A general classification of disorders involving damage or destruction of nerves, not including the nerves of the brain or spinal cord.

Alternative Names

Peripheral neuritis; Neuropathy - peripheral; Neuritis - peripheral

Causes, incidence, and risk factors

Peripheral neuropathy (peripheral neuritis) is fairly common. The incidence varies with the specific type of neuropathy. Peripheral neuropathy is not a specific, separate disease. It is a manifestation of many conditions that can cause damage to the peripheral nerves. The peripheral nervous system includes all nerves not in the central nervous system (CNS), which includes the brain and spinal cord. The peripheral nervous system is the nerve system used by the CNS to communicate with the rest of the body, including the cranial nerves and the nerves supplying the internal organs, muscles, skin, and other areas. Damage to the nerves of the peripheral nervous system impairs communication between the CNS and the rest of the body. Symptoms depend on whether the disorder affects the sensory nerve fibers (the fibers that transmit sensory information from the affected area to the brain and spinal cord) or motor nerve fibers (the fibers that transmit impulses from the brain and spinal cord to the area) or both. Damage to sensory fibers results in changes in sensation ranging from perception of abnormal sensations , pain, decreased sensation , lack of sensation , or an inability to determine joint position sense in the area. Sensation changes usually begin in the feet or hands and progress toward the center of the body with peripheral neuropathies that include degeneration of the axon portion of the nerve cell or loss of myelin surrounding the axon. Damage to the motor fibers impairs movement or function of the area supplied by the nerve, because impulses to the area are blocked. Impaired nervous stimulation to a muscle group results in weakness, decreased movement or control of movement. Loss of nerve function causes structural changes in muscle, bone, skin, hair, nails, and body organs. Structural changes are caused by lack of nervous stimulation, not using the affected area, immobility, and lack of weight bearing. There is muscle weakness and muscle wasting (atrophy, loss of muscle mass). Recurrent, unnoticed injury to the area may occur due to lack of ability to feel, causing injury which may result in infection or structural damage. Changes include ulcer formation, poor healing, loss of tissue mass , scarring, and deformity. The autonomic nervous system is the part of the peripheral nervous system that controls involuntary or semi-voluntary functions, such as control of internal organs. Damage to nerves of the autonomic nervous system causes changes in functioning of these organs, resulting in symptoms such as blurred vision , decreased ability to sweat ( anhidrosis ), dizziness or fainting associated with a fall in blood pressure , decreased ability to regulate body temperature, disturbances in function of the stomach or bowel, disturbances of bladder function, and sexual dysfunction. Peripheral neuropathy may involve damage to a single nerve or nerve group ( mononeuropathy ) or may multiple nerves (polyneuropathy). Neuropathy involves damage to the axon of the nerve cell or the myelin sheath. Causes include nerve destruction from various disorders and nerve destruction caused by pressure. Degeneration of the axon slows or blocks conduction at the point of the degeneration. Demyelination (destruction of the myelin sheath around the nerve cell) greatly decreases the speed of impulse conduction through the nerve. In some cases, no detectable cause of the neuropathy can be identified. Pressure injury may be caused by direct injury or compression of the nerve by other nearby body structures. Compression can be caused by peripheral nerve tumors (rare), tumors that press on nerve tissue (rare), abnormal bone growth, or cysts or collections of fluid or tissue that press on nerves. Compression can also be caused by pressure from casts , splints , braces, crutches, or other appliances. Prolonged periods in cramped positions may cause nerve injury. Nerve damage may occur after surgery due to being in one position for a prolonged period of time. Entrapment neuropathy includes compression of a nerve where it passes through a narrow space. The mechanical factors may be complicated by ischemia (lack of oxygen that results from decreased blood flow) in the area. Systemic causes of neuropathy include disorders affecting the connective tissues of the nerves, disorders affecting the blood supply to the nerve cells, hereditary conditions, metabolic or chemical disorders, and other disorders that damage nerve tissue. Some of the specific conditions associated with neuropathy include:

Signs and tests

Treatment

Treatment goals may be to determine underlying cause and treat it, cure of the disorder (if possible), maximal self-care ability and independence, and control of symptoms. The cause should be identified and treated whenever possible. This may include control of blood-sugar levels for diabetics, abstinence from alcohol, nutritional supplements, surgical decompression or other surgical treatments, or medical treatment of conditions. Physical therapy, vocational therapy, occupational therapy, and orthopedic interventions may be recommended to promote self care ability and independence. For example, exercises and retraining may be used to increase muscle strength and control. Appliances such as wheelchairs, braces, and splints may improve mobility or ability to use an affected extremity. Safety is an important consideration for people with neuropathy. Lack of muscle control or decreased sensation increase the risk of falls or other injury. The person may be unable to perceive a potential source of injury because of decreased sensation. Safety measures for people experiencing difficulty with movement may include railings, various appliances, removal of obstacles (such as loose rugs that may slip on the floor), and other measures as appropriate. Safety measures for people having difficulty with sensation include awareness of the lack of sensation and compensation through other measures. Specific measures may include use of adequate lighting (including lights left on at night), testing of water temperature before bathing or immersing parts of the body in water, use of protective shoes (no open toes, no high heels, and so on), and similar measures. Shoes should be checked often for grit or rough spots that may cause injury to the feet. People with decreased sensation should check their feet (or other affected area) frequently for bruises, open skin areas, or other injury, which may go unnoticed and become severely infected. People with neuropathy (especially those with polyneuropathy or mononeuropathy multiplex ) are prone to new nerve injury at pressure points (knees and elbows, for example). They should avoid prolonged pressure on these areas from leaning on the elbows, crossing the knees, or similar positions. Over-the-counter analgesics or prescription pain medications may be needed to control pain ( neuralgia ). Anticonvulsants (phenytoin, carbamazepine, gabapentin), tricyclic antidepressants, or various other medications may be used to reduce the stabbing pains that some people experience. Whenever possible, their use should be avoided or minimized to reduce the risk of side effects of medications. Adjusting position, using frames to keep bedclothes off of a tender body part, or other measures may be helpful to control pain. Autonomic changes may be treated symptomatically. They may be difficult to treat or respond poorly to treatment. Use of elastic stockings and sleeping with the head elevated may reduce postural hypotension . Fludrocortisone or similar medications may be beneficial in reducing postural hypotension for some people. Medications that increase gastric motility (such as metoclopramide), eating small frequent meals, sleeping with the head elevated, or other measures may be used to treat reduced gastric motility. Manual expression of urine (pressing over the bladder with the hands), intermittent catheterization, or medications such as bethanechol may be necessary to treat bladder dysfunction. Impotence , diarrhea , constipation , or other symptoms are treated as appropriate.

Expectations (prognosis)

If the cause of the peripheral neuropathy can be identified and successfully treated and if damage is limited to the axon or myelin sheath (leaving the cell body intact), there is a possibility of full recovery from peripheral neuropathy. In some cases, there may be partial or complete loss of movement , function, or sensation resulting in disability. Nerve pain may be quite uncomfortable and may persist for a prolonged period of time. In some instances, the neuropathy may cause severe, life-threatening symptoms.

Complications

Calling your health care provider

Call your health care provider if symptoms of peripheral neuropathy are present. In all cases, early diagnosis and treatment increases the possibility that symptoms can be controlled. Emergency symptoms include irregular or rapid heartbeats, difficulty breathing , difficulty swallowing , and fainting .

Prevention

The prevention varies depending on the cause.