Ulnar Nerve Entrapment at the Cubital Tunnel Successfully Treated with Ultrasound-Guided Peripheral Nerve Hydrodissection: A Case Report and Further Evidence for a Developing Treatment Option

摘要

Ulnar nerve entrapment is the second most common peripheral nerve entrapment of the upper extremity, second only to median nerve entrapment at the carpal tunnel (1,2). The estimated annual incidence of ulnar nerve entrapment is about 0.8% per person-year (3). The ulnar nerve is composed of the C8 and Tl cervical nerve roots. As the ulnar nerve extends distally down the upper extremity, it passes deep to the Arcade of Struthers, enters the ulnar sulcus, and then courses posterior to the medial epicondyle and medial to the olecranon before entering the cubital tunnel. The cubital tunnel is defined by the arcuate ligament of Osbourne, the medial collateral ligament of the elbow, the elbow joint capsule, and the olecranon. Upon exiting the cubital tunnel, the ulnar nerve passes between the ulnar and humeral heads of the flexor carpi ulnaris and into the forearm. Entrapment may occur at several locations along the path of the nerve with the most common site being at the elbow within the cubital tunnel, known as cubital tunnel syndrome (1,2). Compression of the ulnar nerve at the sight of entrapment results in proliferation of the endoneurial and perineurial microvasculature, edema in the epineurial space, fibrotic changes, myelin sheath thinning, and axonal degeneration, if prolonged (2).