Objective:

To discuss diagnostic challenges in Bickerstaff encephalitis by describing a case from our institution 

Background:

Bickerstaff brainstem encephalitis (BBE) is a rare autoimmune disorder characterized by ophthalmoplegia, ataxia, and altered consciousness, associated with anti-GQ1b antibodies. It often occurs after an infection and is associated with good outcomes. However, diagnosis can be challenging given overlapping features with other causes of rhombencephalitis.  Our case highlights the pitfalls in reaching an etiologic diagnosis. 

Design/Methods:

NA 

Results:

A 63-year-old woman was admitted for perforated sigmoid diverticulitis with pneumoperitoneum. On day three of hospitalization, she developed acute encephalopathy, diplopia, headache, and bilateral upper extremity ataxia. MRI of the head revealed bilateral T2/FLAIR hyperintensities and contrast enhancement within the brainstem and middle cerebellar peduncles, concerning for rhombencephalitis. Cerebrospinal fluid (CSF) analysis showed WBC -17 μL, RBC 3 μL, protein 38 mg/dL, and glucose 58 mg/dL. She was empirically treated with broad-spectrum antibiotics and intravenous immunoglobulin. Listeria PCR in CSF resulted negative. Autoimmune and paraneoplastic encephalitis panels were unremarkable. Antibodies to GQ1B were detected at a titer of 1:400, confirming BBE.

Conclusions:

The etiological diagnosis of brainstem encephalitis can be challenging. Careful consideration of the clinical spectrum is crucial to differentiate between infective, autoimmune, and paraneoplastic causes. Listerial rhombencephalitis, which was our initial working diagnosis, is the most common cause of infectious rhombencephalitis. However, patients are typically immunocompetent, with up to 80% of patients reporting no previous medical illness. Most patients have a fever > 38°C at onset, and brainstem involvement is strikingly asymmetric. The classic triad of bilateral ophthalmoplegia, ataxia, and encephalitis, as seen in this case, is highly suggestive of BBE. Anti-GQ1b seropositivity has been reported in about 68% of cases in large studies. Our case highlights key differences between important infectious causes of rhombencephalitis and the eventual diagnosis of BBE.