Association Between Preoperative Nerve Conduction Study Severity and Outcomes After Open Carpal Tunnel Release

Background Carpal tunnel syndrome (CTS) is a common upper-extremity entrapment neuropathy for which nerve conduction studies (NCS) are widely used to confirm median neuropathy and characterize electrophysiological severity. However, the relationship between preoperative NCS severity and postoperative recovery following carpal tunnel release remains uncertain. This study evaluated the association between preoperative electrophysiological severity and six-month outcomes following open carpal tunnel release. Methods This prospective observational departmental audit included 60 consecutive adult patients with clinically and electrophysiologically confirmed CTS who underwent primary open carpal tunnel release at Kulhudhuffushi Regional Hospital, Maldives. Patients were categorized as having mild, moderate, or severe CTS according to preoperative NCS findings based on the Bland grading system. Outcomes included the Boston Carpal Tunnel Questionnaire (BCTQ), visual analogue scale (VAS) pain score, grip strength, patient satisfaction, and postoperative complications. Outcomes were assessed up to six months following surgery. Associations involving ordinal NCS severity were assessed using Spearman's rank correlation, while the relationship between distal motor latency and six-month BCTQ score was assessed using Pearson's correlation. Results The mean age of the 60 patients was 51.8 ± 10.6 years, and 42 (70.0%) were women. Sixteen patients (26.7%) had mild CTS, 28 (46.7%) had moderate CTS, and 16 (26.7%) had severe CTS. BCTQ and VAS scores improved significantly following surgery across all three severity groups. Six-month BCTQ scores differed significantly among the mild, moderate, and severe groups (1.45 ± 0.41, 1.81 ± 0.58, and 2.50 ± 0.80, respectively; F = 12.33; p < 0.001). Six-month VAS scores (F = 6.59; p = 0.003) and grip strength (F = 6.06; p = 0.004) also differed significantly among severity groups. However, the magnitude of improvement in BCTQ score did not differ significantly among the groups (p = 0.399). Longer symptom duration was associated with greater electrophysiological severity (Spearman's ρ = 0.479; p < 0.001), while greater preoperative distal motor latency was associated with a higher six-month BCTQ score (Pearson's r = 0.520; p < 0.001). Fifty patients (83.3%) were satisfied or very satisfied with their surgical outcome. Conclusions Open carpal tunnel release resulted in substantial symptomatic improvement across all preoperative electrophysiological severity groups. Greater preoperative NCS severity was associated with poorer absolute six-month patient-reported and functional outcomes, although the magnitude of symptomatic improvement was not significantly different among severity groups. Prolonged distal motor latency was moderately associated with higher residual BCTQ scores at six months. These findings suggest that preoperative NCS findings may provide useful prognostic information when counselling patients regarding expected recovery after carpal tunnel release.