ANALYSIS OF SINGLE-JOINT RAPID MOVEMENTS IN PATIENTS WITH SPORADIC OLIVOPONTOCEREBELLAR ATROPHY

Patients with pure cerebellar cortical atrophy (CCA) present isolated cerebellar signs, whereas patients with sporadic olivopontocerebellar atrophy (sOPCA) present various combinations of cerebellar and extrace rebellar signs. However, the differential diagnosis between these two forms of cerebellar degeneration is often a challenge for the clinicia n. Therefore, any test helping in this differential diagnosis might ha ve a potential clinical interest. In this study, our goal was to inves tigate the adaptation to increased inertia in patients with sOPCA exhi biting combined cerebellar and pyramidal signs, during the performance of fast wrist flexions. We found that these patients exhibited a hype rmetria which remained unchanged after addition of inertia, because th ey were unable to increase neither their agonist activity (launching f orce), nor their antagonist activity (braking force). This contrasts w ith our previous findings in patients with CCA. In these latter, the h ypermetria worsened when the inertial load of the hand increased becau se those patients were able to increase their agonist activity, but no t their antagonist activity. The adaptation to inertia might thus help to differentiate CCA and sOPCA. (C) 1997 Elsevier Science B.V.