[A case of Machado-Joseph disease presenting pure cerebellar ataxia]

We report a 61-year-old woman with Machado-Joseph disease (MJD) presenting with pure cerebellar ataxia. The patient exhibited an unsteady gait at the age of 51 years. She was admitted to our hospital at the age of 61 years. Her older brother had been diagnosed as having spinocerebellar degeneration (SCD). Our patient showed gaze-evoked nystagmus, wide-based gait, slight lack of coordination of the four extremities, mildly ataxic speech and slight decrease in the bilateral Achilles tendon reflexes. Babinski's sign was absent. Sensory impairments were not present and muscle tone and muscle strength were normal. There was no autonomic dysfunctions. MRI revealed moderate atrophy of the cerebellum and pons. We performed gene analysis of SCD using white blood cells from the patient, and the analysis showed 70 CAG repeats in the MJD1 gene, which is an abnormally high number of repeats. Compared with three reported cases of MJD presenting pure cerebellar ataxia, only our patient showed a nasal voice. The number of CAG repeats in the MJD1 gene of our patients was the most prolonged of the four cases. MJD should be considered in patients with familial SCD even if their neurological signs and symptoms outside the cerebellum are not obvious.