Neuromyelitis Optica Spectrum Disorders Mimicking Wernicke's Encephalopathy: A Difficult Differential Diagnosis.

Neuromyelitis optica spectrum disorders (NMOSD) encompass a spectrum of immunomediated diseases presenting with diverse syndromes. Conversely, Wernicke's encephalopathy denotes an acute neurological condition stemming from severe thiamine (Vitamin B1) deficiency. We report a unique case of NMOSD manifesting with clinical and radiological characteristics resembling Wernicke's encephalopathy, exhibiting unresponsiveness to thiamine therapy and subsequent clinical deterioration. Our report highlights an atypical and rare presentation of NMOSD, initially confounded by changes on magnetic resonance imaging attributed to thiamine deficiency, delaying appropriate management during the early hospitalization period. While brain abnormalities are frequently documented in NMOSD, the occurrence of vertigo as an inaugural symptom is seldom reported. The patient demonstrated recovery following aggressive therapeutic interventions, including pulse steroids, plasma exchange, and rituximab therapy. Our case underscores the importance of considering NMOSD in patients displaying clinical and radiological features reminiscent of Wernicke's encephalopathy, particularly when thiamine replacement fails to elicit a response. Clinicians must recognize this unusual presentation of NMOSD promptly and initiate aggressive therapeutic measures. Early diagnosis assumes critical significance to promptly commence aggressive immunomodulatory therapy.