A case of Fisher syndrome presented by rapidly progressing bilateral palatoplegia after cytomegalovirus infection

A 35-year-old male developed sensory abnormality of peripheral limbs and oral cavity after prior infection with diarrhea and cold symptoms. Hyperrhinolalia, nasopharyngeal reflux, double vision, and wobbling in walking rapidly progressed. Neurological examination revealed palatoplegia, omnidirectional ophthalmoplegia, hyperreflexia, sensory disturbance of extremities, and truncal and limb ataxia due to decreased deep sensation. A peripheral nerve conduction study found a slight decrease in sensory nerve action potential of the median nerve and a decrease in F wave frequency of the median nerve. Serum IgM-CMV antibody was positive on admission. After IVIg therapy, palatoplegia and ataxia markedly improved. In this case, GalNAc-GD1a and GM2 antibodies, which are often detected after CMV infection, were positive in addition to the GT1a and GQ1b antibodies, and it was assumed that these findings were associated with the palatoplegia, which is included in cranial nerve palsy. Pathophysiologically, the present case is considered to be an overlap with acute oropharyngeal palsy (AOP), which is a rare subtype of Guillain-Barre syndrome, and Fisher syndrome (FS). The clinical aspects of the present case suggest a continuous spectrum between AOP and FS.