Clinical, Electrodiagnostic, and Sonographic Studies in Ulnar Neuropathy at the Elbow

The aim of this study was to determine possible correlations between the clinical characteristics, electrophysiological features, and sonographic ulnar-nerve diameter in patients with ulnar neuropathy at the elbow (UNE). We prospectively performed clinical, electrodiagnostic, and sonographic studies in 102 patients having either purely sensory signs (35%) or sensorimotor signs (65%) of UNE. Nerve conduction studies had a sensitivity of 78%, and the addition of sonography increased this to 98%. The diagnostic value of both tests was not different among cases with and without motor deficit. Motor studies with recording from the abductor digiti minimi and first dorsal interosseous muscles were equally sensitive for the detection of conduction block or velocity slowing across the elbow, but the combination yielded more positive cases than when only one study was performed. There were modest negative correlations between the electrodiagnostic parameters and the sonographic ulnar-nerve diameter. Electrodiagnostically and sonographically, there were no significant differences between clinically pure sensory and mixed sensorimotor cases of UNE, except for electrodiagnostic findings suggesting loss of motor axons in cases with motor signs. Almost half the patients with only sensory signs had electromyographic evidence of motor axonal loss. We conclude that, although UNE is clinically heterogeneous, the electrophysiological and sonographic findings are fairly consistent despite the clinical manifestations.