Is dorsal root entry zone lesioning effective and safe for managing continuous versus paroxysmal pains post-brachial plexus avulsion?

OBJECTIVE Patients with brachial plexus avulsion (BPA) experience chronic deafferentation pain characterized by two patterns: continuous background pain and electrical shooting paroxysmal attacks. The authors' aim was to report the effectiveness and safety of dorsal root entry zone (DREZ) lesioning in relieving the two forms of pain over short and long periods. METHODS All patients who underwent DREZ lesioning performed by the senior author for medically refractory BPA-related pain between July 1, 2016, and June 30, 2020, in Johns Hopkins Hospital were followed up. The intensity levels for continuous and paroxysmal pains were evaluated using the numeric rating scale (NRS) preoperatively and at 4 time points postsurgery, including the day of discharge, with a mean hospital stay of 5.6 ± 1.8 days; first postoperative clinic visit (33.0 ± 15.7 days); short-term follow-up (4.0 ± 1.4 months); and long-term follow-up (3.1 ± 1.3 years). The percent of pain relief according to the NRS was categorized into excellent (≥ 75%), fair (25%-74%), and poor (< 25%). RESULTS A total of 19 patients were included, with 4 (21.1%) lost to long-term follow-up. The mean age was 52.7 ± 13.6 years; 16 (84.2%) were men, and 10 (52.6%) had left-sided injuries. A motor vehicle accident was the most common etiology of BPA (n = 16, 84.2%). Preoperatively, all patients had motor deficits, and 8 (42.1%) experienced somatosensory deficits. The greatest pain relief was observed at the first postoperative and short-term follow-up visits, with the lowest proportions of patients having continuous pain (26.3% and 23.5%, respectively) and paroxysmal pain (5.3% and 5.9%, respectively). Also, the highest reductions in mean NRS scores were observed for first postoperative and short-term follow-up visits (continuous 1.1 ± 2.1 and 1.1 ± 2.3; paroxysms 0.4 ± 1.4 and 0.5 ± 1.7, respectively) compared to the preoperative symptomatology (continuous 6.7 ± 3.0; paroxysms 7.9 ± 4.3) (p < 0.001). Most patients had excellent relief of continuous pain (82.4% and 81.3%) and of paroxysms (90.9% and 90.0%) at the first postoperative visit and short-term follow-up visit, respectively. The pain relief benefits had diminished by 3 years after surgery but remained significantly better than in the preoperative assessment. At the last evaluation, the proportion of patients achieving excellent relief of paroxysmal pain (66.7%) was double that for continuous pain (35.7%) (p < 0.001). New sensory phenomena were observed among 10 patients (52.6%), and 1 patient developed a motor deficit. CONCLUSIONS DREZ lesioning is an effective and safe option for relieving BPA-associated pain, with good long-term outcomes and better benefits for paroxysmal pain than for the continuous pain component.