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Alternative Names
neuropathy - distal median nerve
Definition
A form of peripheral neuropathy (disease of the nerves) involving impaired movement and/or sensation of the thumb caused by damage to the distal median nerve.
Causes, Incidence and Risk Factors
Distal median nerve dysfunction occurs when there is damage to the distal portion of the median nerve, which travels down the arm and provides movement and sensation to the thumb. (The distal portion is the part closest to the hand.) Carpal tunnel syndrome, another form of median nerve dysfunction, is one of the more common peripheral neuropathies.
Dysfunction of a single nerve group, such as the distal median nerve, is classed as mononeuropathy. Mononeuropathy implies a local cause of the nerve damage, although occasionally systemic disorders may cause isolated nerve damage (such as occurs with mononeuritis multiplex). The usual causes are direct trauma, prolonged pressure on the nerve, and compression of the nerve by nearby body structures. Entrapment involves pressure on the nerve where it passes through a narrow structure.
Wrist fractures may injure the median nerve. The nerve may be compressed at the wrist because of tendonitis, arthritis, or conditions that affect connective tissue or cause deposits in the tissues (such as multiple myeloma, pregnancy, acromegaly, and hypothyroidism). In some cases, no detectable cause can be identified. These mechanical factors may be complicated by lack of oxygen from decreased blood flow (ischemia) in the area.
Carpal tunnel syndrome may be associated with entrapment of the nerve following prolonged or repeated pressure on the wrist area (such as may occur with repetitive wrist movements). This is a fairly common occupational or recreational injury.
Symptoms
sensation changes of the first 3 fingers 

• numbness, decreased sensation
• tingling, burning sensation
• pain (may be severe)
• abnormal sensations
• weakness of the hand 
• weak grip
• difficulty grasping objects

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

Treatment
Treatment is aimed at maximizing independence and ability to function at work and home. The cause should be identified and treated as appropriate. In some cases, no treatment is required and recovery is spontaneous.
If there is no history of trauma to the area, conservative treatment is indicated by sudden onset, minimal sensation changes and no difficulty in movement, and no test results indicating degeneration of the nerve axon (nerve fiber). Corticosteroids injected into the area may reduce swelling and pressure on the nerve in some cases.
Surgical intervention is indicated if the disorder is chronic (long term) or symptoms are worsening, if there is difficulty with movement, or if there is test evidence that nerve axon degeneration is present. Surgical decompression may be recommended if the symptoms are caused by entrapment of the nerve. Surgical removal of lesions that press on the nerve may benefit some cases.
CONTROL OF SYMPTOMS:
Over-the-counter or prescription analgesics may be needed to control pain (neuralgia). Other medications, including phenytoin, carbamazepine, or tricyclic antidepressants such as amitriptyline, may reduce the stabbing pains that some persons experience. Whenever possible, their use should be avoided or minimized to reduce the risk of developing medication side effects.
Physical therapy exercises may be appropriate for some persons to maintain muscle strength. Orthopedic assistance may maximize the ability to use the hand. This may include use of braces, splints, or other appliances. Vocational counseling, occupational therapy, occupational changes, job retraining, or similar interventions may be recommended.

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, resulting in various extent of disability. 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

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

Fuente: Adam.com