Neuropathy

Neuropathy is a loss of the function of nerves. Symptoms depend on which nerves are damaged. The main motor symptom is weakness, whereas common sensory symptoms are numbness, paresthesias (abnormal sensations such as pricking, tickling, burning, or tingling), and pain. Neuropathy is a common neurological disorder resulting from damage to the peripheral nerves and thus is more often called peripheral neuropathy. Peripheral nerves include the nerves branching off the spine, nerves innervating the head and neck area, and the autonomic nerves regulating functions such as blood pressure and motility of the intestines.

Historically, in the eighteenth and nineteenth centuries, neuropathy was not recognized as a separate disease, but rather diagnosed as progressive paralysis together with many other diseases. In the nineteenth century, many different forms of neuropathy were described as ascending or descending according to the direction in which the disease progressed, because the common thought was that nearly all disorders of the nerves were based on inflammation. A second diagnosis often used was progressive muscular atrophy (degeneration). Due to the work of great nineteenth-century French neurologists such as Jean Martin Charcot and G. B. A. Duchenne, many new diseases were split from this general category of progressive muscular atrophy: various diseases of the muscles, the spinal cord, the brain, and the many diseases of the peripheral nerves, the neuropathies.

Neuropathies can be classified into mononeuropathies when one restricted area is damaged, polyneuropathies if there is damage of the nerves in more areas, and symmetric neuropathies with bilateral manifestations. Another classification is according to which type of nerve is involved. Sensory neuropathies account for damage to nerves carrying sensory information and motor neuropathies for those innervating the muscles.

Common causes of neuropathy are diabetes and alcoholism. Other causes include mechanical pressure such as repetitive strain injuries, direct damage, toxic substances, certain medications, inflammation, autoimmune disorders, and endocrine and hereditary diseases. Recent diagnostic DNA tests have greatly increased our understanding of the complexities of hereditary neuropathies.

Although there is a wide range of causes, the type of damage to the nerves is limited. The nerve is composed of a cell body and a fibrous extension (axon), which conducts electrical nerve impulses. Isolation cells (myelin sheath), which facilitate electrical conduction, surround most of the axons. In toxic or metabolic injuries (e.g., diabetes) the axons and the myelin degenerate, resulting in a numb feeling in the area, the so-called sock or glove hypesthesia. Degeneration of myelin can be due to hereditary, inflammatory, or autoimmune factors and usually shows patchy damage to the myelin sheath.

Treatment of neuropathies involves eliminating or regulating the causes. Surgery can help when a nerve [Page 1144]is entrapped; optimizing drug treatment is required in the case of diabetes. Some drugs are prescribed to relieve symptoms such as burning sensation, pain, and painful contractions of muscles. Physical therapy and splints can also relieve the burden of muscle contractions. Some complementary therapies ([electro]acupuncture) can be useful in alleviating symptoms such as pain.

Most hereditary and autoimmune neuropathies are incurable and often show a gradual deterioration leading to a lifelong use of a wheelchair or chronic pain. The impairment of sensory neuropathies, such as those of diabetes or leprosy, can lead to secondary injuries, infection, gangrene, and limb amputation. Providing the means to increase quality of life and improve self-image and providing emotional support are critical for dealing with the disabilities of neuropathy.

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