Complete or partial loss of controlled movement.caused by the inability to contract one or more muscles. Weakness, rather than complete loss of movement, is often referred to as paresis. Paralysis may be temporary or permanent, and can affect a range of muscles-from a small facial muscle to many of the maior muscles in the body. Loss of feeling in the affected parts may accompany the inability to move them.
Paralysis of one half of the body is called hemiplegia; paralysis of all four limbs and the trunk is called quadriplegia. Paraplegia ts paralysis of both legs and sometimes part of the trunk. Palsy is an outdated general term for paralysis; it is still used in the names of certain disorders (such as cerebral palsy).
Paralysis may be flaccid, which gives the limbs a floppy appearance or spastic, in which case the affected parts of the body are rigid.
Muscles that control movement of the body are stimulated to contract by impulses originating in the motor cortex of the brain; they travel via the spinal cord and peripheral nerves to reach the muscle. Paralysis may be caused by any form of injury of disorder anywhere along this nerve pathway, or by a muscle disorder.
A very common cause of paralysis is a stroke, in which damage to part of the brain is caused by bleeding from or blood clotting in a blood vessel that supplies that area of the brain. Because motor fibers cross in the brain stem, paralysis occurs on the side opposite to the site of the brain damage.
Hemiplegia can be caused by any brain disorder in which the portion of the brain that controls movement is damaged -by a brain tumor, brain abscess, brain hemorrhage, cerebral palsy , or encephalitis (brain infection). Some forms of paralysis are caused by damage to those parts of the nervous svstem concerned with the fine control of movement (such as the cerebellum and basal ganglia). Parkinson’s disease is caused by lack of dopamine in the basal ganglia.
SPINAL CORD DISORDERS
Paralysis can be caused by damage to the spinal cord from a fractured spine caused by a motor vehicle accident. Pressure on the spinal cord may cause paralysis in disk prolapse or cervical osteoarthritis. Muscles supplied bv nerves below the damaged area are affected
Diseases affecting nerves in the spinal cord (e.g., multiple sclerosis, poliomyelitis, myelitis, Friedreich’ s ataxia, meningitis, and motor neuron disease) may also cause paralysis.
PERIPHERAL NERVE DISORDERS
A range of disorders (known as neuropathies) affects the peripheral nerves and causes paralysis of varying degrees. A neuropathy may be caused by a variety of conditions, including diabetes mellitus, vitamin deficiency, liver disease, cancer, and the toxic effects of some drugs or metals (such as lead); it may also occur as an inherited disorder.
A type of neuropathy that often caused baralysis of the shoulder, arm, or hand is injury to the brachial plexus (a collection of nerves that serves the arm and hand).
Muscular dystrophy causes progressive muscular weakness and may lead to paralysis. Temporary paralysis sometimes occurs in myasthenia gravis.
The underlying cause is treated if possible. Physical therapy is used to prevent joints from becoming locked into useless positions, which is important in both temporary and permanent paralysis. When the paralysis is temporary (such as in a mild stroke), physical therapy is used to retrain and strengthen the muscles and joints so that some degree of mobility is possible after recovery.
For paralyzed people confined to bed or a wheelchair, nursing care is essential to avoid complications (such as bedsores, deep vein thrombosis, urinary tract infections, constipation, and limb deformities) of prolonged immobility. In addition, various aids are available to help the totally or partially paralyzed person.