Use of ultrasonography in ulnar nerve entrapment surgery--a prospective study.

The purpose of our study is to assess the usefulness of high-resolution ultrasonography in observing the morphology and dynamics of the ulnar nerve in the cubital tunnel and also the efficacy of ultrasonography in a more accurate diagnosis and appropriate surgical treatment decision. Cross-sectional area of the ulnar nerves of 40 healthy volunteers in the control group were measured bilaterally at the level of the epicondyle, 2 cm proximal to and 2 cm distal to the epicondyle. Measurements were obtained for elbows both in extension and flexion. Then, we prospectively obtained the cross-sectional area values of 18 patients at the same levels, elbows in extension and flexion position, and compared the data obtained from the patient group and the control group. The differences between the cross-sectional areas of the ulnar nerves in extension and flexion were statistically significant in the patient population (p < 0.001). Mean cross-sectional area of the ulnar nerve in the patient population was calculated as 0.16 cm(2), and we accepted the cut-off point as 0.1 cm(2). This value for cross-sectional area yielded a sensitivity of 90% and a specificity of 100% in diagnosis of ulnar nerve entrapment. Results substantiated conspicuous morphological changes in ulnar nerve during flexion and extension of the elbow. We also observed that as the degree of the nerve displacement by virtue of elbow flexion that is discerned by ultrasonography increased, a more aggressive decompressive surgery was needed for an appropriate treatment.