Amantadine sulfate infusion effect on N30 somatosensory evoked potentials in Parkinson's disease

The purpose of this study was to evaluate the effect of amantadine sulfate infusion on the N30 component of the median nerve short-latency somatosensory evoked potentials (SSEPs) in patients with Parkinson's disease (PD). Twenty patients with advanced PD and severe motor fluctuations received a 6-day course of amantadine sulfate infusion (400 mg/day) plus their usual levodopa medication. Patients were assessed clinically by means of the Unified Parkinson's Disease Rating Scale (UPDRS-III and -IV). SSEPs to median nerve stimulation were recorded from the parietal and frontal regions before and after the 6-day course of amantadine infusion. Mean UPDRS motor score during the ON and OFF phase improved after amantadine infusion, as did motor fluctuations. SSEP changes resulting from amantadine sulfate treatment were observed in the P20-N30 amplitude as follows: Mean P20-N30 amplitudes before and after treatment were 2.15 +/- 1.11 microV and 3.06 +/- 1.19 microV respectively (p = 0.000), whereas mean N30-P40 amplitude increased from 2.7 +/- 1.6 microV to 3.9 +/- 1.3 microV after treatment (p = 0.000). Our results indicate that coincident to its clinical impact, amantadine infusion in patients with PD affects electrophysiologic parameters as well.