Proposal for electrodiagnostic evaluation of patients with suspected ulnar neuropathy at the elbow.

Abstract

To develop an evidence-based electrodiagnostic (EDx) approach to patients with suspected ulnar neuropathy at the elbow (UNE). We prospectively recruited patients with suspected UNE, took a history and performed clinical neurologic, EDx and ultrasonographic (US) examinations. Ulnar motor and mixed nerve 5 × 2 cm, 2 × 4 cm and 10 cm studies across the elbow were compared regarding sensitivity and precise localization of UNE. In 175 evaluated patients, the highest sensitivity/precise localization was demonstrated by the motor 5 × 2 cm study (93%/92%), followed by the 2 × 4 cm study (89%/83%) and the 10-cm study (82%/0%). The sensitivities of mixed ulnar nerve studies to diagnose/precisely localize UNE were 12-23%/27-36% lower than the corresponding motor studies. Based on our data, we suggest starting EDx evaluation of UNE with a motor 2 × 4 cm study (recording from either the abductor digiti minimi or the first dorsal interosseous muscles), with two additional stimulation sites being added if the initial result is negative. This results in a motor 4 × 2 cm study. In all suspected UNE patients, an antidromic sensory study to the 5th finger should also be performed. The proposed EDx protocol is robust, sensitive and time efficient. We hope that it will improve the diagnosis of UNE.