A blinded study of the suppressibility of involuntary movements in Huntington's chorea, tardive dyskinesia, and L-dopa-induced chorea

Videotapes of patients with Huntington's chorea, tardive dyskinesia (TD), and L-DOPA-induced chorea in Parkinson's disease were taken while the patients were seated with their legs dangling. The videotapes were scored in a blinded fashion for suppressibility of dyskinesias. Most patients with TD or L-DOPA-induced chorea substantially suppressed their involuntary movements, whereas most patients with Huntington's chorea did not. There was a small overlap between the TD and Huntington's chorea groups and suppressibility therefore could not absolutely distinguish between them. Suppressibility testing may nonetheless be a valuable clinical tool since a good, excellent, or complete suppressibility rating was highly suggestive of TD but not Huntington's chorea. TD and L-DOPA-induced chorea may be more pathophysiologically similar to each other than either is to Huntington's chorea.