Ulnar neuropathy with normal electrodiagnosis and abnormal nerve ultrasound.

Ulnar neuropathy at the elbow (UNE) is the second most common entrapment neuropathy. It is diagnosed with electrodiagnostic studies, but they can yield false-negative results. Ultrasound was used to examine 4 patients with UNE and negative electrodiagnostic findings, and it showed ulnar nerve enlargement near the elbow in all cases, with a mean cross-sectional area of 20.1 mm. This indicates that ultrasound may be a useful tool for assessing those with UNE symptoms and normal electrodiagnostic findings.