Miller Fisher Syndrome and Bickerstaff Encephalitis as Manifestations of an Anti-gq1b Antibody Syndrome: Case Report

Abstract Miller Fisher syndrome (MFS) and Bickerstaff brainstem encephalitis (BBE) represent two clinical entities within the anti-GQ1b antibody spectrum, both characterized by acute onset and immune-mediated pathophysiology. We report the case of a 22-year-old woman who presented with dorsal pain, visual disturbances, ophthalmoplegia, and ataxia, showing a progressive neurological decline. Neuroimaging and cerebrospinal fluid analyses revealed no structural or cytochemical abnormalities. Despite this, the patient tested positive for anti-GQ1b antibodies, confirming the diagnosis of an atypical Miller Fisher syndrome associated with brainstem involvement. Early initiation of intravenous immunoglobulin and corticosteroid therapy led to a rapid and almost complete recovery of neurological function. This case highlights the diagnostic challenges of anti-GQ1b antibody syndromes, emphasizing the need for high clinical suspicion and early immunotherapy to prevent irreversible neurological damage.