The peripheral neuropathy in Machado-Joseph disease.

Peripheral nerve biopsies were taken from 11 patients with Machado-Joseph disease (MJD), a heredo-degenerative disease within the group of autosomal dominant ataxias. On the basis of the clinical symptoms, 2 patients were found to suffer from type I, 4 from type II and 5 from type III. All cases shared the same pathological features, which consisted of a reduction in density of myelinated and unmyelinated fibres and an increase in endoneurial collagen. It was also observed that some Schwann cells were not related to axons, whilst others showed numerous budding processes. The intensity of the changes varied considerably: it was mild in type I and II and severe in type III. Peripheral nerve changes in MJD are compared with those previously described in other forms of heredo-ataxias. It is concluded that involvement of peripheral nerves is a significant feature in this group of diseases and that peripheral nerve biopsy could be useful in the identification of the subtypes of MJD.