Cubital Tunnel Syndrome
Cubital tunnel syndrome is an uncommon cause of lateral forearm pain and weakness that can be quite distressing to the patient. This entrapment neuropathy manifests as pain and associated paresthesias in the lateral forearm that radiate to the wrist and ring and little fingers. The symptoms are often aggravated by prolonged flexion of the elbow. The pain of cubital tunnel syndrome has been characterized as unpleasant and dysesthetic. The onset of symptoms is usually after repetitive elbow motions or from repeated pressure on the elbow, such as using the elbows to arise from bed.
Direct trauma to the ulnar nerve as it enters the cubital tunnel may result in a similar clinical presentation. Untreated, progressive motor deficit and ultimately flexion contracture of the affected fingers can result. Cubital tunnel syndrome is most often caused by compression of the ulnar nerve by an aponeurotic band that runs from the medial epicondyle of the humerus to the medial border of the olecranon.
What are the Symptoms of Cubital Tunnel Syndrome
Physical findings include tenderness over the ulnar nerve at the elbow. A positive Tinel sign over the ulnar nerve as it passes beneath the aponeuroses is usually present.
Weakness of the intrinsic muscles of the forearm and hand that are innervated by the ulnar nerve may be identified with careful manual muscle testing, although early in the course of the evolution of cubital tunnel syndrome, the only physical finding other than tenderness over the nerve may be the loss of sensation on the ulnar side of the little finger.
As the syndrome progresses, the affected hand may take on a claw-like appearance. A positive Wartenberg sign indicative of weakness of the adduction of the fifth digit is often present. A positive scratch collapse test is often present.
How is Cubital Tunnel Syndrome diagnosed?
Electromyography helps distinguish cervical radiculopathy and cubital tunnel syndrome from golfer’s elbow.
Plain radiographs are indicated in all patients with cubital tunnel syndrome to rule out occult bony pathological processes, such as osteophytes impinging on the ulnar nerve. Based on the patient’s clinical presentation, additional tests, including complete blood cell count, uric acid level, erythrocyte sedimentation rate, and antinuclear antibody testing, may be indicated.
Magnetic resonance imaging (MRI) of the elbow is indicated if joint instability is suspected and to identify the cause of ulnar nerve entrapment. Ultrasound evaluation is also useful if the diagnosis is in question. Injection of the ulnar nerve serves as a diagnostic maneuver and a therapeutic maneuver.
Cubital tunnel syndrome is often misdiagnosed as golfer’s elbow, which accounts for the many patients with “golfer’s elbow” who fail to respond to conservative measures. Cubital tunnel syndrome can be distinguished from golfer’s elbow, because in cubital tunnel syndrome, the maximal tenderness to palpation is over the ulnar nerve 1 inch below the medial epicondyle, whereas with golfer’s elbow, the maximal tenderness to palpation is directly over the medial epicondyle.
Cubital tunnel syndrome also should be differentiated from cervical radiculopathy involving the C7 or C8 roots and golfer’s elbow. Cervical radiculopathy and ulnar nerve entrapment may coexist as the “double crush” syndrome. The double crush syndrome is seen most commonly with median nerve entrapment at the wrist or carpal tunnel syndrome.
Initial treatment of the pain and functional disability associated with cubital tunnel syndrome should include a combination of nonsteroidal anti inflammatory drugs (NSAIDs) or cyclooxygenase-2 (COX-2) inhibitors and physical therapy. Local application of heat and cold also may be beneficial.
The repetitive movements that incite the syndrome should be avoided. For patients who do not respond to these treatment modalities, injection of the ulnar nerve at the elbow with a local anesthetic and steroid may be a reasonable next step. If the symptoms of cubital tunnel syndrome persist, surgical exploration and decompression of the ulnar nerve are indicated.
The major complications associated with cubital tunnel syndrome fall into two categories: (1) iatrogenically induced complications resulting from persistent and overaggressive treatment of “resistant golfer’s elbow” and (2) the potential for permanent neurological deficits as a result of prolonged untreated entrapment of the ulnar nerve. Failure of the clinician to recognize an acute inflammatory or infectious arthritis of the elbow may result in permanent damage to the joint and chronic pain and functional disability.
Cubital tunnel syndrome is a distinct clinical entity that is often misdiagnosed as golfer’s elbow, which accounts for the many patients with “golfer’s elbow” who fail to respond to conservative measures. Cubital tunnel syndrome can be distinguished from golfer’s elbow because in cubital tunnel syndrome, the maximal tenderness to palpation is over the ulnar nerve and a positive Tinel sign is present, whereas with golfer’s elbow, the maximal tenderness to palpation is over the medial epicondyle. If cubital tunnel syndrome is suspected, injection of the radial nerve at the elbow with a local anesthetic and steroid gives almost instantaneous relief. Careful neurological examination to identify preexisting neurological deficits that may later be attributed to the nerve block should be performed on all patients before beginning ulnar nerve block at the elbow.