Impact of subthalamic deep brain stimulation on auditory information processing in patients with advanced Parkinson´s disease

Bilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN) clearly improves dopamine-dependent motor deficits in patients with Parkinson’s disease (PD). While there is evidence for dopaminergic sensitivity of central sensory processing, the effects of DBS on sensory information processing are less clear. We therefore investigated the effects of STN-DBS on auditory information processing, using auditory evoked potentials (AEP). To this end, we compared amplitude, latency and habituation of AEPs in 12 patients with advanced PD to those of age-matched controls. The stimulus paradigm consisted of rhythmic metronome-like clicks presented at different inter-stimulus intervals (ISI). High-density EEG-recordings were carried out prior to and 3-12 months following surgery for STN-DBS in the practically defined OFF-state. We studied the effects of STN-DBS at different stimulation frequencies (5, 20 and 130 Hz). Prior to surgery, PD patients showed significantly larger AEP amplitudes (P50, N1 and P2) in central and frontal areas compared to controls. Moreover, compared to controls N1 and P2- latencies were increased and AEP habituation reduced in PD patients. Electrode implantation per se as well as STN-DBS had a normalizing effect on AEPs. The stimulation effect was found to be frequency-specific. High-frequency STN-DBS led to a normalization of P2, but not P50 and N1 amplitudes. Under both theta-and beta-frequency STN-DBS, however, amplitude and latency of all three AEP components were affected. Our findings support and expand previous reports of dysregulated central auditory processing in PD as expressed by AEPs. The present results suggest that STN-DBS differentially affects the auditory evoked responses and may thus also influence sensorimotor processing at higher order sensory levels.