Association between the elbow flexion test and extraneural pressure inside the cubital tunnel.

PURPOSE: The elbow flexion test is a standard, provocative diagnostic test for cubital tunnel syndrome (CubTS). The purpose of this study was to investigate the association between the elbow flexion test and the degree of extraneural pressure in the cubital tunnel of CubTS patients. METHODS: Extraneural pressure on the ulnar nerve in the cubital tunnel was evaluated using 0.7-mm thickness catheter during surgery of 25 CubTS cases and compared with the results of preoperative elbow flexion testing. Statistic analysis was performed using Student's t-test with a confidence level of 95% (p < .05). RESULTS: Forty-eight percent of the patients were positive for the elbow flexion test. Mean extraneural pressure was significantly higher in maximum elbow flexion than in maximum elbow extension (p < .001). No significant association was seen between the result of 45 seconds of the elbow flexion test and the extraneural pressure in the cubital tunnel induced by maximum elbow flexion (p = .45). CONCLUSIONS: Our results suggested that the mechanism of provocation of symptoms of CubTS by the elbow flexion could not be explained simply by dynamic pressure in the cubital tunnel, and other pathophysiological factors could also be contributing. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic III.