Analysis of surgical treatment of chronic neuropathic pain after simple cauda equina injury

Abstract

Objective To analyze the surgical strategy, efficacy and long⁃term safety of chronic neuropathic pain (NP) after simple cauda equina injury. Methods The clinical data of patients with chronic NP after cauda equina injury treated by dorsal root entry zone (DREZ) derogation and spinal cord stimulation (SCS) in Xuanwu Hospital, Capital Medical University from September 2011 to December 2020 were analyzed. The DREZ derogation or SCS was selected according to the lesion location, injury degree and pain distribution. The long⁃term effect was evaluated according to the preoperative and postoperative Visual Analog Scales (VAS) scores, pain relief rate ≥ 50% was considered as effective, and the complications related to the surgery were followed up. Results Among 24 cases, 14 cases were treated with SCS, 9 cases had pain relief rate 60%-80%, and permanent pulse generator (IPG) was implanted; the pain relief rate was more than 60% in 2 cases, but it did not meet expectation so that the IPG was not implanted; no pain relief in 3 cases, DREZ derogation was performed later, the pain was relieved in 2 cases, and one case was still ineffective. DREZ derogation was firstly performed in 10 cases, and the pain disappeared in 7 cases; 2 cases had residual pain in some areas; one case was ineffective, and the pain was still unrelieved after SCS. After long⁃term implantation of IPG, 2 cases had been taken out of the stimulator due to fluid accumulation at the implantation site. After DREZ derogation, 3 cases had pain at the upper boundary of the preoperative pain area, which gradually disappeared within 2 weeks to one month. In one patient, the pain disappeared in early stage, which recurred after 2 years, and disappeared after the second DREZ derogation. There was no significant difference in the effective rate between 2 groups (9/13 vs. 11/15, Fisher's exact probability: P=1.000). However, DREZ derogation had high pain improvement rate than SCS [100% (0, 100%) vs. 25% (0, 75%); Z=0.441, P=0.030]. Conclusions For chronic neuropathic pain after simple cauda equina injury with clear etiology, both SCS and DREZ derogation may receive satisfactory long⁃term effect. SCS is the first choice for patients with lower limb movement, urinary and bowel function in pain area. DREZ derogation is the first choize for patients without lower limb movement, urinary and bowel. The pain improvement rate of DREZ derogation was better than that of SCS.

doi：10.3969/j.issn.1672⁃6731.2022.10.010