Anti-GQ1b IgG antibody is associated with ataxia as well as ophthalmoplegia

Close association between the increase in anti-GQ1b immunoglobulin G (IgG) antibody;and ophthalmoplegia in Miller Fisher syndrome (MFS) and Guillain-B arre syndrome (GBS) has been reported. We investigated whether anti-GQ1b Ig G antibody also is associated with ataxia, another of the MFS triad. Of 149 patients who had anti-GQ1b IgG antibody without profound weakness, 144 sho wed ophthalmoplegia (120 showed both ophthalmoplegia and ataxia; 24, ophtha lmoplegia without ataxia). In contrast, five showed ataxia without ophthalm oplegia. Some large neurons of the dorsal root ganglia were immunostained w ith anti-GQ1b monoclonal antibody. Anti-GQ1b IgG antibody may thus be assoc iated with ataxia as well as ophthalmoplegia. Ataxia may be due to its bind ing to a subset of primary sensory neurons. (C) 1999 John Wiley & Sons, Inc .