Treatment of Anconeus Epitrochlearis- Induced Cubital Tunnel Syndrome With Ultrasound-Guided Hydrodissection

BACKGROUND: Cubital tunnel syndrome is the second most common cause of peripheral nerve entrapment in the upper extremity, trailing only carpal tunnel neuropathy. While the roof of the cubital tunnel is most often formed by Osborne’s ligament, the anomalous, evolutionary remnant muscle, the anconeus epitrochlearis, has been previously identified as a potential cause of cubital tunnel syndrome. CASE REPORT: A 45-year-old female physical education coach noted bilateral upper extremity pain, numbness, paresthesias, and early onset exercise fatigue originating at the medial elbow and radiating down the ulnar nerve distribution. Sonographic evaluation showed evidence of a hypertrophic anconeus epitrochlearis in the right upper extremity causing compression of an enlarged, bifid ulnar nerve. The patient was treated with 3 separate ultrasound-guided hydrodissection injections, which resulted in complete resolution of her symptoms and a decrease in the ulnar nerve cross-sectional area on sonographic evaluation at 24-week follow-up. CONCLUSION: A hypertrophic anconeus epitrochlearis can cause cubital tunnel syndrome and ultrasound-guided hydrodissection is a potentially efficacious surgery-sparing treatment option. KEY WORDS: Cubital tunnel syndrome, hydrodissection, ulnar neuralgia, ultrasound