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.

Chronic Neuropathic Pain of Brachial Plexus Avulsion Mistaken for Amputation Stump Pain for 36 Years: A Case Report

“…Because DREZ lesioning involves ablation of the Lissaur tract and the dorsal horn within the intraparenchymal spinal cord, it inevitably carries a small but significant risk of neurological injuries, such as ataxia with tactile hypesthesia, weakness in the ipsilateral lower extremity, and genitourinary disturbances. 15 17) The dorsolateral sulcus and the underlying dorsal horn, which are surgical target for DREZ lesioning, are anatomically located between the dorsal column and the corticospinal tract. These long tracts are potentially vulnerable structures during DREZ lesioning.…”

“…These long tracts are potentially vulnerable structures during DREZ lesioning. 17 18) Therefore, intraoperative monitoring using somatosensory-evoked potentials and muscle MEPs (mMEPs) has been introduced in DREZ lesioning. 17 18) In the current case, there was no major alarming event in SSEP and mMEPs during lesioning and there were no neurologic sequelae after the operation.…”

“…After opening the pia mater of the avulsed sulcus, coagulation of grayish-yellow-colored gliotic dorsal horn was performed with fine-tipped, bipolar coagulation forceps specially designed for the application ( FIGURE 2A & B ). 15 17 18) During the coagulation, the SEP and the MEP of right lower extremity and left extremities were stable ( FIGURE 2C ).…”

Where We Come From and Are We Aware of Where We Are Going To?

“…It is currently used as a last resource for patients whose pain has not been controlled with other more conservative measures [85,87,89,90]. Other procedures like the DREZ [38,91], the zygapophyseal joint percutaneous rhizotomy [92] or the radiofrequency sacroiliac joint denervation [93] are still commonly used nowadays. Some old techniques have been improved and adapted to be minimally invasive, such as the radiofrequency thalamotomy [94,95].…”

Dorsal root entry zone lesion: nuances of the technique and long-term results

“…The long-term results are nicely illustrated through multiple graphs showing the loss of the antalgic effect with time. [8][9][10] If 75% of the patients have a good antalgic effect immediately after surgery, this score tends to fade away over the years. At a 5-year follow-up, about half of the patients originally free from pain have developed a lighter, albeit dull, aching, which is no longer a devastating experience but still leaves them not completely satisfied.…”