Definition

Distal median nerve dysfunction is a form of peripheral neuropathy that affects the movement of or sensation in the hands.

A common type of distal median nerve dysfunction is carpal tunnel syndrome.

Alternative Names

Causes, incidence, and risk factors

Dysfunction of one nerve group, such as the distal median nerve, is called mononeuropathy. Mononeuropathy means there is a local cause of the nerve damage, although occasionally systemic (body-wide) disorders may cause isolated nerve damage (for example, mononeuritis multiplex).

Distal median nerve dysfunction occurs when the nerve is inflamed, trapped, or injured by trauma. Trapping (entrapment) involves pressure on the nerve where it passes through a narrow area. Wrist fractures may injure the median nerve directly or may increase the risk for trapping a nerve later on.

The nerve can also be compressed at the wrist by tendonitis, arthritis, or conditions that affect connective tissue or cause deposits in the tissues (such as multiple myeloma, pregnancy, acromegaly, and hypothyroidism). These mechanical factors may cause nerve disease, blocking blood flow to the area.

In some cases, no cause can be identified.

See also: Carpal tunnel syndrome

Symptoms

• Sensation changes of the thumb and first 2 fingers
  • Numbness, decreased sensation
  • Tingling, burning sensation
  • Waking up at night with wrist or hand pain (may be severe)
• Weakness of the hand
  • Dropping things
  • Difficulty grasping objects

Signs and tests

Examination may show decreased sensation in the thumb side (radial) fingers of the hand. There may be weakness of the thumb and difficulty using it to pinch.

Tests that reveal distal median nerve dysfunction may include:

• EMG (a recording of electrical activity in muscles)
• Nerve conduction tests
• Nerve biopsy (rarely needed)

Tests are guided by the suspected cause of the dysfunction as suggested by the patient's history, symptoms, and pattern of symptom development. They may include various blood tests, x-rays, imaging scans, or other tests and procedures.

Treatment

Treatment is aimed at correcting the underlying cause.

If the median nerve is affected by carpal tunnel syndrome, a wrist splint can reduce further injury to the nerve and help alleviate symptoms. In some cases, no treatment is required and recovery is spontaneous. Over-the-counter or prescription medication may be needed to control nerve pain (neuralgia).

If other nerves are also affected, it is necessary to look for an underlying medical problem that can affect nerves. Medical conditions such as diabetes and kidney disease can damage nerves. In these cases, treatment is directed at the underlying medical condition.

Physical therapy exercises may be appropriate for some people to maintain muscle strength. Orthopedic assistance may maximize the ability to use the hand and may include braces, splints, or other appliances. Vocational counseling, occupational therapy, occupational changes, job retraining, or measures may be recommended.

Support Groups

Expectations (prognosis)

If the cause of the nerve dysfunction can be identified and successfully treated, there is a possibility of full recovery. In some cases, there may be partial or complete loss of movement or sensation. Nerve pain may be severe and persist for a prolonged period of time.

Complications

• Partial or complete loss of hand movement
• Partial or complete loss of sensation in the fingers
• Recurrent or unnoticed injury to the hand

Calling your health care provider

Call your health care provider if symptoms of distal median nerve dysfunction are present. Early diagnosis and treatment increase the chance of controlling symptoms.

Prevention

Prevention varies depending on the cause. In patients with underlying diabetes, controlling blood sugar may reduce the risk of developing nerve disorders.

In occupations that require repetitive wrist movements, a change in the way the job is performed may be necessary. Frequent breaks in activity, "wrist rests" on keyboards, and other measures may reduce the risk of distal median nerve dysfunction. When possible, avoid prolonged repetitive movement of the wrist.

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