[Movement-related cortical potentials (MRCPs) and voluntary movement--clinical usefulness of MRCPs].

The gradient of negative slope (Ns') changed in parallel with the velocity of step movement in normal individuals. We can not evaluate the MRCPs without considering this factor among patients and/or subjects. We recorded the MRCPs of thirty nine patients with cerebellar ataxias and sixteen patients with Parkinson disease (PD). Goniometer was attached on the patient's wrist to measure the velocity of the wrist movement. In the patients with spinocerebellar degeneration with denate nucleus lesion (Machado-Joseph disease, DRPLA, MERRF, dyssynergia cerebellaris myoclonica, galactosialidosis), the gradients of Ns' were reduced, although the movements themselves were as fast as normal control. In the patients with spinocerebellar degeneration without this lesion, the MRCPs were able to record as normal control, and their gradients of Ns' became steeper according to the increase of the movement angular velocity. On the contrary, in the patients with Parkinson disease, the gradients of Ns' were steeper in the patients with slow movement than in those with fast movement. The MRCP helps us to investigate the pathophysiology of the movement disorders. It is desirable that physiological data on the MRCP are extensively accumulated.