Normative values for short-segment nerve conduction studies and ultrasonography of the ulnar nerve at the elbow.

Abstract

In patients with ulnar neuropathy at the elbow (UNE), short-segment nerve conduction studies (NCS) are rarely performed due to unclear reference values. We excluded controls with subclinical UNE, calculated normative values, and tested them in UNE patients. Clinical examination, ultrasonography (US), and 2-cm short-segment ulnar motor NCS across the elbow were performed in 49 controls and 67 UNE patients. In controls, subclinical UNE was diagnosed if at least 2 studies were outside the reference limits in the same 2-cm segment. Exclusion of controls with subclinical UNE produced less stringent normative values (2-cm conduction velocity: 25 to 31 m/s; US cross-sectional area: 11.6 to 9.6 mm2), which raised diagnostic sensitivity (short-segment NCS: 76% to 90%; 10-cm NCS: 72% to 85%, US: 43% to 79%). We propose the use of our normative values in patients with clinically definite and probable UNE after exclusion of alternative diagnoses.