radial paralysis

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 [pah-ral´ĭ-sis] (pl. paral´yses.)
Loss or impairment of motor function in a part due to a lesion of the neural or muscular mechanism; also, by analogy, impairment of sensory function (sensory paralysis). Paralysis is a symptom of a wide variety of physical and emotional disorders rather than a disease in itself. Called also palsy.
Types of Paralysis. Paralysis results from damage to parts of the nervous system. The kind of paralysis resulting, and the degree, depend on whether the damage is to the central nervous system or the peripheral nervous system.

If the central nervous system is damaged, paralysis frequently affects the movement of a limb as a whole, not the individual muscles. The more common forms of central paralysis are hemiplegia (in which one entire side of the body is affected, including the face, arm, and leg) and paraplegia (in which both legs and sometimes the trunk are affected). In central paralysis the tone of the muscles is increased, causing spasticity.

If the peripheral nervous system is damaged, individual muscles or groups of muscles in a particular part of the body, rather than a whole limb, are more likely to be affected. The muscles are flaccid, and there is often impairment of sensation.
Causes of Central Paralysis. stroke syndrome is one of the most common causes of central paralysis. Although there is usually some permanent disability, much can be done to rehabilitate the patient. Paralysis produced by damage to the spinal cord can be the result of direct injuries, tumors, and infectious diseases. Paralysis in children may be a result of failure of the brain to develop properly in intrauterine life or of injuries to the brain, as in the case of cerebral palsy. Congenital syphilis may also leave a child partially paralyzed. Paralysis resulting from hysteria has no organic basis and is a result of emotional disturbance or mental illness.
Causes of Peripheral Paralysis. Until the recent development of immunizing vaccines, the most frequent cause of peripheral paralysis in children was poliomyelitis. neuritis, inflammation of a nerve, can also produce paralysis. Causes can be physical, as with cold or injury; chemical, as in lead poisoning; or disease states, such as diabetes mellitus or infection. Paralysis caused by neuritis frequently disappears when the disorder causing it is corrected.
paralysis of accommodation paralysis of the ciliary muscles of the eye so as to prevent accommodation.
paralysis a´gitans Parkinson's disease.
ascending paralysis spinal paralysis that progresses upward.
birth paralysis that due to injury received at birth.
brachial paralysis paralysis of an upper limb from damage to the brachial plexus.
bulbar paralysis that due to changes in motor centers of the medulla oblongata; the chronic form is marked by progressive paralysis and atrophy of the lips, tongue, pharynx, and larynx, and is due to degeneration of the nerve nuclei of the floor of the fourth ventricle.
central paralysis any paralysis due to a lesion of the brain or spinal cord.
cerebral paralysis paralysis caused by an intracranial lesion; see also cerebral palsy.
compression paralysis that caused by pressure on a nerve.
conjugate paralysis loss of ability to perform some parallel ocular movements.
crossed paralysis paralysis affecting one side of the face and the other side of the body.
crutch paralysis brachial paralysis caused by pressure from a crutch.
decubitus paralysis paralysis due to pressure on a nerve from lying for a long time in one position.
divers' paralysis decompression sickness.
Erb-Duchenne paralysis paralysis of the upper roots of the brachial plexus due to destruction of the fifth and sixth cervical roots, without involvement of the small muscles of the hand. Called also Erb's palsy.
facial paralysis weakening or paralysis of the facial nerve, as in bell's palsy.
familial periodic paralysis a hereditary disease with recurring attacks of rapidly progressive flaccid paralysis, associated with a fall in (hypokalemic type), a rise in (hyperkalemic type), or normal (normokalemic type) serum potassium levels; all three types are inherited as autosomal dominant traits.
flaccid paralysis paralysis with loss of muscle tone of the paralyzed part and absence of tendon reflexes.
immunologic paralysis former name for immunologic tolerance.
infantile paralysis the major form of poliomyelitis.
infantile cerebral ataxic paralysis a congenital condition due to defective development of the frontal regions of the brain, affecting all extremities.
ischemic paralysis local paralysis due to stoppage of circulation.
Klumpke's paralysis (Klumpke-Dejerine paralysis) atrophic paralysis of the lower arm and hand, due to lesion of the eighth cervical and first dorsal thoracic nerves.
Landry's paralysis Guillain-Barré syndrome.
lead paralysis severe peripheral neuritis with wristdrop, due to lead poisoning.
mixed paralysis combined motor and sensory paralysis.
motor paralysis paralysis of the voluntary muscles.
musculospiral paralysis Saturday night paralysis.
obstetric paralysis birth paralysis.
periodic paralysis
1. any of various diseases characterized by episodic flaccid paralysis or muscular weakness.
progressive bulbar paralysis the chronic form of bulbar paralysis; called also Duchenne's disease or paralysis.
pseudobulbar muscular paralysis pseudohypertrophic muscular dystrophy.
pseudohypertrophic muscular paralysis pseudohypertrophic muscular dystrophy.
radial paralysis Saturday night paralysis.
Saturday night paralysis paralysis of the extensor muscles of the wrist and fingers, so called because of its frequent occurrence in alcoholics. It is most often due to prolonged compression of the radial (musculospiral) nerve, and, depending upon the site of nerve injury, is sometimes accompanied by weakness and extension of the elbow. Called also musculospiral or radial paralysis.
sensory paralysis loss of sensation resulting from a morbid process.
sleep paralysis paralysis occurring at awakening or sleep onset; it represents extension of the atonia of REM sleep into the waking state and is often seen in those suffering from narcolepsy or sleep apnea. Called also waking paralysis.
spastic paralysis paralysis with rigidity of the muscles and heightened deep muscle reflexes and tendon reflexes.
spastic spinal paralysis lateral sclerosis.
tick paralysis progressive ascending flaccid motor paralysis following the bite of certain ticks, usually Dermacentor andersoni; first seen in children and domestic animals in the northern Pacific region of North America, and now seen in other parts of the world.
Volkmann's paralysis ischemic paralysis.
waking paralysis sleep paralysis.

radial paralysis

Etymology: L, radius + Gk, paralyein
paralysis of muscles supplied by the radial nerve, mainly the wrist and finger extensors. See dropped wrist.


(pa-ral'i-sis) (-sez?) plural.paralyses [Gr. paralyein, to disable]
1. Loss of sensation; anesthesia.
2. Loss of purposeful movement, usually as a result of neurological disease (such as strokes, spinal cord injuries, poliomyelitis), drugs, or toxins. Loss of motor function may be complete (paralysis) or partial (paresis), unilateral (hemiplegic) or bilateral (diplegic), confined to the lower extremities (paraplegic) or present in all four extremities (quadraplegic), accompanied by increased muscular tension and hyperactive reflexes (spastic) or by loss of reflexes and tone (flaccid). Synonym: palsy

Patient care

Rehabilitation therapists evaluate the patient's motor and sensory capabilities (muscle size, tone and strength, reflex or involuntary movement, response to touch or to painful stimuli). The patient must be positioned to prevent deformities. Passive range of motion is performed on the involved extremities to prevent contractures. The patient is repositioned frequently to prevent pressure sores. Local and systemic responses, including fatigue, are evaluated. The rehabilitation team assesses and attends to any self-care deficits the patient may have. Support is offered to the patient and family to help them deal with psychological concerns and the response to grief and loss. Assistance is provided to help the patient in achieving an optimal level of function and in adapting to the disability.

Important concerns include functional positioning, the prevention of deformities secondary to spasticity, and the prevention of injury when sensation is absent. A plan may be prescribed for muscle reeducation and compensatory training. Functional orthoses and assistive technology devices may be necessary to assist the patient in performing self-care and other tasks of daily living.

paralysis of accommodation

Inability of the ciliary muscles to alter the lens to focus on near or far objects.

acoustic paralysis


paralysis agitans

Parkinson disease.

alcoholic paralysis

Paralysis caused by the toxic effect of alcohol on spinal nerves.
Synonym: alcoholic paraplegia

birth paralysis

Loss of function due to nerve injury during delivery. Trauma to the baby during delivery may result in damage to the brachial nerves, facial nerves, or diaphragm. Asymmetrical movements or reflexes of the affected part are present. Prognosis depends on the amount of nerve damage sustained; permanent damage is rare. Most newborn paralyses resolve without sequelae within a few weeks or a few months after birth. Synonym: birth palsy; brachial palsy; obstetrical paralysis

brachial paralysis

Paralysis arising from an injury received at birth to the brachial nerve.

brachiofacial paralysis

Paralysis of the face and an arm.

bulbar paralysis

Paralysis caused by changes in the motor centers of the medulla oblongata. Synonym: progressive bulbar paralysis

complete paralysis

Paralysis in which there is total loss of function and sensation.

compression paralysis

Paralysis due to prolonged pressure on a nerve, e.g., from improper use of a crutch or during sleep.
Synonym: pressure palsy; pressure paralysis

conjugate paralysis

Paralysis of the conjugate movement of the eyes in all directions even though the fixation axis remains parallel.

crossed paralysis

Paralysis affecting muscles of one side of the face and those in the limbs on the opposite side of the body.

crutch paralysis

Paralysis due to pressure on nerves in the axilla caused by improper use of a crutch.

decubitus paralysis

Paralysis caused by compression of a nerve after lying on it, e.g., in sleep or a coma.

diphtheritic paralysis

Paralysis of the muscles of the palate, eyes, limbs, diaphragm, and intercostal muscles as a complication of diphtheria. It is caused by a bacterial toxin.
Synonym: postdiphtheritic paralysis

diver's paralysis

Decompression illness.

Duchenne-Erb paralysis

See: Duchenne-Erb paralysis

facial paralysis

Bell palsy.

facial nerve paralysis

Bell palsy.

familial periodic paralysis

A rare familial disease marked by attacks of flaccid paralysis, often at awakening. This condition is usually associated with hypokalemia but is sometimes present when the blood potassium level is normal or elevated. In affected individuals the condition may be precipitated by administration of glucose in patients with hypokalemia, and by administation of potassium chloride in those with hyperkalemia.


Acetazolamide is used to prevent either hypokalemia or hyperkalemia. Oral potassium chloride is given in attacks accompanied by hypokalemia.

flaccid paralysis

Paralysis in which there is loss of muscle tone, loss or reduction of tendon reflexes, and atrophy and degeneration of muscles. It is caused by lesions of the lower motor neurons of the spinal cord.

general paralysis


ginger paralysis

Jamaica ginger paralysis.

glossolabial paralysis

Paralysis of the tongue and lips occurring in bulbar paralysis.

Gubler paralysis

See: Gubler, Adolphe

hyperkalemic paralysis

A rare form of periodic paralysis characterized by brief (1- to 2-hr) attacks of limb weakness. Respiratory muscles are involved in some cases. “Hyperkalemic” is misleading because the potassium levels may be normal. But, because an attack is precipitated by the administration of potassium, this form of paralysis is better termed “potassium-sensitive periodic paralysis.”


Emergency treatment is seldom necessary. Oral glucose hastens recovery. Attacks may be prevented by acetazolamide or thiazide diuretics.

hypokalemic periodic paralysis

A form of periodic paralysis with onset usually before adulthood. An attack typically comes on during sleep, after strenuous exercise during the day. The weakness may be so pronounced as to prevent the patient from being able to call for help. The attack may last from several hours to a day or more. The diagnosis is established by determining that the serum potassium level is decreased during an attack.


Administration of oral potassium salts improves the paralysis. If the patient is too weak to swallow, intravenous potassium salts are required. Attacks may be prevented by oral administration of 5 to 10 g of potassium chloride daily.

hysterical paralysis

Loss of movement without a demonstrable organic cause. Typically the patient's reflexes are preserved in the affected body part despite its apparent immobility, and bowel and bladder function are preserved. In Western medicine, functional disorders such as this are treated with occupational therapy or supportive psychotherapy; in traditional Chinese medicine, acupuncture is used.
See: Hoover sign

immunological paralysis

The inability to form antibodies after exposure to large doses of an antigen.

incomplete paralysis

Partial paralysis of the body or a part.

infantile paralysis


infantile cerebral ataxic paralysis

Cerebral palsy.

ischemic paralysis

Volkmann contracture.

Jamaica ginger paralysis

Paralysis due to polyneuropathy that affects the muscles of the distal portions of the limbs. It is caused by drinking Jamaica ginger, an alcoholic beverage containing the toxin triorthocresylphosphate.

Klumpke paralysis

See: Klumpke paralysis

Landry paralysis

Flaccid paralysis that begins in the lower extremities and rapidly ascends to the trunk.

laryngeal paralysis

Loss of vocal fold mobility. Common causes include surgical trauma to the recurrent laryngeal nerve or invasion of the nerve by a tumor.
Synonym: vocal paralysis

lead paralysis

Paralysis due to lead poisoning.

leaden paralysis

Extreme fatigue, a symptom of atypical depression.

local paralysis

Paralysis of a single muscle or one group of muscles.

mimetic paralysis

Paralysis of the facial muscles.

mixed paralysis

Paralysis of the motor and sensory nerves.

muscular paralysis

Loss of the capacity of muscles to contract. It may be due to a structural or functional disorder in the muscle at the myoneural junction, in efferent nerve fibers, in cell bodies of nuclei of origin of the brain or of the gray matter of the spinal cord, in conducting pathways of the brain or spinal cord, or in motor centers of the brain.

musculospiral paralysis

Saturday night palsy.

nuclear paralysis

Paralysis caused by lesion of nuclei in the central nervous system.

obstetrical paralysis

Birth paralysis.

ocular paralysis

Paralysis of the extraocular and intraocular muscles.

postdiphtheritic paralysis

Diphtheritic paralysis.

posticus paralysis

Paralysis of the posterior cricothyroid muscles.

potassium-sensitive periodic paralysis

See: hyperkalemic paralysis

Pott paralysis

See: Pott, John Percivall

pressure paralysis

Compression paralysis.

primary periodic paralysis

The occurrence of intermittent weakness, usually following rest or sleep and almost never during vigorous activity. The condition usually begins in early life and rarely has its onset after age 25. The attacks may last from a few hours to a day or more. The patient is alert during an attack.

The causes include hypokalemia, hyperkalemia, thyrotoxicosis, and a form of paramyotonia. Both forms of the disease in which potassium regulation is a factor respond to acetazolamide. The thyrotoxicosis-related disorder is treated by correcting the underlying thyrotoxicosis. Spironolactone is the treatment for cases of paramyotonia congenita with periodic paralysis.

progressive bulbar paralysis

Bulbar paralysis.

pseudobulbar paralysis

Paralysis caused by cerebral center lesions, simulating the bulbar types of paralysis.

pseudohypertrophic muscular paralysis

See: pseudohypertrophic muscular dystrophy

radial paralysis

Saturday night palsy..

Saturday night paralysis

Saturday night palsy.

sensory paralysis

Loss of sensation due to a structural or functional disorder of the sensory end organs, sensory nerves, conducting pathways of the spinal cord or brain, or the sensory centers in the brain.

sleep paralysis

Brief, temporary inability to move or speak when falling asleep or awakening.

spastic paralysis

Paralysis usually involving groups of muscles. It is caused by an upper motor neuron lesion and is characterized by excessive tone and spasticity of muscles, exaggeration of tendon reflexes but loss of superficial reflexes, and positive Babinski reflex.

Sunday morning paralysis

Saturday night palsy..

supranuclear paralysis

Paralysis resulting from disorders in pathways or centers above the nuclei of origin.

tick-bite paralysis

Paralysis resulting from bites of some species of ticks whose saliva contains a toxin, esp. of the genera Ixodes and Dermacentor. It affects domestic animals and humans, esp. children, and causes a progressive ascending, flaccid motor paralysis. Recovery usually occurs after removal of the ticks.

Todd paralysis

See: Todd paralysis

tourniquet paralysis

Paralysis, esp. of the arm, resulting from a tourniquet being applied for too long a time.

vasomotor paralysis

Paralysis of the vasomotor centers, resulting in lack of tone and dilation of the blood vessels.

vocal paralysis

Laryngeal paralysis.

Volkmann paralysis

Volkmann contracture.

wasting paralysis

Spinal muscular atrophy.


1. pertaining to the radius of the forelimb or to the radial aspect of the forelimb as opposed to the ulnar aspect; pertaining to a radius.
2. radiating; spreading outward from a common center.

radial agenesis
a common congenital deformity in animals, particularly in cats. The defect may be uni- or bilateral, causing a marked medial deviation of the lower forelimb.
Enlarge picture
Radial agenesis in a kitten. By permission from Ettinger SJ, Feldman E, Textbook of Veterinary Internal Medicine, Saunders, 2004
radial dysplasia
a developmental disorder of the radius and ulna in which growth rates differ and deformities of the limb result.
radial hemimelia
absence of the radius.
radial paralysis
caused by loss of function of the radial nerve. See Table 14. Manifested by loss of function of extensor muscles and impaired sensory perception in the thoracic limb especially over the dorsum of the paw. Lesions at or distal to the level of the elbow result in difficulty in extending the carpus and foot so that weight may be carried on the dorsum of the foot. Lesions above that level, usually associated with injury to the brachial plexus, also cause an inability to actively extend the elbow (dropped elbow) and the animal cannot bear weight on the limb.