Ulnar Motor Nerve Conduction Study for Lesion Localization in Ulnar Neuropathy at Elbow

Original Article

J Korean Assoc EMG Electrodiagn Med 2012;14(2):66-70.
Published online December 1, 2012.

Received: 13 August 2012 • Revised: 9 November 2012 • Accepted: 9 November 2012

Abstract

Objectives: To compare abductor digiti minimi (ADM) recording with first dorsal interosseous (FDI) recording for the localization of ulnar neuropathy at the elbow (UNE) with electrodiagnostic study and inching test. Methods: Eighty-seven hands with UNE were collected. Compound muscle action potentials were recorded from both ADM and FDI muscles and ulnar nerve was stimulated at the wrist, 3 cm distal and 7 cm proximal to the medial epicondyle. One cm short segment study of ulnar nerve was performed from 4 cm distal to 3 cm proximal to the medial epicondyle by inching test. Results: UNE was diagnosed in 83 out of 87 hands with ADM recording and 84 out of 87 hands with FDI recording. Seven hands had nonconcordant abnormal findings along the recording site. In the inching test, 12 hands were not localized and 12 hands was localized with only one muscle recording. 48 hands showed same localization and 15 hands showed different localization with both ADM and FDI recordings. Conclusion: Since the result can differ according to the location of the recording electrode, motor conduction study and inching test of ulnar nerve should include recording from both ADM and FDI muscles.

Key Words: Ulnar nerve, Inching test, Abductor digiti minimi muscle, First dorsal interosseous muscle