Cubital Tunnel Syndrome

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Clinically Relevant Anatomy

Cubital tunnel syndrome is an irritation or injury of the ulnar nerve in the cubital tunnel at the elbow.  The ulnar nerve is comprised of nerve roots C8 and T1. The ulnar nerve can become compressed withiin the cubital tunnel at multiple levels including: the arcade of Struthers, the medial intermuscular septum, the medial epicondyle, Osborn's ligament at the cubital tunnel and the flexor-pronator aponeurosis.

Mechanism of Injury / Pathological Process

Cubital tunnel syndrome may be a result of direct or indirect trauma and is bulnerable to traction, friction, and compression. Traction injuries may be the result of longstanding valgus deformity and flexion contractures, but are most common in throwers due to extreme valgus stress placed on the arm.  Compression of the nerve at the cubital tunnel may occur due to reactive changes at the MCL, adhesions within the tunnel, hypertrophy of the surrounding musculature, or joint changes.

Clinical Presentation

Early in the disorder, primary complaint is typically medial elbow pain. Numbness and tingling may also be present in the 4th and 5th digits. The patient may also report non-painful "snapping" or "popping" during active and passive flexion and extension of the elbow.  A Wartenberg sign (abduction of the fifth digit due to weakness of the third palmar interosseous muscle) may be present. Active and passive ROM may not be decreased. The ulnar nerve may be enlarged or palpable and tender in the groove.

Diagnostic Procedures

The Elbow Flexion Test: Typically performed bilaterally with the shoulder in full external rotation and te elbow actively held in maximal flexion with wrist extension for 1 minute. A positive test is reproduction of numbness and tingling in the ulnar distribution on the involved side. Specificity (0.99) Sensitivity (0.75).

The Pressure Provocative Test: The clinician applies pressure at the ulnar nerve at the cubital tunnel with the UE positioned as in the elbow flexion test for 30 seconds. Sensitivity (0.91).

Tinel Sign: Reproduction of tingling and numbness into the 4th and 5th digits with tapping of the ulnar nerve at the cubital tunnel. Specificity (0.98) Sensitivity (0.70).

Outcome Measures

McGowan Score, Louisiana State University Medical Center Score, Bishop Score, and Medical Research Council grade, and Northwick Park Questionnaire are a few outcome measures that have been used.

Management / Interventions

Nonoperative Management: Nonoperative management  has been shown to have at least a 50% success rate with low-stage ulnar irritation. Nonoperative management may include a 4-6 week period of immoblization with the elbow splinted at 45 degrees flexion and full supination. It has been recommended that athletes have active rest from sports. Modalities may be used to treat inflammation. Return to throwing is allowed at 4-6 weeks following absence of symptoms with any daily activities or exercise and return to full ROM and strength.

There is some low level evidence (case report) that has utilized nerve-gliding techniques, segmental joint manipulation and a home program consisting of nerve gliding and light free weight exercises and was able to achieve positive outcomes.

Operative Management: Indications for surgical intervention include failure of conservative treatment and an electrodiagnostic test of less than 39 meters per second across the elbow. Several surgical techniques have been advocated for cubital tunnel syndrome. Techniques include: simple decompression, submuscular anterior transposition, and subcuatneous anterior ulnar transposition.  Results found no difference in motor nerve-conduction velocityies or clinical outcome scores between simple decompression and ulnar nerve transposition.

Differential Diagnosis

Differential diagnosis should include cervical radiculopathy, thoracici outlet syndrome, MCL insufficiency, tophaceous gout, and calcium pyrophosphate dehydrate crystal deposition.

Key Evidence

Zlowodzki and Chan

Meta-Analysis of four RCT comparing simple decompression with anterior ulnar nerve transpostions. There were no significant differences between simple decompression and anterior transposition in terms of the clinical scores in those studies (standard mean difference in effect size = -0.04 [95% CI = -0.36 to 0.28], p = 0.81. Authors did not find significant heterogeneity across the studies. Two reports presented postoperative motor nerve conduction vlocities; they showed no significant difference between the the procedures. Conclusion: Data suggests that simple decompression is a reasonable alternative to anterior transposition for surgical management of ulnar nerve compression at the elbow.

Resources

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Case Report

Coppieters and Bartholomeeusen

The objective was to discuss the diagnosis and treatment of a patient with cubital tunnel syndrome and to illustrate novel treatment modalities for the ulnar nerve and its surrounding structures and target tissues. The patient was a 17 year old female with traumatic onset of cubital tunnel syndrome. She had pain around the elbow and paresthesia in the ulnar nerve distribution. Electrodiagnostic tests were negative.  Segmental cervicothoracic motion dysfunctions were presentwhich were regarded as contributing factors hindering natural recovery. Six treatments included nerve-gliding techniques, segmental joint manipulation, and a home program of nerve gliding and light free-weight exercises. Substantial improvement was recorded on both the impairment and functional level. Symptoms did not recur within 10-month follow-up period. Pain and disability had completely resolved.

References

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