Ultrasonographic Findings of the Ulnar Nerve Following Elbow Flexion in Patients with Cubital Tunnel Syndrome

Objective To evaluate the ultrasonographic findings obtained following various degrees of elbow flexion in patients with cubital tunnel syndrome (CuTS). Design Retrospective, cross-sectional study. Setting General teaching hospital, rehabilitation unit. Subjects Electrophysiological and ultrasonographic assessments were performed on 11 elbows of healthy controls and 21 elbows of 17 patients with CuTS. Methods Dynamic movement of the ulnar nerve during elbow motion was measured. To measure ulnar nerve dynamic movement during elbow motion, the distance from the medial epicondyle (ME) to the nearest surface of the ulnar nerve toward the ME was measured at the cubital tunnel inlet at elbow extension (0°), elbow flexion to 60°, and elbow flexion to 90°. Results The distance between the ME and ulnar nerve was lower in CuTS patients than in healthy patients at all elbow flexion angles. This difference was statistically significant at 0° and 60° elbow flexion (P < 0.05). When calculating the cutoff value, the distance between the ME and ulnar nerve at full elbow extension for CuTS diagnosis was 0.53 cm (sensitivity = 71.4%, specificity = 90.7%). The distance ratio between the ME and ulnar nerve for diagnosis of ulnar neuropathy at the elbow was 24.4% (sensitivity = 76.2%, specificity = 100%). Conclusion Measurement of the distance between the ME and ulnar nerve in full elbow extension may facilitate the diagnosis of patients with CuTS. These findings may be important for CuTS diagnosis, as they were also observed in patients with mild-stage CuTS.