Clinical and MRI study of brain stem and cerebellar involvement in Japanese patients with multiple sclerosis

Objectives-To investigate the clinical and MRI features of brain stem and c erebellar lesions in Japanese patients with multiple sclerosis. Methods-A retrospective study of 6 consecutive Japanese patients with multi ple sclerosis (42 women and 24 men) was done by reviewing the medical recor ds and MRI films. Forty nine patients were diagnosed as having clinically d efinite multiple sclerosis and 17 patients as having clinically probable mu ltiple sclerosis according to Poser's criteria. Prevalence rates of each br ain stem and cerebellar manifestation and frequency and distribution of MRI lesions in these patients were studied. Results-Forty three patients (65%) had one or more infratentorial manifesta tions. Cranial nerves were clinically involved in 28 patients (42%), and mo st of the lesions were identified by MRI. Among them, manifestations of fac ial, trigeminal, and abducens nerves were relatively common. Cerebellar ata xia was found in 20 patients (30%). The MRI study showed that the lesions r esponsible for ataxia in these patients were mainly found in the cerebellar peduncles, but cerebellar hemispheric lesions were detected in only four p atients (6.4%). Conclusion-The low frequency (6.4%) of the cerebellar MRI lesions in these patients is in sharp contrast with the figures reported for white patients with multiple sclerosis (50%-90%). Racial and genetic differences may have an influence on the susceptibility of each part of the CNS to demyelination in multiple sclerosis.