The nerve-first paradigm: Preoperative EMG severity as a prognostic marker of clinically meaningful recovery after adult spinal deformity surgery.

PurposeTo determine whether preoperative EMG severity predicts clinically meaningful recovery after adult spinal deformity surgery.MethodsIn this single-center observational cohort, prospectively collected data from 84 patients undergoing adult spinal deformity surgery were retrospectively analyzed. EMG radiculopathy severity was graded 1-3; grade 3 defined severe abnormality. 24-month ODI and VAS-leg improvement, MCID achievement, satisfaction, complications, and reoperations were compared. Regression models adjusted for baseline score, age, and fused levels.ResultsODI improved by 16.20 points and VAS-leg by 3.38 points overall; however, only 51.2% achieved ODI MCID. Severe EMG patients had less ODI improvement (9.09 vs 17.62 points; difference, 8.53; 95% CI, 4.23-12.84) and less VAS-leg improvement (1.15 vs 3.82 points; difference, 2.67; 95% CI, 1.83-3.52). Increasing EMG severity independently predicted less improvement and higher ODI MCID failure.ConclusionMajor adult spinal deformity surgery improved average patient-reported outcomes; however, severe preoperative EMG abnormality identified a distinct high-risk, low-benefit phenotype in whom surgery was less likely to produce clinically meaningful radicular pain relief and more likely to be followed by poor satisfaction, complications, and reoperation.