Bimanual co-ordination in Huntington's disease

The ability of Huntington's disease patients to co-ordinate their two hands with and without external cueing was investigated. Twelve Huntington's dis ease patients and sex- and age-matched controls performed a bimanual cranki ng task at two speeds (0.5 Hz, 1.5 Hz) and phase relationships (in-phase, a nti-phase), with and without an external metronome cue. Data were sampled a t 200 Hz, and raw displacement data for each hand, mean and standard deviat ion measures of the relative positions of the two hands and their velocitie s were then calculated. All participants could perform the in-phase movemen t, at both speeds; however, the Huntington's disease patients were more var iable and less accurate than the control participants, particularly at the fast speed. While controls could perform the anti-phase movement, in which rotation of the cranks differed by 180 degrees at both speeds, Huntington's disease patients were unable to do so at either speed, reverting to the in -phase movement at the slow speed. An external metronome cue did not improv e the performance of the Huntington's disease patients, which differentiate d this group from patients suffering from Parkinson's disease. The Huntingt on's disease patients' inability to perform the anti-phase movement may be due to damage to the basal ganglia and its output regions.