Fisher syndrome

Abstract

Fisher syndrome (FS) is a regional variant of Guillain-Barré syndrome (GBS) characterized by acute ophthalmoplegia, ataxia, and areflexia. It has a male predominant sex difference with a M: F ratio of ~2: 1, and 70% of FS patients have episodes of antecedent respiratory infection. The annual incidence varies geographically and is higher in Far East countries. As a variant of GBS, immunotherapies are sometimes applied to FS, but the efficacies and benefits of these treatments have not been established. The most important diagnostic marker is serum IgG antiganglioside GQ1b antibody, which is present in 80-95% of FS patients. Using this antibody as a nosological marker has revealed a presumed relationship between FS and other conditions, including Bickerstaff brainstem encephalitis. Anti-GQ1b antibody may be actively involved in the pathogenic process of FS. The localization of the GQ1b epitope in the human ocular motor nerves, muscle spindle, and dorsal root ganglia could reasonably explain all of the core clinical features and physiological observations of this disease. GQ1b-mimic oligosaccharide structures have been identified in bacterial lipooligosaccharides, and immunization with these lipooligosaccharides produces anti-GQ1b antibodies. Siglec-7, a sialic acid-binding Ig-like lectin expressed on monocytes and macrophages, strongly binds to GQ1b and may be involved in antigen-presentation and the induction of anti-GQ1b antibody.