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Orthopaedics / Hand & wrist

Cubital Tunnel Syndrome

Floyd G. Shon, MD Melvin P. Rosenwasser, MD
Article


Introduction

Cubital Tunnel Syndrome occurs with ulnar nerve entrapment as it crosses the elbow. Careful examination is required to differentiate this condition from nerve entrapment at the wrist - ulnar tunnel syndrome.

Presentation

  • Pain at the medial aspect of the elbow and proximal forearm
  • Numbness along the distribution of the ulnar nerve
  • Weakness in grip strength

Incidence and Epidemiology

This syndrome has been reported after surgery and is associated with use of a blood pressure cuff, tourniquet or with positioning; often in conjunction with a preexisting neuropathy. There is pain with elbow flexion/extension or with throwing activities. This is the most common site of ulnar nerve compression and the second most common site of peripheral nerve entrapment.

Pathophysiology

The ulnar nerve arises from the medial cord of the brachial plexus containing fibers from the C8 and T1 nerve roots. At its proximal aspect, the ulnar nerve lies medial to the axillary/brachial artery to the middle third of the humeral shaft. At this point, it passes through the intermuscular septum (arcade of Struthers) and along the medial head of the triceps muscle towards the ulnar groove (posterior to the medial epicondyle). Within the cubital tunnel, the ulnar nerve lies beneath the fascial arcade between the two heads of the flexor carpi ulnaris (FCU) and anterior to the flexor digitorum profundus (FDP). Proximally, the ulnar nerve sends off an articular branch before innervating the FCU and the ulnar head of the FDP muscle. Compression of the ulnar nerve commonly occurs between the ulnar and humeral heads of the FCU just distal to the medial epicondyle (Osborne's fascia). Other sources of compression include the arcade of Struthers, medial head of the triceps, the aponeurosis of the FCU, synovial hypertrophy, tumor (ganglia or lipomata), aberrant muscles (anconeus epitrochlearis), cubitus valgus, bone spurs and with nerve subluxation during elbow flexion.

Clinical Features

Patients often complain of pain at the medial aspect of the elbow. There is loss of sensation to light touch and vibratory sense at the small and ulnar half of the ring finger, weakness of grip strength and in severe cases, wasting of the intrinsic musculature. With the elbow in flexion, Tinel's sign is positive at the elbow with exacerbation of symptoms during compression (or percussion) near the origin of the FCU (often within one minute).

Signs and symptoms

(According to McGowan):
  • Ulnar neuropathy consists of minor hypesthesia and paresthesia
  • Hypesthesia with weakness of the interossei
  • Complete/partial loss of sensitivity with marked weakness and wasting of the interossei

Diagnostic Evaluation

  • Electrodiagnostic studies are useful in determining the location of nerve compression
  • Significant compression shows a conduction delay greater than 33%

Treatment

Activity modification, splinting in extension and use of nonsteroidal anti-inflammatory drugs may aid in alleviating symptoms; 50% improve spontaneously. Steroid injections are rarely used because of risk of direct injury to the nerve. Surgical treatment for refractory cases includes:
  • Simple decompression
  • Subcutaneous transposition
  • Intramuscular transposition
  • Submuscular transposition or medial epicondylectomy
Decompression, in general, is appropriate for Grade I and II neuropathy, while anterior transposition should be performed for patients with Grade III involvement. In addition to those with severe symptoms, anterior transposition is preferred for cases involving bony deformity or nerve subluxation. Medial epicondylectomy is preferred for associated medial epicondyle nonunion. Sites of compression that should be explored from proximal to distal include:
  • Arcade of Struthers
  • Medial intermuscular septum
  • Medial epicondyle
  • Cubital tunnel
  • Deep flexor - pronator aponeurosis

Bibliography

Eversmann. Entrapment and Compression Neuropathies: Operative Hand Surgery. 3rd ed.; Green DP, (ed.); New York, NY:Churchill Livingstone 1993.

Dellon AL. Review of treatment results for ulnar nerve entrapment at the elbow. J Hand Surg. 1989;14A: 688-700.

George V, Smith AG. Anatomic considerations of the peripheral nerve in compressive neuropathies of the upper extremity. Orthop Clin North Am. April 1996;27(2): 211-218.

Szabo RM. Nerve compression syndromes; Hand Surgery Update. Manske P (ed.), Englewood, Colo. American Society for Surgery of the Hand. 1994.

Tetro AM, Pichora DR. Cubital tunnel syndrome and the painful upper extremity. Hand Clinics. Nov. 1996;12(4): 665-677.