Long-Term Outcome of Electrodiagnostic Values and Symptom Improvement After Carpal Tunnel Release: A Retrospective Cohort Study

Purpose: The aim of this study was to evaluate electrodiagnostic studies and clinical outcomes after carpal tunnel release surgery in moderate and severe cases of carpal tunnel syndrome (CTS). Methods: Seventy-two patients with moderate or severe CTS who underwent carpal tunnel release surgery (46 unilateral; 26 bilateral; total, 98 surgeries) between 2009 and 2014 were included in the study. The cases were divided into 2 groups according to electrodiagnostic results: those with moderate CTS and those with severe CTS. Michigan Hand Outcomes Questionnaire scores and electrodiagnostic data (sensory nerve action potentials and compound muscle action potentials) were recorded before surgery and in postoperative follow-up studies obtained at 3 months, 1 year, and 5 years. Results: There were 56 surgeries in the moderate CTS group and 42 surgeries in the severe CTS group. Sensory nerve action potentials and compound muscle action potentials were significantly lower in the severe CTS group when compared to the moderate CTS group at all follow-up times. There was a significant difference in Michigan Hand Outcomes Questionnaire scores between the groups before surgery, but no significant differences at the final follow-up. It was found that the values of all parameters (sensory nerve action potentials, compound muscle action potentials, and Michigan Hand Outcomes Questionnaire score) demonstrated significant improvements with time in both the severe and the moderate CTS groups. Conclusions: Carpal tunnel release surgery improves symptoms, regardless of the preoperative severity. Postoperative electrodiagnostic study results of patients with moderate CTS improve to a greater degree than those of patients with severe CTS, but all remain abnormal. Type of study/level of evidence: Prognosis IIb. © 2022