To describe a case of concomitant Bickerstaff encephalitis (BBE) and Wernicke encephalopathy (WE), and highlight its diagnostic challenges.

The approach to encephalopathy is usually characterized by multimodal investigation, including laboratory testing, neuroimaging, EEG, and analysis of the cerebrospinal fluid (CSF). Clinicians are typically satisfied when an abnormality in the ancillary testing is found, and a diagnosis is reached. Complex presentations should raise suspicion for mixed disorders, especially when the neurological symptomatology does not fully align with a unified diagnosis. 

A 22-year-old female developed progressive confusion and unintentional weight loss of a month duration. Her mental status abruptly precipitated one week before admission. Neurologically, she exhibited somnolence, confusion, vertical nystagmus, dysarthria, truncal ataxia, and areflexia. Nutritional deficiency was suspected, and vitamin panel was sent. She was started on empirical intravenous thiamine supplement. Brain MRI showed abnormality in the dorsomedial thalami. CSF analysis was remarkable for isolated hyperproteinorrhacia (71mg/dL). Laboratory testing demonstrated positive GQ1b-antibodies. She received intravenous immunoglobulin and three-days of intravenous methylprednisolone. Vitamin B1 level returned low at 35nmol/L. Under treatment, her encephalopathy, ataxia, and areflexia resolved. She was discharged home with residual mild nystagmus, on a tapering dose of prednisone and oral thiamine. 

The constellation of symptomatology did not align with a unified single diagnosis. The presence of confusion, nystagmus, and ataxia, pointed toward WE, which was confirmed by laboratory testing. However, the altered sensorium, dysarthria, and areflexia hinted to an additional pathological process. The positivity of GQ1b-Ab, along with the MRI abnormality, satisfied the diagnostic criteria for BBE. 

To our knowledge, the co-occurrence of WE and BBE has not heretofore been described. Mixed encephalopathy must be considered in atypical neurological presentation. Investigation should be thorough and multimodal treatment promptly started. Failure to recognize mixed encephalopathies could lead to unnecessary escalation of treatment for an erroneously presumed refractory disease