Electrodiagnostic severity does not predict short- to midterm outcomes of cubital tunnel release surgery

Hypothesis: This study aimed to explore the prognostic value of electrodiagnostic studies (EDS) to clarify their utility in clinical practice prior to cubital tunnel release surgery and to identify patient factors associated with patient-reported functional improvement after surgery. Our hypothesis was that patients with severe preoperative findings on EDS will tend to experience less functional improvement after surgery given the extent of ulnar nerve compressive injury. Methods: Patients with cubital tunnel syndrome and preoperative electrodiagnostic data treated from 2012 to 2022 with cubital tunnel release were assessed regarding demographic information, preoperative physical examination findings, EDS findings, postoperative complications, and patient-reported outcomes. Short- to midterm quick Disabilities of the Arm, Shoulder, and Hand questionnaire (qDASH) scores were collected for all patients for further evaluation of preoperative EDS data. Patients were grouped into those who had met the minimal clinically important difference (MCID) in delta qDASH at short- to midterm follow-up and those who did not. EDS data included sensory nerve onset latency, peak latency, amplitude, conduction velocity, as well as motor nerve latency, velocity, and amplitude. Electromyographic (EMG) studies were also reviewed, which included data pertaining to fibrillations, presence of abnormal fasciculation, positive sharp waves, variation in insertional activity, motor unit activity, duration of activity, and presence of increasing polymorphisms. Results: Of the 257 patients included, 160 (62.0%) were found to meet the MCID for short- to midterm qDASH scores. There were no significant differences between patients who did or did not meet the MCID regarding baseline demographics, comorbidities, preoperative examination findings, and operative technique. Patients who met MCID tended to have lower complication (3.80% vs. 7.20%, P = .248) and revision (0.60% vs. 4.10%, P = .069) rates, but these findings were not statistically significant. The cubital tunnel severity as determined by the EDS was similar between cohorts (14.1% vs. 14.3%, P = .498). Analysis of EMG testing showed there were no significant differences in preoperative, short- to midterm qDASH, or delta short- to midterm qDASH scores for patients with or without abnormal EMG findings. Multivariate regression suggested that only age (P = .003) was associated with larger delta qDASH scores. Conclusion: Patient-reported preoperative disease severity may predict the expected postoperative change in ulnar nerve functional improvement, and EDS may not have prognostic value for patients undergoing cubital tunnel decompression. Therefore, physicians may suggest surgical treatment without positive EDS findings and still expect postoperative improvement in functional outcomes.