Mechanisms of ataxia.

Ataxia, or incoordination of movement, is a disorder that can be caused by damage to several different nervous system structures. Common causes of ataxia include damage of the cerebellum and damage of sensory structures. Sensory ataxia is distinguishable from cerebellar ataxia, because the sensory ataxia causes symptoms to worsen when movements are made with the eyes closed. The basic mechanism underlying ataxia is not yet understood, although studies indicate that ataxia may be due in part to an inability to coordinate the relative activity of multiple muscles and adjust movements at a given joint for the effects of other moving joints (interaction torques). Based on these findings, it could be reasoned that treatments focusing on strategies to reduce the complexity of a movement by minimizing the number of moving joints or by stabilizing against the inertial effects of limb movement will improve function. 2,12-14,21-23 Further testing of treatments for ataxia, however, is needed. Ataxia may be best treated by teaching people to avoid rapid multijoint movements and instead make slower movements limited to single joints.