Background: Wernicke's encephalopathy is a serious medical condition associated with high morbidity and mortality caused by deficiency of thiamine. This disease is classically associated with alcoholism, but is underappreciated in the nonalcoholic population. There is growing acknowledgement of the development of Wernicke's encephalopathy in patients with malignancies.

Methods: We conducted a literature review in PubMed for cases of Wernicke's encephalopathy occurring in patients with malignancy. We also present the case of a 47-year-old woman with recurrent laryngeal cancer and multiple hospital admissions for malnutrition. Neurological examination was notable for pendular nystagmus, severe gait ataxia, confusion, and poor memory consolidation. MRI of the brain was significant for T2-weighted fluid-attenuated inversion recovery hyperintensities in periaqueductal regions, medial thalami, and the tectal plate, typical for Wernicke's encephalopathy. She was treated with thiamine repletion, and had marked improvement in her mental status and some improvement in her vision problems and ataxia, although some nystagmus and significant short-term memory impairment persisted.

Results: The literature review yielded dozens of case reports of Wernicke's encephalopathy in patients with malignancy, dominated by cases of patients with malignancies of the gastrointestinal system, followed by those with hematologic malignancies.

Conclusions: Malignancy is an important risk factor for the development of Wernicke's encephalopathy. This diagnosis is underappreciated and difficult for the clinician to discern from multifactorial delirium. Clinicians should be aware to treat at-risk patients with thiamine immediately, especially if multiple risk factors are present.