Diagnosis of Ulnar Nerve Entrapment at the Arcade of Struthers with Electromyography and Ultrasound

Ulnar neuropathy is caused by compression of the ulnar nerve in the upper extremity, frequently occurring at the level of the elbow or wrist. Rarely, ulnar nerve entrapment may be seen proximal to the elbow. This report details a case of ulnar neuropathy diagnosed and localized to the arcade of Struthers with electromyography (EMG) and ultrasound (US) imaging and confirmed at time of operative release. US imaging and EMG findings were used to preoperatively localize the level of compression in a patient presenting with left ulnar neuropathy. In this case, ulnar entrapment 8 cm proximal to the medial epicondyle was diagnosed. Surgical release was performed and verified the level of entrapment at the arcade of Struthers in the upper arm. Alleviation of symptoms was noted at 8-week follow-up; no complications occurred. US imaging can be used in complement with EMG studies to properly diagnose and localize the level of ulnar nerve entrapment. This facilitates full release of the nerve and may prevent the need for revision surgery.