To describe a case of Bickerstaff brainstem encephalitis (BBE) with hyperacute onset presenting as a stroke mimic.

BBE is a rare immunologic disease that considered to be a variant of Miller Fisher syndrome. It classically presents with subacute ophthalmoplegia, ataxia, and altered mental status, typically following an infection. Approximately two-thirds of BBE patients have anti-GQ1b antibodies positive in their serum.

Case Report & Literature Review

21-year-old woman with history of morbid obesity and migraine headaches presented as a stroke alert with hyperacute onset encephalopathy, left>right cranial nerve VI palsies, dysarthria, right hemiparesis and ataxia. NIHSS score was 10. CT head and CT Angiogram head and neck were unremarkable. She received IV Tenecteplase. MRI brain with and without contrast with thin cuts through the brain stem showed supratentorial and cerebellar leptomeningeal enhancement suggestive of meningitis but no acute infarct. Course complicated by worsening agitation in addition to persistent ophthalmoplegia and improvement in weakness. Lumbar puncture and extensive testing for infectious and chronic meningitides, and autoimmune encephalitis were notable for: CSF RBC 4, protein 378, and glucose 77. CSF WBC 239 with 92% lymphocytes and 8% monocytes. CSF meningitis panel was notable for positive CSF Lyme IgG and IgM however serum Lyme IgG and IgM, and CSF Lyme PCR were negative. GQ1-b antibodies were negative. Patient was treated with methylprednisolone 1000 mg daily for 5 doses, and 2g/kg intravenous immunoglobulin for empirical treatment of BBE. Her encephalopathy, right hemiparesis, and ataxia resolved however she had only moderate and mild improvement of her left VI and right VI nerve palsies respectively.

Bickerstaff encephalitis with hyperacute presentation is an extremely rare presentation. It is a rare but important consideration for hyperacute onset focal neurological deficits.