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

The Safety and Efficacy of Dorsal Root Entry Zone Lesioning for Pain Management in Patients With Brachial Plexus Avulsion: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

Persistent neuropathic pain after brachial plexus avulsion (BPA) is common and generally nonresponsive to medical management. Dorsal root entry zone (DREZ) lesioning is the last resort for pain management in patients with BPA. This study aims to investigate and compare the outcomes and complications of DREZ procedures.

METHODS

A systematic literature search was conducted to identify all related studies. Comparisons were based on the number of patients with preoperative pain vs postoperative pain, with the effect size calculated using the risk ratio. Mean visual analog scale (VAS) scores were extracted and analyzed between interventions. A meta-regression analysis was performed to identify risk factors for final outcomes. The rates of complications were also assessed and analyzed between interventions.

RESULTS

A total of 30 studies with 917 patients (90.0% male and 10.0% female, mean age: 42.9 ± 16.6) were included in this systematic review. Of the 917 patients who underwent surgery, 655 (71.4%) patients had significant pain reduction at the last follow-up ( P < .05). The weighted mean preoperative VAS score was 8.3 ± 1.3, compared with postoperative VAS scores (1.9 ± 2.2); a significant improvement was observed ( P < .05). The subgroup analysis showed that microsurgical DREZotomy (MDT) is associated with better outcomes in terms of VAS score improvements compared with radiofrequency (RF)-assisted DREZ lesioning ( P < .05). Meta-analysis showed that the relative risk of motor deficits was significantly lower in the MDT group, compared with the RF-assisted group ( P < .05). Meta-regression showed that older age is correlated with an elevated risk of postoperative motor deficits compared with the incidence of sensory loss.

CONCLUSION

DREZ lesioning is effective for intractable pain alleviation after BPA. Compared with RF-assisted DREZ lesioning, MDT is associated with better VAS score improvements and a lower rate of postoperative motor weakness.

Dorsal root entry zone lesioning for brachial plexus avulsion - technical evolution and long-term follow-up

BACKGROUND

Brachial plexus avulsion (BPA) injuries can cause severe deafferentation pain. This has been successfully treated with dorsal root entry zone (DREZ) lesioning. Distortions in anatomy following a BPA injury can make identifying neural structures challenging. We describe a modification to the operative technique that improves the surgical view and the advanced intraoperative neuromonitoring (IONM) employed to identify DREZ. We have analysed the long-term outcomes for pain, quality of life, and complications in patients undergoing DREZ lesioning.

METHODS

This is a single-centre retrospective case series including patients who underwent DREZ lesioning with IONM for brachial plexus avulsion between 2012 and 2022. Analysed data included pre- and postoperative pain (VAS), quality of life score for chronic pain, and complications. The evolution of the surgical approach is discussed.

RESULTS

44 consecutive patients underwent a DREZ lesioning procedure with intraoperative monitoring and mapping. In these patients the mean VAS score improved from 8.9 (7-10) to 1.87 (0-6) (p < 0.0001) at the time of discharge. 31 patients were followed-up for more than 12 months with a mean duration of follow-up of 41 months and their results were as follows: the mean VAS improved from 9.0 (7-10) to 4.1 (0-9) (p < 0.0001) at the last follow-up and the mean QOL values improved from 3.7 (2-6) to 7.4 (4-10) (p < 0.0001). The long-term outcomes were 'good' in 39%, 'fair' in 29% and 'poor' in 32% of patients. 55% of the patients were able to stop or reduce pain medications.

CONCLUSIONS

Modifications of surgical technique provide better exposure of DREZ, and IONM aids in identifying DREZ in the presence of severe intra-dural changes. Long-term outcomes of DREZ lesioning indicate not only a reduction in pain but also a significant improvement in quality of life.

Predictors of functional outcome after spinal cord surgery: Relevance of intraoperative neurophysiological monitoring combined with preoperative neurophysiological and MRI assessments

OBJECTIVES

To assess the accuracy of intraoperative neurophysiological monitoring (IONM) in predicting immediate and 3-month postoperative neurological new deficit (or deterioration) in patients benefiting from spinal cord (SC) surgery; and to identify factors associated with a higher risk of postoperative clinical worsening.

METHODS

Consecutive patients who underwent SC surgery with IONM were included. Pre and postoperative clinical (modified McCormick scale), radiological (lesion-occupying area ratio), and electrophysiological features were collected.

RESULTS

A total of 99 patients were included: 14 (14.1%) underwent extradural surgery, 50 (50.5%) intradural extramedullary surgery, and 35 (35.4%) intramedullary surgery. Cumulatively, multimodal IONM (motor and somatosensory evoked potentials, D-wave whenever possible) significantly predicted postoperative deficits (p<0.001), with a sensitivity, specificity, positive predictive value, and negative predictive value of 0.81, 0.93, 0.83, and 0.92, respectively. Sixty (60.6%) patients displayed no IONM change, whereas 39 (39.4%) displayed IONM worsening. In multivariate analysis, predictors for postoperative clinical worsening were: abnormal preoperative electrophysiological assessment (p=0.03), intramedullary tumor (p<0.001), lesion-occupying area ratio ≥0.7 (p<0.001), and IONM alterations (p<0.001). Three months after the surgical procedure, in patients presenting at least one of the risk factors described above, 45/81 (55.6%) and 19/81 (23.5%) were clinically and electrophysiologically improved, respectively; while 13/81 (16.0%) and 10/81 (12.3%) were clinically and electrophysiologically worsened.

CONCLUSION

Multimodal IONM is an essential tool to guide SC surgery, and enables the accurate prediction of postoperative neurological outcome. Specific attention should be given to patients presenting with preoperative electrophysiological abnormalities, large tumor volume, and intramedullary tumor location.

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

Following an amputation of the extremities, chronic neuropathic pain and discomfort, such as phantom limb pain (phantom pain), phantom sensation, and stump pain may occur. Clinical patterns of phantom pain, phantom sensation, and pump pain may overlap and these symptoms may also exist in one patient. Serious trauma to the upper limbs can result in brachial plexus avulsion (BPA). If BPA occurs at the same time as severe trauma of the upper extremity and the amputation of the upper limb is performed, chronic neuralgia caused by BPA may be mistaken for chronic amputation pain, such as phantom limb pain or stump pain. No major treatment advances in phantom pain have been made. However, unlike phantom limb pain, chronic neuropathic pain caused by BPA can be effectively treated with dorsal root entry zone lesioning (DREZ)-otomy. We report a patient who suffered for 34 years because the neuralgia caused by BPA was accompanied by an amputation of the arm, and so was thought to be amputation stump pain rather than BPA pain. The patient's chronic BPA pain improved with microsurgical DREZ-otomy.

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

The treatment of deafferentation pain is a primary goal of a referral center for peripheral nerve surgery. DREZ is an important asset in the neurosurgeon's armamentarium. The surgical technique and long-term results are analyzed in two series, with or without intraoperative monitoring (IOM). DREZotomy is highly effective in lumbar root avulsive injuries but is ineffective in resolving pain due to spinal cord injuries. Cervical DREZotomy for cancer pain is not superior to intrathecal morphine. In brachial plexus avulsive injuries, the largest series shows a 74% success rate, but the efficacy of the procedure is lost over time. No relevant difference has been observed since the introduction of IOM. The video can be found here: https://youtu.be/uG_kkQj5m1U.