Finger tremor and extrapyramidal side effects of neuroleptic drugs.

Finger tremor and extrapyramidal side-effects (EPSEs) were measured in seven patients before and during neuroleptic drug treatment to assess the relationship between the onset of EPSEs and changes in finger tremor spectra. Tremor and EPSEs were also measured in twelve patients stabilized on neuroleptic drugs to determine whether tremor could provide a reliable index of the presence and severity of extrapyramidal system disturbance. A downward shift in peak tremor frequently was noted within 48 hours of starting neuroleptic drug therapy, usually before the onset of EPSEs, and a significant negative relationship between the severity of EPSEs and tremor frequency (but not tremor amplitude). The peak frequency of finger tremor is thus a sensitive index of extrapyramidal disturbance and might be of value in predicting which patients taking neuroleptic drugs need anti-parkinsonian therapy.