Ulnar nerve entrapment

Last updated: June 30, 2023

Summarytoggle arrow icon

Ulnar nerve entrapment occurs when the ulnar nerve is compressed, typically at the elbow or the wrist. Compression at the elbow is called cubital tunnel syndrome; compression at the wrist it is referred to as Guyon's canal syndrome or ulnar tunnel syndrome. The compression causes paresthesias, numbness, and/or pain in the ulnar nerve distribution. Depending on the site of compression, the patient may experience weakness in certain hand muscles. Ulnar entrapment neuropathy may be suspected based on clinical symptoms and signs, but it must be confirmed by electromyography (EMG). Conservative treatment involves NSAIDs, behavior modification, and bracing. Severe, persistent, or worsening symptoms require surgical decompression.

Overview of ulnar nerve entrapmenttoggle arrow icon

Course of the ulnar nerve

Ulnar neuropathy at the elbow and wrist [1][2]

The ulnar nerve is most commonly compressed at or near the cubital tunnel of the elbow and Guyon canal of the wrist.

Cubital tunnel syndrome Guyon canal syndrome
Motor deficit
  • Muscle atrophy and weakness (less common than sensory symptoms)
    • Loss of dexterity
    • Decreased grip strength
    • Difficulty lifting
Sensory deficit

Clinical featurestoggle arrow icon

Motor symptoms

  • Entrapment at the elbow
    • Less common than sensory complaints and range from mild to severe weakness
    • Muscle atrophy and weakness
      • Loss of dexterity
      • Decreased grip strength
      • Difficulty lifting
  • Entrapment at the wrist: weakness and atrophy of the intrinsic hand muscles innervated by the ulnar nerve

Sensory symptoms

  • Entrapment at the elbow
  • Entrapment at the wrist
    • Variable paresthesia or sensory loss of the palmar and dorsal aspects of the medial side of the hand, little finger, and ulnar side of the ring finger
    • Compression of the ulnar nerve at the wrist is divided into three zones and exam findings often correlate with the site of injury.
      • Zone I: lesions proximal to the bifurcation of the ulnar nerve
        • Motor and sensory symptoms (i.e., sensory loss in the palmar surface of the little finger and medial aspect of the ring finger) possible
        • Sensory features similar to those caused by proximal lesions at the elbow
      • Zone II: lesions at the deep motor branch cause motor symptoms only
      • Zone III: lesions at the distal sensory branch cause sensory symptoms only

Physical examination

Proximal and distal lesions of the ulnar nerve lead to claw hand deformity.

Proximal and distal lesions of the ulnar nerve lead to claw hand deformity.

Diagnosticstoggle arrow icon

Treatmenttoggle arrow icon

Referencestoggle arrow icon

  1. Depukat P, Mizia E, Kuniewicz M, et al. Syndrome of canal of Guyon - definition, diagnosis, treatment and complication.. Folia Med Cracov. 2015; 55 (1): p.17-23.
  2. Ulnar Nerve Entrapment at the Elbow (Cubital Tunnel Syndrome). Updated: August 1, 2020. Accessed: June 19, 2023.

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