MEDIAN NERVE SOMATOSENSORY-EVOKED POTENTIALS - APOMORPHINE-INDUCED TRANSIENT POTENTIATION OF FRONTAL COMPONENTS IN PARKINSONS-DISEASE AND IN PARKINSONISM

Somatosensory evoked potentials (SEPs) to median nerve stimulation hav e been recorded from parietal and frontal districts in 43 parkinsonian s, 17 patients with parkinsonism and 35 healthy controls matched for a ge and sex. Latency/amplitude characteristics of the parietal P14-N20- P25 and of the frontal P20-N30-P40 wave complexes before and after (10 , 20, 30 and 60 min) subcutaneous administration of apomorphine chlori de were evaluated in all the 60 patients and in 3 controls. The fronta l waves N30 and P40 were either absent or significantly smaller than n ormal in 31 patients with Parkinson's disease (PD) (72.1%) and in 9 wi th parkinsonism in baseline records (56.3%). Following apomorphine, th e parietal deflections did not significantly vary in amplitude. On the contrary, the frontal complex showed a significant amplitude increase in 27 PD and 8 parkinsonisms (respectively 62.8 and 47.1%); 79.1% of PD and 35.3% of parkinsonisms were improved clinically. Amplitude incr ease was evident at 10 min after apomorphine, in parallel with clinica l improvement, and vanished nearly in coincidence with the end of the clinical effect.