Optic neuritis and palatal dysarthria as presenting features of post-infectious GQ1b antibody syndrome

A 31-year-old man had optic neuritis 2 weeks after a diarrheal illness, followed by several deficits including palatal dysarthria, diplopia, ataxia, sensory dysfunction, and mild dysautonomia. Brain MRI and CSF were normal. Nerve conduction studies were initially normal and subsequently showed mild reduction in sensory amplitudes. Anti-GQ1b IgG titer was positive. Deficits resolved after treatment with IVIg. This clinical constellation represents an overlap between Miller Fisher syndrome (MFS) and the pharyngeal-cervical-brachial (PCB) variant of Guillain-Barre syndrome (GBS), along with the infrequently reported central feature of optic neuritis. Campylobacter jejuni enteritis may have triggered the syndrome by molecular mimicry. GQ1b antibodies are associated with MFS, GBS, Bickerstaff brainstem encephalitis and PCB; they form an overlapping spectrum of features, hence the anti-GQ1b syndrome.