Objective: This study aims to clarify the role of the STN, previously suggested as an integrative component in the control of the basal ganglia-thalamocortical circuit, on higher sensory processing as reflected on amplitude, latency and phase reversal characteristics of long-latency (LL) SSEPs.

Background: A possible approach for addressing sensory function of the subthalamic nucleus (STN) pertain somatosensory evoked potentials (SSEPs) elicited by median nerve stimulation (MNS). SSEPs have been mainly described at the scalp and the cortical level by electroencephalographic, magnetoencephalographic and intracranial cortical recordings, and at the subcortical level by previous deep brain stimulation (DBS) electrode studies focusing on early sensory processing and short-latency SSEPs (latency<40 ms).

Methods: Postoperative recordings were performed on twelve Parkinson’s disease (PD) patients that underwent DBS treatment. SSEPs from the STN were elicited by median nerve stimulation (MNS) to the wrist of PD patients. Ipsi- and contra-lateral MNS were applied with a 3 s inter-stimulus interval.

Results: We describe (LL)-SSEPs in the STN. Four distinctive LL-SSEP waves (“LL –complex” consisting of P80, N100, P140 and N200 component) were recognized by using both monopolar and bipolar referencing and both ipsi- and contra-lateral MNS. Long-latency SSEPs exhibited high amplitude, reproducibility and were already visible after only one MNS repetition. Phase reversal and/or maximum amplitude gave evidence for their local origin within the STN.

Conclusions: The occurrence of LL-SSEPs in the STN of PD patients underscores a role of this structure in higher sensory processing, while emphasizing a sensorimotor integrative role of the STN on the regulation of the basal ganglia thalamocortical circuit.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/long-latency-somatosensory-evoked-potentials-of-the-subthalamic-nucleus/