Impaired movement sequencing in patients with Huntington's disease: a kinematic analysis.

This experiment asked whether Huntington's disease, like Parkinson's disease, another disorder of the basal ganglia, causes a specific progressive deficit in the performance of sequential movement. Ten patients with Huntington's disease and their age-matched controls wrote the lower-case letter "l" four times in a linked cursive script, upon a graphics tablet which sampled pen position at 200 Hz. Kinematic features of sequential movement (stroke length, stroke duration, peak velocity, time to peak velocity and time from peak to zero velocity) were examined in a Group by Stroke Position (2 x 8) design, to identify which aspects of movement might show progressive disturbances. Unlike Agostino et al. [Brain 115, 1481-1495, 1992], this experiment did in fact find progressive changes in the performance of sequential movements. Kinematic analysis indicated a progressive increase in movement duration during sequential movement, that was associated with the accelerative phase of movement.