Neurologic approach to drug-induced movement disorders: a study of 125 patients

Of 125 patients with neuroleptic (dopamine blocking) drug-induced movement disorders who had been referred to a specialized clinic to differentiate the predominant movement disorder, 63% had tardive dyskinesia, 30% had parkinsonism, 24% had dystonia, 7% had akathisia, and 2% had isolated tremor. Two or more movement disorders coexisted in 31 patients (25%). Functional disability was more severe in patients with akathisia than in other patients. Women outnumbered men at a ratio of 4:1, except for tardive dystonia which affected both sexes equally. The average at onset was 56 years (range, 13 to 87); 69 patients (55%) had onset of movement disorder in the sixth decade. While tardive dystonia was distributed relatively evenly in all age groups, almost a third of patients with parkinsonism had it in the eighth decade. Haloperidol was implicated in 47 patients (37%), followed by amitriptyline/perphenazine in 30%, thioridazine in 27%, and chlorpromazine in 20%. Metoclopramide-induced movement disorders were found in 10 (8%). Most patients (101 or 81%) had history of psychiatric illnesses, but of these only 44 had psychosis. Neuroleptic drugs had been prescribed for 33 patients (26%) who had gastrointestinal problems. It is important to recognize and differentiate various drug-induced movement disorders because such differentiation has pathophysiologic and therapeutic implications. Many patients could have been treated with less potent drugs.