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Cubital tunnel syndrome
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Cubital tunnel syndrome

Contributors: Robert Lachky MD, Eric Ingerowski MD, FAAP
Other Resources UpToDate PubMed


Cubital tunnel syndrome refers to ulnar nerve compression or stretch at the elbow. It is the second most common upper extremity compressive neuropathy (behind carpal tunnel syndrome); cross-sectional studies have shown that it is more common than previously known. The condition affects men and women at roughly the same rate. The mean age of diagnosis is approximately 46 years, although any adult could suffer from this condition.

Symptoms of cubital tunnel syndrome include numbness and paresthesias of the fifth (small finger) and part of the fourth digit (ulnar half of the ring finger) as well as the ulnar dorsal hand. Motor findings include a weak pinch and/or a weak grasp. Eventually, atrophy of the intrinsic or extrinsic hand muscles may be visible.

Cubital tunnel syndrome can be caused by trauma at the elbow as well as by a chronic process of ulnar nerve destabilization, repetitive elbow overuse, and injury of the nerve against the retinaculum. It is usually caused by repetitive elbow flexion, eg, due to an occupation, throwing (athletes), talking on a mobile phone, or sleeping with the elbow flexed.

There are many different anatomic sites of compression of the ulnar nerve proximal to the wrist. The cubital tunnel itself has the following boundaries:
  • Medial – medial epicondyle of humerus
  • Lateral – olecranon process of ulna
  • Roof – formed by fascia of flexor carpi ulnaris and Osborne's ligament (goes from medial epicondyle to olecranon)
  • Floor – formed by posterior and transverse bands of the medial collateral ligament and the elbow joint capsule
Note: In the case of motor weakness, urgent referral to a hand surgeon is advised.


G56.20 – Lesion of ulnar nerve, unspecified upper limb

230631009 – Ulnar nerve entrapment at elbow

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Differential Diagnosis & Pitfalls

  • More proximal lesion (cervical nerve root compression, brachial plexus pathology) – initially comes from anterior rami of C8-T1 nerve roots, then lower trunk and medial cord, then branches become the ulnar nerve in the axilla
  • More distal ulnar nerve compression (Guyon canal syndrome at wrist)
  • Carpal tunnel syndrome
  • Osteoarthritis
  • Radial nerve palsy
  • Thoracic outlet syndrome
  • Fracture
In terms of primary care evaluation, calling a compressive ulnar neuropathy cubital tunnel syndrome is acceptable even though it is technically incorrect. (An example is if the compression is actually at the arcade of Struthers in the arm and not the cubital tunnel of the elbow.) The important thing is that a patient with ulnar motor weakness is referred to a hand surgeon.

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Last Reviewed:06/04/2018
Last Updated:06/26/2018
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Cubital tunnel syndrome
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