High-frequency oscillations in human posterior tibial somatosensory evokedpotentials are enhanced in patients with Parkinson's disease and multiple system atrophy

High-frequency oscillations (HFOs) and the underlying P37 primary somatosen sory response evoked by posterior tibial nerve stimulation were recorded in patients with Parkinson's disease (PD) and in those with multiple system a trophy (MSA), as well as in normal controls, in order to increase the signa l-to-noise ratio, we averaged a large number of responses (9998 epochs) wit h a high sampling rate (20 kHz per channel). HFOs were extracted by filteri ng the wide band-pass recording of the P37 potential with a 600-900 Hz band -pass filter. High-amplitude HFOs were observed in both the PD and MSA pati ents. Furthermore, the duration of illness was positively correlated with t he amplitude of HFOs. The results suggest that HFOs are enhanced by dysfunc tion of the basal ganglia. (C) 2001 Elsevier Science ireland Ltd. All right s reserved.