Coarse, jerky foot tremor: tremographic investigation of an objective sign of acute akathisia.

In a previous clinical investigation, jerky foot movements were observed in patients with akathisia. Tremographic techniques were employed in the present study to characterise this motor activity. Six psychiatric patients with signs and symptoms of akathisia, six control patients matched for antipsychotic drug dose, and five drug-free normal subjects, were selected and assessed for evidence of drug-induced movement disorders. The two patient groups proved to be closely matched on clinical and demographic variables. An accelerometer was used to record finger and toe tremor in all subjects according to a standard procedure. Analysis of the amplitude, frequency and wave-form data collected revealed that the akathisia patients were characterised by the presence of large amplitude, low frequency (less than 4 Hz), rhythmic foot movements. Changes in the severity of akathisia at follow-up were reflected in changes in the amplitude and frequency of this dyskinesia. Possible clinical and pathophysiological implications of the findings are presented.