Ulnar nerve dysfunction Health Article

Definition

Ulnar nerve dysfunction is a problem with the nerve that travels from the wrist to the shoulder, which leads to movement or sensation problems in the wrist and hand.

Alternative Names

Neuropathy - ulnar nerve; Ulnar nerve palsy

Causes, incidence, and risk factors

Ulnar nerve dysfunction is a common form of peripheral neuropathy. It occurs when there is damage to the ulnar nerve, which travels down the arm. The ulnar nerve is near the surface of the body where it crosses the elbow, so long-term pressure on the elbow may cause damage.

The damage involves the destruction of the nerve covering (myelin sheath) or part of the nerve (axon). This damage slows or prevents nerve signaling.

A problem with one single nerve group (such as the ulnar nerve) is called mononeuropathy. The usual causes are:

• Direct injury
• Long-term pressure on the nerve
• Pressure on the nerve caused by swelling or injury of nearby body structures

Entrapment involves pressure on the nerve where it passes through a narrow structure.

The ulnar nerve is commonly injured at the elbow because of elbow fracture or dislocation. Prolonged pressure on the base of the palm may also damage part of the ulnar nerve. Temporary pain and tingling of this nerve is common if the elbow is hit, producing the experience of hitting the "funny bone" at the elbow.

In some cases, no cause can be found.

Symptoms

• Abnormal sensations in the 4th or 5th fingers, usually on the palm side
• Numbness, decreased sensation
• Pain
• Tingling, burning sensation
• Weakness of the hand

Pain or numbness may awaken you from sleep. Activities such as tennis or golf make the condition worse.

Signs and tests

An exam of the hand and wrist can reveal ulnar nerve dysfunction. Signs may include:

• "Claw-like" deformity (in severe cases)
• Difficulty moving the fingers
• Wasting of the hand muscles (in severe cases)
• Weakness of wrist and hand bending

A detailed history may be needed to determine the cause of the neuropathy.

Tests may include:

• Blood tests
• Imaging scans
• Nerve conduction tests
• Recording of the electrical activity in muscles (EMG)
• X-rays