Intraoperative Neurophysiological Monitoring (Motor and Somatosensory Evoked Potentials) in Dorsal Root Entry Zone Lesioning for Brachial Plexus Avulsion Pain

Abstract

Aims: To address the feasibility and importance of intraoperative neurophysiological monitoring (IONM) in dorsal root entry zone (DREZ) lesioning for brachial plexus avulsion pain. Methods: Muscle motor evoked potential (mMEP) and somatosensory evoked potential (SSEP) were applied during DREZ lesioning for brachial plexus avulsion pain. Results: IONM of mMEPs and SSEPs was feasible for monitoring of the spinal cord during DREZ lesioning. With the exception of 3 unrecordable mMEPs in ipsilateral arms, mMEPs were preserved and referenced to look for changes according to lesioning in 6 upper extremities (66.6%) and 8 lower extremities. All 3 patients with >50% reduction in baseline mMEP amplitude after lesioning in either the ipsilateral upper or lower extremities showed postoperative ataxia and weakness of the lower extremities (100%). Only 2 out of 9 patients (22.2%) with brachial plexus avulsion pain had discernible baseline SSEPs in the ipsilateral upper extremities. One of 2 patients with discernible SSEPs in the upper extremities showed significant SSEP events during the DREZ lesioning and experienced postoperative ataxia and weakness in the legs despite the absence of a SSEP event in the lower extremities. Conclusion: Significant events on IONM were common during DREZ lesioning for brachial plexus avulsion pain and were closely related to the occurrence of postoperative neurological deficits.