The Fisher variant of Guillain-Barré syndrome (Fisher syndrome).

Fisher syndrome (FS) is an acute polyneuropathy typically characterized by the triad of ataxia, areflexia, and ophthalmoplegia, although it may present with 2 or even just 1 of these clinical findings. Similarities between FS and other acute polyneuropathies such as Guillain-Barré syndrome (GBS) and Bickerstaff brainstem encephalitis (BBE) suggest that FS is part of a spectrum of autoimmune disorders that may affect the peripheral and/or central nervous system. Anti-GQ1b antibody is present in the serum of more than 85% of patients with FS, but it is not specific to FS. Why some patients develop FS and others develop typical GBS or one of its other variants is still largely unknown.