Mononeuropathy

Alternative names
Neuropathy - isolated

Definition
Mononeuropathy involves loss of movement or sensation to an area caused by damage to a single nerve or nerve group.

Causes, incidence, and risk factors

Mononeuropathy involves damage or destruction of an isolated nerve or nerve group. It is a type of peripheral neuropathy (damage to nerves outside the brain and spinal cord).

Mononeuropathy is most often caused by damage to a local area resulting from injury or trauma, although occasionally systemic disorders may cause isolated nerve damage (as with mononeuritis multiplex). The usual causes are direct trauma, prolonged pressure on the nerve, and compression of the nerve by swelling or injury to nearby body structures.

The damage includes destruction of the myelin sheath (covering) of the nerve or of part of the nerve cell (the axon). This damage slows or prevents conduction of impulses through the nerve.

Mononeuropathy may involve any part of the body. Some of the common forms of mononeuropathy include:

     
  • Sciatic nerve dysfunction  
  • Common peroneal nerve dysfunction  
  • Radial nerve dysfunction  
  • Ulnar nerve dysfunction  
  • Cranial mononeuropathy VI  
  • Cranial mononeuropathy VII  
  • Cranial mononeuropathy III; compression type  
  • Cranial mononeuropathy III; diabetic type  
  • Axillary nerve dysfunction  
  • Carpal tunnel syndrome  
  • Femoral nerve dysfunction  
  • Tibial nerve dysfunction

Symptoms

     
  • Impairment of sensation in a body part supplied by a specific nerve       o Numbness, decreased sensation       o Tingling, burning, pain, abnormal sensations       o Loss of sensation  
  • Impairment of movement in one muscle supplied by a specific nerve       o Weakness       o Paralysis (total loss of movement)

Note: Symptoms are isolated to one location.

Signs and tests
Neuromuscular examination of the affected area may indicate which nerve is involved. Reflexes may be abnormal in the area. Symptoms are isolated to one nerve area.

Tests for mononeuropathy may include the following:

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

Testing is guided by the suspected cause of the dysfunction, as suggested by the history, symptoms and pattern of symptom development. Testing may include various blood tests, X-rays, and scans.

Treatment
Treatment is aimed at maximizing the ability to use the affected body part. The cause should be identified and treated as appropriate. In some cases, no treatment is required and recovery is spontaneous. Vascular lesions (injuries to an artery) can often affect a single nerve, and in these cases the cause of the vasculopathy (such as High blood pressure or Diabetes) should be treated.

If there is no history of trauma to the area, conservative treatment is indicated if there was sudden onset, minimal sensation changes, no difficulty in movement, and no test results indicating degeneration of the nerve axon.

Corticosteroids injected into the area may reduce swelling and pressure on the nerve in some cases. Surgical intervention is indicated if the symptoms are caused by entrapment of the nerve. Surgical removal of lesions that press on the nerve may help in some cases.

CONTROL OF SYMPTOMS:
Over-the-counter analgesics or prescription pain medications may be needed to control pain (neuralgia). Various other medications may reduce the stabbing pains that some people experience, including gabapentin, phenytoin, carbamazepine, or tricyclic antidepressants such as amitriptyline. Whenever possible, the use of these drugs should be avoided or minimized to reduce the risk of medication side effects.

Physical therapy exercises may be appropriate for some people to maintain muscle strength. Orthopedic assistance may maximize the ability to use the affected body part. This may include the use of braces, splints, or other appliances.

Vocational counseling, occupational therapy, occupational changes, job retraining, or similar interventions may be recommended if appropriate.

Expectations (prognosis)

Mononeuropathy is rarely fatal, but it may be disabling and painful. If the cause of the nerve dysfunction can be identified and successfully treated, there is a possibility of full recovery.

The extent of disability varies from no disability to partial or complete loss of movement or sensation. Nerve pain may be quite uncomfortable and persist for a prolonged period of time.

Complications

     
  • Recurrent or unnoticed injury to the affected area due to lack of sensation  
  • Mild to severe deformity  
  • Decreased self-esteem  
  • Medication side effects

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

Prevention
Avoiding pressure or traumatic injury may prevent many forms of mononeuropathy. Treating underlying medical conditions such as High blood pressure or Diabetes also decreases risk of developing the condition.

Johns Hopkins patient information

Last revised: December 3, 2012
by Levon Ter-Markosyan, D.M.D.

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