Cubital tunnel syndrome: diagnosis and management.

tunnel syndrome, the second most common compression neuropathy of the upper extremity. Patients often present with pain, paresthesias and/or weakness that if left untreated may lead to significant disability. This article reviews the etiology, diagnosis and management of cubital tunnel syndrome. The ulnar nerve originates from branches of the C8 and T1 spinal nerve roots and is the terminal branch of the me-dial cord of the brachial plexus. In the arm, the ulnar nerve courses between the medial head of the triceps and the brachialis muscles. It then travels posterior to the medial epicondyle of the humerus and enters the cubital tunnel. The roof of the cubital tunnel consists of Osborne's ligament, which spans from the medial epicondyle of the humerus to the olecranon of the ulna, and the floor consists of the medial collateral ligament and joint capsule of the elbow. After exiting the cubital tunnel, the ulnar nerve passes between the humeral and ul-nar heads of the flexor carpi ulnaris muscle and enters the anterior compartment of the forearm. In the forearm, it courses between, and innervates, the flexor carpi ulnaris and ulnar half (i.e., fourth and fifth fingers) of the flexor digitorum profundus muscles. The ulnar nerve then divides into superficial and deep branches. The deep branch innervates the hypothenar, third and fourth lumbrical, interosseous, ad-ductor pollicis and deep head of the flexor pollicis brevis muscle, and the superficial branch provides sensory function for the medial hand. Ulnar nerve compression most commonly occurs at the elbow. At the elbow, the ulnar nerve can be compressed at five sites: the arcade of Struthers, medial intermuscular septum, medial epicondyle, cubital tunnel and deep flexor pronator aponeurosis. 1 (Figure 1) Ulnar nerve compression within the cubital tunnel, known as cubital tunnel syndrome, is the most common site of compression. During elbow flexion, the ulnar nerve is stretched 4.5 to 8 mm (since it lies posterior to the axis of motion of the elbow) and the cubital tunnel cross-sectional area narrows by up to 55% as intraneural pressures increase up to 20-fold. 2, 3 As a result, repeated and sustained elbow flexion can irritate the ulnar nerve and eventually lead to cubital tunnel syndrome. This relationship between prolonged elbow flexion and cubital tunnel syndrome has been reported in patients who habitually sleep in the fetal position or sleep in the prone position with their hands tucked under the pillow. More recently, …