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|Classification and external resources|
|Classification and external resources|
Polyneuropathy or symmetrical polyneuropathy (poly- + neuro- + -pathy) is damage or disease affecting peripheral nerves (peripheral neuropathy) in roughly the same areas on both sides of the body, featuring weakness, numbness, pins-and-needles and burning pain. It usually begins in the hands and feet and may progress to the arms and legs; and sometimes to other parts of the body where it may affect the autonomic nervous system. It may be acute (appearing suddenly, progressing rapidly and resolving slowly, or chronic (emerging and developing gradually). A number of different disorders may cause polyneuropathy, including diabetes and some types of Guillain-Barré syndrome.
Sensory polyneuropathy is the condition of having multiple sensory neuropathies, while motor polyneuropathy refers to multiple motor neuropathies. Sensorimotor polyneuropathy or sensory-motor polyneuropathy is the combination of both conditions.
Polyneuropathies can be classified in different ways, such as by cause, by speed of progression, or by the parts of the body involved. Classes of polyneuropathy are also distinguished by which part of the nerve cell is mainly affected: the axon, the myelin sheath, or the cell body.
Evaluation and classification of polyneuropathies begins with a history and physical exam in order to document what the pattern of the disease process is (arms, legs, distal, proximal, symmetric), when they started, how long they have lasted, if they fluctuate, and what deficits and pain are involved. If pain is a factor, and it often is, determining where and how long the pain has been present is important. One also needs to know what disorders are present within the family and what diseases the patient may have. This is vital in forming a differential diagnosis.
Although often diseases are suggested by the physical exam and history alone, testing is still a large part of the diagnosis. Tests which may be employed include electrodiagnostic testing using electromyography, muscle biopsy, serum creatine kinase (CK), and antibody testing. Nerve biopsy is not used much, but is helpful in determining small fiber neuropathy. Other tests may be used, especially tests for specific disorders associated with polyneuropathies.
Acute polyneuropathy can have various causes, including infections, autoimmune reactions, toxins, certain drugs (especially chemotherapy agents), and cancer. When the cause cannot be determined it is called "idiopathic." With drug-induced polyneuropathy, there is a trade-off of risk, benefit, and adverse effects; for example, chemotherapy may cause problems (nausea, vomiting, polyneuropathy, and others), but survival can be longer with it than without it.
Chronic polyneuropathy is often caused by diabetes mellitus or by the excessive use of alcohol (alcoholic polyneuropathy) or by degeneration of connective tissue protecting the nerves as in connective tissue diseases, but a variety of other less common causes are known, including nutritional deficiencies, and liver or kidney failure.
If possible, treatment focuses on the underlying disease. Further, pain medications may be given and physical therapy is used to retain muscle function. Vyndaqel or Tafamidis is a European Medicines Agency approved drug for the treatment of familial amyloid polyneuropathy caused by transthyretin amyloisis.
There is a large differential for polyneuropathies: vitamin deficiency, cancer, toxins, infections (ex. Guillain–Barré syndrome, Lyme disease), liver disease, endocrine disease (including diabetes with diabetic and pre-diabetic neuropathy), amyloidosis, genetic disorders, motor neuron disorders, motor neuropathies, kidney failure, paraneoplastic, polio, porphyria (some types), neurosarcoidosis, spinal muscular atrophy, catecholamine disorders, psychological disorders and many others.