Diagnostic ultrasonography of the ulnar nerve in cubital tunnel syndrome.

Thirty-two elbows in 31 patients diagnosed as having cubital tunnel syndrome underwent ultrasonographic examination to assess morphological changes in the ulnar nerve and its surrounding tissues. On longitudinal images, the site of constriction due to the fibrous band and proximal swelling of the nerve were observed by ultrasonography and were confirmed intraoperatively. On axial images, the lengths of the major axis [7.2 (SD 1.6) mm] and the minor axis [3.7 (0.9) mm] of the nerve at the medial epicondyle were greater than those in normal subjects. There was a correlation between the stage of ulnar nerve palsy and the diameter of the major axis. Preoperatively, ganglia were detected by ultrasonography in the cubital tunnel in three cases and an anconeus epitrochlearis muscle in two.