Effect of Deep Versus Moderate Neuromuscular Block on Chronic Postsurgical Pain After Lumbar Spine Surgery: A Randomized Clinical Trial.

BACKGROUND

Chronic postsurgical pain (CPSP) is a debilitating complication following posterior lumbar surgery, often exacerbated by retraction-induced paraspinal muscle injury. While deep neuromuscular blockade (DNMB) optimizes surgical conditions, its ability to mitigate this mechanical injury and prevent pain chronification remains unproven. This trial investigated the effect of DNMB on the incidence of CPSP and its underlying biological mechanisms.

METHODS

Participants scheduled for posterior lumbar interbody fusion were randomized to either the DNMB group or the moderate neuromuscular blockade (MNMB) group. The primary outcome was CPSP incidence at 3 months. Secondary outcomes included the incidence of CPSP at 6 months, postoperative opioid consumption, acute muscle injury biomarkers (creatine kinase [CK], myoglobin [MYO], and lactate dehydrogenase [LDH]), and radiographic assessment of cross-sectional area (CSA) and fat infiltration (FI) of paraspinal muscles.

RESULTS

Of 180 patients randomized, 178 were included in the modified intention-to-treat analysis. At 3 months, the incidence of CPSP was significantly lower in the DNMB group (17/89 [19.1%]) compared with the MNMB group (31/89 [34.8%]) (risk ratio [RR], 0.6; 95% confidence interval [CI], 0.3-0.9; P = .018). There was no significant difference in the incidence of CPSP at 6 months (13/89 [14.6%] vs 17/89 [19.1%]; RR, 0.8; 95% CI, 0.4-1.5; P = .423). Furthermore, the DNMB group demonstrated lower postoperative pain scores, reduced opioid consumption, and higher surgeons' satisfaction scores (P < .05, P < .001, P < .001, respectively). This group also exhibited lower early postoperative serum concentrations of CK, MYO, and LDH (all P < .001 on postoperative day 1), alongside better preservation of CSA and less progression of FI on 6-month magnetic resonance imaging (MRI; all P < .001).

CONCLUSIONS

Compared to MNMB, DNMB significantly reduced the 3-month incidence of CPSP and decreased opioid consumption in patients undergoing spinal surgery. These clinical benefits were associated with reduced acute muscle injury, as reflected by lower early injury biomarkers and better preservation of long-term paraspinal muscle structure.