Anti-GQ1b IgG antibody syndrome: clinical and immunological range.

OBJECTIVES To clarify the nosological relation among Miller Fisher syndrome (MFS), Guillain-Barré syndrome (GBS) with ophthalmoplegia, Bickerstaff's brain stem encephalitis (BBE), and acute ophthalmoparesis without ataxia. Serum samples from patients with each condition often have anti-GQ1b IgG antibody. METHODS Information on antecedent illness, initial symptoms, neurological signs during the illness, and CSF findings were reviewed in 194 patients with anti-GQ1b IgG. It was determined whether overlapping MFS and GBS (MFS/GBS), as well as overlapping BBE and GBS (BBE/GBS), is explained by the combined action of anti-GQ1b IgG and anti-GM1 or anti-GD1a IgG, serological markers of GBS. RESULTS Based on the diagnostic criteria, all the patients with acute ophthalmoparesis, MFS, MFS/GBS, BBE/GBS, and BBE had external ophthalmoplegia; all the patients with MFS, MFS/GBS, or GBS had hyporeflexia or areflexia; and all those with MFS and BBE showed ataxia. Tendon reflexes were decreased or absent in 91% of those with BBE/GBS, 67% of those with BBE, and 53% of those with acute ophthalmoparesis. Ataxia was present in 68% of the patients with MFS/GBS and 45% of those with BBE/GBS. Antecedent illness caused by upper respiratory tract infection had occurred in 60% to 80% of these patients, and CSF albuminocytological dissociation in 25% to 75%. Anti-GM1 or anti-GD1a IgG was present in 50% of those with GBS, 35% of those with MFS/GBS, 27% of those with BBE/GBS, 16% of those with MFS, and 8% of those with BBE. CONCLUSIONS These findings together with the common autoantibody (anti-GQ1b IgG) suggest that a common autoimmune mechanism functions in the pathogenesis of these illnesses. In a larger study, it was confirmed clinically that MFS, GBS, BBE, and acute ophthalmoparesis are closely related, forming a continuous range. This is supported by the immunological findings. The term "anti-GQ1b IgG antibody syndrome" is not intended to be used as a clinical diagnosis, but recognition of this syndrome is useful for understanding the aetiological relation among the various illnesses and for introducing the established treatments of GBS for use with other conditions.