstrate a unique manifestation of thiamine deficiency: peripapillary RNFL infarcts in the absence of florid disc swelling or pallor. Furthermore, the first case is notable in that severe visual loss with peripapillary RNFL thickening and retinal hemorrhage was the only manifestation of her thiamine deficiency. Recognition of these ophthalmoscopic findings in thia-mine deficiency is important to avoid unnecessary testing, which may delay urgent treatment with thiamine supplementation. STATEMENT OF AUTHORSHIP Category 1: a. Conception and design: R. Casson, J. Crompton, D. I. T. Sia, and P. I. Sia; b. Acquisition of data: J. Crompton, D. I. T. Sia; c. Analysis and interpretation of data: J. Crompton, and D. I. T. Sia. Category 2: a. Drafting the manuscript: P. I. Sia. b. Revising it for intellectual content: R. Casson, J. Crompton, and D. I. T. Sia. Category 3: a. Final approval of the completed manuscript: R. Casson and J. Crompton. REFERENCES 1. Gratton SM, Lam BL. Visual loss and optic nerve head swelling in thiamine deficiency without prolonged dietary deficiency. Clin Ophthalmol. 2014;8:1021-1024. 2. Bohnsack BL, Patel SS. Peripapillary nerve fiber layer thickening, telangiectasia, and retinal hemorrhages in Wernicke encephalopathy. J Neuroophthalmol. 2010;30:54-58. 3. Li JM, Rucker JC. Irreversible optic neuropathy in Wernicke encephalopathy and Leber hereditary optic neuropathy. J Neuroophthalmol. 2010;30:49-53. 4. Surges R, Beck S, Niesen WD, Weiller C, Rijntjes M. Sudden bilateral blindness in Wernicke encephalopathy: case report and review of the literature. J Neurol Sci. 2007;260:261-264. 276 Sia et al: J Neuro-Ophthalmol 2015; 35: 274-276 Photo Essay Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited.