The loss of muscular function in a part of the body, caused by damage to the muscles themselves or to a part of the nervous system. Paralysis may vary in severity from affecting a single small muscle to affecting most of the body. Disease of the muscles themselves leads more commonly to weakness than to total paralysis. However, some forms of muscular dystrophy, most of which occur in childhood, can progress to severe and eventually fatal paralysis. There is no effective treatment for these conditions.

Any block in the transmission of impulses from nerves to muscles also may result in paralysis. This occurs in myasthenia gravis, in botulism, and in some other types of poisoning (for example, with "nerve gas").

The peripheral nerves may be injured directly or damaged by disease, including diabetes mellitus, polyarteritis nodosa, cancer, alcoholism, vitamin deficiencies, leprosy, porphyria, and some drug reactions. This damage may lead to weakness or to total paralysis of the muscles supplied by the affected nerves.

The spinal cord may be damaged by a number of conditions, including poliomyelitis, multiple sclerosis, and trauma. The pattern of the resulting paralysis depends on its cause. Severe damage to the spinal cord results in paraplegia---complete paralysis of the legs and the lower part of the body, usually including bladder paralysis. If the spinal cord damaged is in the region of the neck, the arms may be paralyzed as well as the legs---quadriplegia.

Brain damage also may result in paralysis. The most common cause here is a stroke, caused by hemorrhage, thrombosis in the brain, or impairment of cerebral blood flow. The extent of the paralysis is variable, but the most common pattern is partial or complete paralysis of the arm and leg on one side---hemiplegia. Other causes of brain damage include meningitis, encephalitis, syphilis, and brain tumors. Transient paralysis (Todd's paralysis) may occur in a part of the body following an epileptic attack.

Paralysis resulting from division of a major nerve tract in the spinal cord or brain is permanent and irreversible, but that resulting from other diseases may have a more variable prognosis. In "acute infective polyneritis" (the guil-lain-barré syndrome), more or less total paralysis may be followed by complete recovery if the patient survives. In some diseases (such as strokes) the extent of recovery is extremely variable, while in others (such as motor neuron disease) recovery is unknown.

Survival in paralysis depends on the underlying disease and whether or not it affects the respiratory tract muscles and heart muscles. Artificial ventilation may keep alive patients with some diseases (for example, poliomyelitis or acute infective polyneuritis) until the paralysis improves or remits. In some cases a person may never recover the ability to breathe on his own and will remain dependent on respirators for life.

Pa*ral"y*sis (?), n. [L., fr. Gr. , fr. to loosen, dissolve, or disable at the side; beside + to loosen. See Para-, and Loose, and cf. Palsy.] Med.

Abolition of function, whether complete or partial; esp., the loss of the power of voluntary motion, with or without that of sensation, in any part of the body; palsy. See Hemiplegia, and Paraplegia. Also used figuratively.

"Utter paralysis of memory."

G. Eliot.

Mischievous practices arising out of the paralysis of the powers of ownership. Duke of Argyll (1887).


© Webster 1913.

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