Somatosensory evoked potential and clinical changes after electrode implant in basal ganglia of parkinsonian patients

Abstract

Median nerve somatosensory evoked potentials (SEPs) were recorded in three parkinsonian patients who underwent electrode implant in the subthalamic nucleus and/or globus pallidus for chronic deep brain stimulation (DBS). SEPs were evoked before surgery, in a medication-free condition, and after the functional stereotactic procedure, before beginning DBS. In order to evaluate the timing of the SEP changes after the electrode implant, in three further patients SEPs were recorded within the operating theater, before and immediately after the implantation. Patients' symptoms improved immediately after the electrode implant, and both N20 and N30 amplitudes increased in the postsurgical SEP recording. The clinical and neurophysiological effects observed after surgery, before commencing DBS, can be explained by microdamage in the target nucleus following the electrode implant. They occurred also in the patients studied in the operating theater, thus suggesting that they occur immediately after the stereotactic procedure. Our results suggest that the circuitries between the basal ganglia and the primary sensorimotor cortex may be modified not only by DBS but also by microdamage due to surgery and that they exert an important influence on SEP amplitude.

Effects of DBS on auditory and somatosensory processing in Parkinson's disease

“…Existing somatosensory‐evoked potential (SEP) results have presented both an increase and decrease in early cortical deflections in amplitude by DBS [Insola et al,2005; Pierantozzi et al,1999; Priori et al,2001]. The present results display no significant difference between the DBS on/off conditions at the group level.…”

Somatosensory evoked potentials recorded from the human pedunculopontine nucleus region

“…It has been reported that decreased amplitude of the frontocentral N30 component of the median nerve SEPs in PD patients can be restored by dopaminergic medications34, 35 or after DBS electrode implantation in the internal globus pallidus or the STN without turning on the stimulation,36 likely due to a microlesion effect. We found no change in the SEP amplitudes or latencies from the PPNR after administration of dopaminergic medications, suggesting that changes in SEP associated with dopaminergic medications likely occur rostral to the PPNR.…”

Electroencephalographic read-outs of the modulation of cortical network activity by deep brain stimulation

“…In OCD patients, it was used to study the role of the associative-limbic STN on the cortical networks of motor inhibition during a stop signal task (Kibleur et al 2016). The same methodology was also used to study ERPs amplitude and latency modulation by DBS on visual evoked potentials (Jech et al 2006;Priori et al 2001), in a passive rhythmic auditory stimulation task (Gulberti et al 2015b), in a working memory task (Selzler et al 2013) and in an auditory Go/NoGo task in PD patients stimulated in the STN (Gerschlager et al 1999; and on SEPs in PD patients with STN (Priori et al 2001;Conte et al 2010;Insola et al 2005) and GPi DBS (Pierantozzi et al 1999). As for SCEPs, the reconstruction of ERP sources, for example using minimum norm (Kibleur et al 2016) or multiple sparse priors (Kibleur et al 2017), can help defining the projection of DBS modulation on cortical regions activated by the specific cognitive tasks.…”