Clinical and genetic evaluation of Japanese autosomal dominant cerebellar ataxias; is Machado-Joseph disease common in the Japanese?

of the neuropathy. After three months the diplopia had disappeared. The CSF showed 6 x 10'/l mononuclear cells and a protein content of 0-88 g/l; some oligoclonal bands were present, but the IgG index was normal. Brain MRI showed multiple abnormalities of periventricular white matter. Some of these enhanced after intravenous administration of gadolineum, suggesting active CNS inflammation. In the pons an area of high T2 signal intensity was seen in the proximal part of the fila radicularia of the left abducens nerve, providing substantial evidence for a sixth nerve palsy of CNS origin (figure). Although a vascular origin cannot be fully excluded, the distribution of the lesions was typical for plaques seen in multiple sclerosis. Moreover, the enhancing white matter lesions were present several weeks after onset of the sixth nerve palsy, making a coincidental vascular lesion unlikely. Lesions without enhancement may reflect older lesions. Nevertheless, multiple sclerosis could not be diagnosed, as other white matter abnormalities in the CNS were asymptomatic. Previous studies have suggested that cranial nerve lesions in CIDP may be related to CNS lesions.'" However, MRI abnormalities were not more common in patients with cranial nerve involvement than in those without.' The enhancing pontine lesion in our patient is suggestive of active CNS demyelination and therefore probably responsible for a central origin of the ocular palsy, which interestingly occurred independent of peripheral nerve involvement at that time. Previous information on white matter abnormalities in the CNS in this patient was not obtained as MRI is not a routine diagnostic procedure in CIDP. Yet these abnormalities may occur in a disproportionate number of patients. ' I 6 7