Wernicke's Encephalopathy in a Young Non-alcoholic Woman Secondary to Prolonged Reduced Oral Intake: A Case Report.

Wernicke's encephalopathy (WE) is an acute neurological disorder resulting from thiamine deficiency and is classically associated with chronic alcohol misuse. However, it may also occur in non-alcoholic patients with prolonged malnutrition, persistent vomiting, or impaired nutritional intake, making diagnosis particularly challenging when the classical triad of ophthalmoplegia, ataxia, and altered mental status is incomplete or develops gradually. Delayed recognition can result in irreversible neurological injury, whereas early treatment with thiamine is associated with promising outcomes. We report the case of a 26-year-old woman who presented with persistent vomiting, significant weight loss, and poor oral intake. During her admission, she developed acute binocular diplopia, bilateral ophthalmoplegia, gait ataxia, confusion, and short-term memory impairment. She fulfilled all four Caine criteria for WE, demonstrating dietary deficiency, oculomotor abnormalities, cerebellar dysfunction, and altered mental state/memory impairment. Initial neuroimaging raised concern for pituitary pathology; however, subsequent endocrine investigations and vascular imaging excluded pituitary apoplexy and adrenal insufficiency. Nerve conduction studies and cerebrospinal fluid analysis were unremarkable, excluding peripheral demyelinating disease. Given the characteristic clinical presentation in the setting of prolonged nutritional deficiency, a diagnosis of WE was made, and treatment with intravenous thiamine (Pabrinex) was initiated. The patient demonstrated rapid neurological improvement, with resolution of confusion, marked recovery of ocular signs and ataxia, and improvement in Montreal Cognitive Assessment score from 16/30 to 28/30 before discharge. This case highlights the importance of maintaining a high index of suspicion for WE in non-alcoholic patients presenting with prolonged vomiting and malnutrition. It also emphasises the utility of the Caine criteria in supporting the diagnosis when the classical triad is not initially apparent. Although initial neuroimaging raised concerns regarding pituitary pathology, subsequent investigations excluded alternative diagnoses, reinforcing that imaging findings should not distract from the clinical diagnosis of WE. Prompt empirical thiamine replacement remains essential to prevent permanent neurological damage and achieve excellent clinical recovery.