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

Abstract

Objective: To develop an evidence-based electrodiagnostic (EDx) approach to patients with suspected ulnar neuropathy at the elbow (UNE).

Methods: 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.

Results: 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.

Conclusions: 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.

Significance: The proposed EDx protocol is robust, sensitive and time efficient. We hope that it will improve the diagnosis of UNE.

Keywords: Electrodiagnostic protocol; Electromyography; Short-segment nerve conduction studies; Ulnar neuropathy at the elbow.