Multifocal neuropathy

Alternative names
Mononeuropathy multiplex; Mononeuritis multiplex

Definition
Mononeuritis multiplex is a disorder characterized by simultaneous or sequential damage to more than one nerve group.

Causes, incidence, and risk factors

Mononeuritis multiplex is a form of peripheral neuropathy (damage to nerves outside the brain and spinal cord). It involves isolated damage to at least 2 separate nerve areas. Mononeuritis multiplex is a group of symptoms, not a distinct disease entity.

The underlying disorder affects isolated nerves in multiple, random areas. As the disorder worsens, the damage may become more diffuse and less focused on particular areas, resembling polyneuropathy.

The damage to the nerves involves destruction of the axon (part of the nerve cell), which interferes with nerve conduction at the location of the damage. Common causes include a lack of oxygen caused by decreased blood flow or inflammation of blood vessels. No cause is identified for about one-third of cases.

Diabetes mellitus is a common cause of mononeuritis multiplex. Several other disorders are also associated with mononeuritis multiplex, including (but not limited to) blood vessel diseases such as polyarteritis nodosa and connective tissue diseases such as Rheumatoid Arthritis or Systemic lupus erythematosus. Connective tissue disease is the most common cause in children.

Less common causes include the following:

     
  • Sjogren’s syndrome  
  • Wegener’s granulomatosis  
  • Hypersensitivity (allergic reactions) that cause inflammation of blood vessels:       o Leprosy       o Sarcoidosis       o Amyloidosis       o Multifocal forms of diabetic neuropathy       o Disorders of the blood (such as hypereosinophilia and cryoglobulinemia)

Symptoms

     
  • Numbness and tingling  
  • Abnormal sensation  
  • Burning pain  
  • Lack of or decreased sensation in any part of the body  
  • Difficulty moving a part of the body (paralysis)  
  • Lack of control of movement of a part of the body  
  • Inability to move a part of the body

Specific symptoms vary with the individual nerve involved.

Signs and tests

A detailed history may be required to determine the possible cause of the disorder. Examination and neuromuscular testing may show a specific loss of sensation and movement associated with dysfunction of specific nerves. Reflexes may be abnormal.

Diagnosis of mononeuritis multiplex usually involves deficits of 2 or more isolated, unrelated nerve areas. Common findings may include the following:

     
  • Sciatic nerve dysfunction  
  • Common peroneal nerve dysfunction  
  • Radial nerve dysfunction  
  • Ulnar nerve dysfunction  
  • Femoral nerve dysfunction  
  • Distal median nerve dysfunction  
  • Axillary nerve dysfunction

Tests of nerve conduction velocity usually indicate axonal degeneration. An EMG (test of electrical activity in muscles) may be abnormal. A nerve biopsy may be appropriate for some cases.

Various laboratory tests and procedures may be useful in determining the cause of the condition. The tests that are done to find the cause are suggested by the history, symptoms and pattern of symptom development.

Treatment
The goals of treatment include treatment of the cause if possible, supportive care to maximize independence and control of symptoms. This may include control of blood sugar levels for diabetics, nutritional supplementation, or medical treatments of conditions as appropriate.

To maximize self-care and independence, physical therapy, vocational therapy, occupational therapy and orthopedic interventions may be recommended. For example, exercises and retraining may increase muscle strength and control. Appliances such as wheelchairs, braces, and splints may enhance mobility.

Safety is an important consideration for people with sensation or movement difficulties. Lack of muscle control may increase the risk of falls or other injury. Decreased sensation can also increase the risk of falls. It may also increase the risk of injury because the person is unable to perceive a potential source of harm.

Safety measures for people with movement difficulty may include railings, removal of obstacles (such as loose rugs that may slip on the floor) and other measures as appropriate.

Safety measures for persons with limited sensations include an awareness of the lack of sensation and compensation through other measures. Specific measures may include the use of adequate lighting (including lights left on at night), testing of water temperature before bathing, the use of protective shoes (no open toes or high heels), and similar measures. Shoes should be checked often for grit or rough spots that may injure the feet.

People with decreased sensation should check their feet (or other affected area) frequently for bruises, open skin areas, or other injuries that may go unnoticed and become severely infected because the pain nerves of the area are not signalling the injury.

People with mononeuropathy multiplex are prone to new nerve injury at pressure points such as knees and elbows. They should avoid prolonged pressure on these areas caused by leaning on the elbows, crossing the knees, or holding similar positions.

Over-the-counter analgesics or prescription pain medications may be needed to control pain (neuralgia). Various other medications may be used to reduce the stabbing pains that some people experience, including anticonvulsants (gabapentin, phenytoin, carbamazepine) or tricyclic antidepressants. Whenever possible, use of medications should be avoided or minimized to reduce the risk of side effects.

Positioning, the use of frames to keep bedclothes off of a tender body part, and other measures may be helpful to control pain. Autonomic symptoms may occur and can be treated symptomatically. These may be difficult to treat or respond poorly to treatment, however.

Expectations (prognosis)

If the cause can be identified and successfully treated, and if damage is limited, there is a possibility of full recovery from mononeuritis multiplex. The extent of disability varies from no disability to partial or complete loss of movement, function or sensation.

Nerve pain may be quite uncomfortable and persist for a prolonged period of time. If this occurs, see a pain specialist to ensure that all options for pain treatment are available to you.

Complications

     
  • Recurrent or unnoticed injury to any part of the body  
  • Deformity, loss of tissue mass  
  • Disturbances of organ functions  
  • Decreased self-esteem  
  • Relationship problems associated with impotence

Calling your health care provider
Call your health care provider if you notice signs of mononeuritis multiplex.

Prevention
Prevention techniques vary depending on the specific disorder. Proper diet and use of medication for Diabetes may help prevent neuropathy from developing.

Johns Hopkins patient information

Last revised: December 4, 2012
by Harutyun Medina, M.D.

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