Painful Myoclonus Triggered by Lateral Antebrachial Cutaneous Nerve Entrapment at the Brachioradialis Muscle

Compression of the lateral antebrachial cutaneous nerve is a rare clinical entrapment syndrome often overlooked as an initial etiology of pain. We present a case of an episodic upper limb painful movement disorder (myoclonus) in a 16-yr-old adolescent girl with a remote history of a surgically stabilized supracondylar humeral fracture who was later found to have entrapment of the lateral antebrachial cutaneous nerve. The incidence of a painful myoclonus triggered by a peripheral nerve entrapment is unknown. Combining a history and physical examination, electromyography, nerve conduction studies, and ultrasound enabled us to make an accurate diagnosis that was confirmed by resolution of symptoms after surgical release. This study conforms to all CARE guidelines and reports the required information accordingly (see Supplemental Check list, Supplemental Digital Content 1, http://links.lww.com/PHM/A855).