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Radial nerve dysfunction

Definition

Radial nerve dysfunction is a problem with the radial nerve. Damage to the radial nerve leads to problems with movement or sensation of the back of the arm (triceps), forearm, or hand.

Alternative Names

Neuropathy - radial nerve; Radial nerve palsy; Mononeuropathy

Causes, incidence, and risk factors

Radial neuropathy occurs when there is damage to the radial nerve, which travels down the arm and controls movement of the triceps muscle at the back of the upper arm. It also controls the ability to bend the wrist backward and helps with the movement and sensation of the wrist and hand.

Mononeuropathy means a single nerve is damaged. With mononeuropathy, usually the nerve damage is caused locally. However, body-wide disorders may damage just one nerve.

Causes are:

• Injury
  • "Crutch palsy," caused by improper use of crutches
  • Fracture of the humerus (upper arm bone)
  • Long-term or repeated constriction of the wrist (for example, from wearing a tight watch strap)
  • Pressure caused by hanging the arm over the back of a chair ("Saturday night palsy" if caused by drinking too much alcohol and falling asleep in that position)
  • Pressure to the upper arm from arm positions during sleep or coma
  • Pinching of the nerve during deep sleep, such as when a person is intoxicated
• Long-term pressure on the nerve, usually caused by swelling or injury of nearby body structures

In some cases, no cause can be found.

If other nerves are also affected, the health care provider should look for a medical problem that can affect nerves. Medical conditions such as diabetes and kidney disease can damage nerves.

Symptoms

The following symptoms may occur:

• Abnormal sensations
  • Hand or forearm ("back" of the hand)
  • "Thumb side" (radial surface) of the hand
  • Fingers nearest to the thumb (2nd and 3rd fingers)
• Difficulty straightening the arm at the elbow
• Difficulty bending the hand back at the wrist, or even holding the hand
• Numbness, decreased sensation, tingling, or burning sensation
• Pain

Signs and tests

The health care provider will take a detailed history to find out what you may have been doing just before the symptoms started, and to learn about any other medical problems you may have.

An exam of the arm, hand, and wrist may find:

• Decreased ability to extend the arm at the elbow
• Decreased ability to rotate the arm outward (supination)
• Difficulty lifting the wrist or fingers (extensor muscle weakness)
• Muscle loss (atrophy) in the forearm
• Weakness of the wrist and finger
• Wrist or finger drop

Tests may be needed, depending on the history, symptoms, and findings from the physical exam. Tests for nerve dysfunction may include:

• Different blood tests
• EMG
• MRI of the head, neck, and shoulder to look for other causes
• Nerve biopsy (rarely needed)
• Nerve conduction tests

Treatment

The goal of treatment is to allow you to use the hand and arm as much as possible. The health care provider should find and treat the cause, if possible. In some cases, no treatment is needed and you will recover slowly on your own.

Surgery to remove masses that press on the nerve may help.

Medical causes such as diabetes and kidney disease should be treated.

CONTROL OF SYMPTOMS

Medications may include:

• Over-the-counter analgesics or prescription pain medications to control pain (neuralgia)
• Anticonvulsant medicines (phenytoin, carbamazepine, gabapentin, and pregabalin) or tricyclic antidepressants (amitriptyline) to reduce stabbing pain
• Steroid (prednisone) injections around the nerve to reduce swelling may help some patients.

Whenever possible, avoid or minimize your use of medications to reduce the risk of side effects.

Other treatments include:

• Braces, splints, or other appliances to help you use the hand in severe cases
• Physical therapy to help maintain muscle strength

Occupational therapy and vocational therapy or counseling to suggest changes at the worksite may be needed.

Support Groups

Expectations (prognosis)

If the cause of the nerve dysfunction can be found and successfully treated, there is a good chance that you will fully recover. In some cases, there may be partial or complete loss of movement or sensation.

Nerve pain may be uncomfortable and may last for a long period of time. If this occurs, see a pain specialist to ensure you have access to all pain treatment options.

Complications

• Mild to severe deformity of the hand
• Partial or complete loss of feeling in the hand
• Partial or complete loss of wrist or hand movement
• Recurrent or unnoticed injury to the hand

Calling your health care provider

Call your health care provider if you have had an injury to the arm, and you develop numbness, tingling, or weakness.

Prevention

Avoid prolonged pressure on the upper arm.

References

Weiss LD, Pobre TE. Radial neuropathy. In: Frontera WR, Silver JK, Rizzo TD Jr., eds. Essentials of Physical Medicine and Rehabilitation. 2nd ed. Philadelphia, Pa: Saunders Elsevier;2008:chap 22.