POSTEXCITATORY INHIBITION AFTER TRANSCRANIAL MAGNETIC STIMULATION OF THE MOTOR CORTEX IN PATIENTS WITH DRUG-INDUCED PARKINSONISM AND IN HEALTHY-INDIVIDUALS

The duration of the postexcitatory inhibition after transcranial magne tic stimulation was investigated in 16 patients with drug-induced park insonism and in 20 healthy control individuals. In the patients, the c hlorpromazine-equivalent of the neuroleptic medication was determined, and the severity of the drug-induced parkinsonism was measured using the Simpson-Angus Scale score. Group comparison (U-test) revealed a si gnificant shorter postexcitatory inhibition in patients than in contro l individuals. Regression analyses showed a negative correlation betwe en the Simpson-Angus scale score and the duration of the postexcitator y inhibition. The correlation only reached significance for a group of patients who received at least one butyrophenone derivate. No clear-c ut relation was found between the chlorpromazine equivalent and the po stexcitatory inhibition. These results indicate that drug-induced park insonism shares features of genuine Parkinson's disease. Furthermore, it seems possible to assess the extrapyramidal side effect of butyroph enone derivates, but not for other neuroleptic drugs, by means of the method described. (C) 1998 Rapid Science Ltd.