Positive Ultrasonographic Findings Of Cubital Tunnel Syndrome Is Highly Predictive Of Symptomatic Improvement Following Cubital Tunnel Release

PURPOSE: The gold-standard test for cubital tunnel syndrome (CuTS) is electrodiagnostics, which can be painful and has a low sensitivity in early compression. Nerve ultrasound is predictive of symptomatic recovery following carpal tunnel release, even when electrodiagnostics are negative. It is not known whether this finding is applicable to CuTS. Case series suggest that ultrasound may be more sensitive than electrodiagnostics during early CuTS. We hypothesize that preoperative nerve cross-sectional area (CSA) >9mm2, indicating CuTS, is predictive of successful CuTR in patients with negative electrodiagnostics. METHODS: This is a single-center retrospective study of all patients who underwent CuTR between 1/1/2019 and 12/31/2022. We compared outcomes for patients who underwent CuTR with negative electrodiagnostics/positive ultrasound to patients with positive electrodiagnostics/no ultrasound. Primary outcomes included subjective improvement in symptoms, as well as QuickDASH, PROMIS scores, and Visual Analog Scale (VAS) scores. RESULTS: 948 patients underwent CuTR, 8.8% of patients underwent nerve ultrasound, and 91% of patients underwent electrodiagnostics. Average CSA at the medial epicondyle was 14.82mm2. 82% of patients with positive electrodiagnostics/no ultrasound experienced improvement of symptoms following CuTR, compared with 88% of patients with negative electrodiagnostics/positive ultrasound. QuickDASH and VAS scores for both groups were improved from preoperative baseline at 1 year follow-up without a significant difference between groups. CONCLUSION: Nerve ultrasound demonstrating CuTS is highly predictive of recovery after CuTR as measured by subjective improvement, QuickDASH and VAS scores, even with negative electrodiagnostics. Nerve ultrasound is a viable diagnostic tool to identify CuTS with high specificity.