Adduction Weakness of Fifth Finger by Neuropathy of the Ulnar Deep Motor Branch - A Case Report -

Case Report

J Korean Assoc EMG Electrodiagn Med 2016;18(2):80-84.
Published online December 31, 2016.

Received: 8 July 2016 • Revised: 24 August 2016 • Accepted: 25 August 2016

Abstract

A 38-year-old male patient presented with right little finger adduction weakness. Right little finger abduction strength was Medical Research Council (MRC) grade 5, whereas adduction was grade 1. The sensory examination did not reveal any abnormal findings. The result of peripheral motor and sensory nerve conduction studies was within normal limit with exception of right ulnar nerve motor recording at FDI. Needle electromyography revealed marked denervation in the right third palmar interosseous and first dorsal interosseous muscles. In sonography, there was a cystic mass compressing the ulnar nerve at distal carpal bone level. Eight weeks after surgical decompression, his little finger adductor power improved to MRC grade 5.

Key Words: deep motor branch of the ulnar nerve, ulnar neuropathy, ganglion cyst