Polyneuropathy

[Mary Mallozziberg]

Polyneuropathy is the simultaneous malfunction of many peripheral nerves throughout the body.

Infections, toxins, drugs, cancers, nutritional deficiencies, and other disorders can cause many peripheral nerves to malfunction.
Sensation, strength, or both may be impaired, often in the feet or hands before the arms, legs, or trunk.
Doctors base the diagnosis on results of electromyography, nerve conduction studies, and blood and urine tests.
If treating the underlying disorder does not relieve symptoms, physical therapy, drugs, and other measures may help.

(See also Overview of the Peripheral Nervous System.)
Polyneuropathy may be

Acute (beginning suddenly)
Chronic (developing gradually, often over months or years)

[Mary Mallozziberg]

A general degeneration of peripheral nerves that spreads toward the center of the body.

[Dorothey Allen]

A polyneuropathy is a diffuse peripheral nerve disorder that is not confined to the distribution of a single nerve or a single limb and typically is relatively symmetrical bilaterally. Electrodiagnostic tests should always be done to classify the nerve structures involved, distribution, and severity of the disorder and thus help identify the cause. Treatment is directed toward correcting the cause.
Some polyneuropathies affect primarily motor fibers. They include

Immune-mediated disorders (eg, Guillain-Barr#233; syndrome, multifocal motor neuropathy with conduction block)
Lead toxicity
Dapsone use
Tick bite
Porphyria
Spinal muscular atrophy

Others affect primarily sensory fibers. They include

Dorsal root ganglionitis of cancer
Leprosy
AIDS
Diabetes mellitus
Chronic pyridoxine intoxication

Some disorders can also affect cranial nerves. They include

Guillain-Barr#233; syndrome
Lyme disease
Diabetes
Diphtheria

Certain drugs and toxins can affect sensory or motor fibers or both (see table Toxic Causes of Neuropathies).