SEPS N30 AMPLITUDE IN PARKINSONS-DISEASE AND IN PHARMACOLOGICALLY INDUCED RIGIDITY - RELATIONSHIP WITH THE CLINICAL STATUS

The frontal N30 wave amplitude of somatosensory evoked potentials (SEP s) has been studied in 41 Parkinson's disease (PD) patients (pts) in a basal condition and compared to that of 30 normal subjects; moreover the N30 amplitude and clinical motor score have been evaluated in a su bgroup of 30 PD pts before and during apomorphine infusion and in a se cond subgroup of 22 PD pts also during levodopa chronic therapy. The d ata show that N30 amplitude is decreased in PD pts in basal condition and increased following both treatments by a percentage proportional t o the clinical improvement, Analysis by non parametric correlations sh owed that the increase is well correlated to the clinical score amelio ration induced by apomorphine in the more affected side. The best corr elation was to rigidity score amelioration in the group of PD pts in m edium stage (Hohen and Yahr stage between 2 and 3), suggesting a relat ionship between the rigidity and N30 amplitude decrease. Non parkinson ian subjects, treated with low (11 aged normal subjects) and high (eig ht young psychotic pts) doses of antidopaminergic drugs, were studied. N30 amplitude decreases were only found in the group of eight psychot ic pts showing clinical extrapyramidal signs, produced by the high dos e of drug administered, but not in the group treated with the lower do se not producing extrapyramidal side effects, although this dose was e fficacious on different modalities of evoked potentials. We conclude t hat N30 amplitude decrease in PD reflects the dopaminergic lack parall eled by clinical symptoms. We propose that N30 amplitude variations by dopaminergic agonists may be useful in the clinical evaluation of dop amine related and non related tone alterations.