WHAT IS IT?
Peripheral neuropathy refers to disease, inflammation, or damage to the peripheral nerves.
Peripheral nerves are those that connect the central nervous system (brain and spinal cord) to the sense organs, muscles, glands, and internal organs.
Most neuropathies are caused by damage or irritation to the nerve cell axons (conducting fibers that make up nerves) or to their myelin sheaths (a fatty insulating substance that protects the nerve).
Nerve axons may suffer a thinning, patchy, or complete loss of their myelin sheath resulting in slowed or complete block of electrical impulses.
This degenerative change in one or more nerves can be the result of an injury, dietary deficiency, metabolic upset, poisoning, inflammation from a viral infection, autoimmune disorder (condition in which the immune system mistakenly reacts against the body's own tissues), or a group of inherited diseases.
Neuropathies are classified according to the site, extent, and distribution of damage.
A distal neuropathy starts with damage to the end of a nerve farthest from the brain or spinal cord.
Asymmetrical neuropathy affects nerves at the same locations on each side of the body.
Mononeuropathy (or mononeuritis) indicates damage to a single nerve, while polyneuropathy (or polyneuritis) indicates damage to several nerves.
Neuropathies can also be described according to their underlying cause such as
diabetic neuropathy or alcohol neuropathy.
HOW IS IT DIAGNOSED?
History: Symptoms depend on whether the neuropathy mainly affects sensory nerve fibers or motor nerve fibers. Damage to sensory nerve fibers may result in numbness and tingling. Sensations of cold or pain, often starting in the hands and feet, spread toward the center of the body. Damage to motor fibers may result in muscle weakness and wasting. Symptoms of autonomic nerve damage may include blurred vision, impaired or absent sweating, episodes of faintness associated with falling blood pressure, and disturbances in gastric, intestinal, bladder (incontinence), and sexual (impotence) functions.
Physical exam: There is characteristic weakness and wasting in related areas of the body with a loss of tendon reflexes. When autonomic fibers degenerate, organs of the body may be affected. The skin may be sweaty or dry, hot or cold, pale or flushed, or lesions may erupt.
Tests: Electromyography and nerve conduction tests record electrical activity in the muscles to determine the extent of the damage. Cause of the neuropathy may be determined through blood tests, x-rays, and nerve or muscle biopsy (small amounts of tissue removed for microscopic analysis).
HOW IS IT TREATED?
Treatment is directed toward the underlying cause, primary disease, dietary deficiency, toxic exposure, or mechanical damage to the nerves and limbs. Once the causative factor has been identified and eliminated, the body's natural reparative processes can begin. In addition, physical therapy is important to keep joints loose and muscles stretched.
WHAT MIGHT COMPLICATE IT?
If the cell bodies of the damaged nerves have been destroyed, functional loss (sensory loss or muscle weakness) may become permanent.
PREDICTED OUTCOME
If damaged nerve cell bodies have not been destroyed, and treatment of the underlying cause has been successful, full recovery from neuropathy is possible.
ALTERNATIVES
Peripheral neuropathy is a general finding of the physical exam and is not a specific diagnosis. It must be differentiated from other possible diseases.
APPROPRIATE SPECIALISTS
Neurologist and neurosurgeon.
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