- Also called:
- palsy
paralysis
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What is paralysis?
Paralysis is the loss or impairment of voluntary muscular movement resulting from abnormalities in nervous or muscular tissue, or from metabolic disturbances in neuromuscular function. It can affect the legs and lower body (paraplegia), both arms and legs (quadriplegia), or the lower face, arm, and leg on one side of the body (hemiplegia).
Most diseases that cause paralysis involve structural alterations in nervous or muscular tissue, or lead to metabolic disturbances in neuromuscular function. Some diseases, such as poliomyelitis and polyneuritis, attack lower motor neurons, resulting in paralysis with muscular wasting. Others, such as muscular dystrophy, result in paralysis through primary changes in muscle tissue.
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What are the main types of paralysis?
Paralysis is the loss or impairment of voluntary muscular movement caused by abnormalities of nervous or muscular tissue or by metabolic disturbances in neuromuscular function.
Main types of paralysis:
* Paraplegia Paralysis of the legs and lower part of the body.
* Quadriplegia Paralysis of both arms and both legs.
* Hemiplegia Affects the lower face, arm, and leg muscles on one side of the body. Hemiplegia is commonly caused by stroke, spinal cord injury, brain tumors, and brain infections.4 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
What causes paralysis to happen in the body?
Paralysis is the loss or impairment of voluntary muscular movement caused by abnormalities of nervous or muscular tissue or by metabolic disturbances in neuromuscular function. It occurs when the motor impulses that normally move along the nerve fibres from the spinal cord to muscles are blocked, and, as a result, muscles become limp and cannot contract.
Diseases that cause paralysis can be divided into two main groups depending on whether they entail structural alterations in nervous or muscular tissue, or lead to metabolic disturbances in neuromuscular function. Some examples include poliomyelitis and polyneuritis, Bell palsy, and muscular dystrophy. Additional causes can include spinal cord injuries, stroke, and nervous system diseases.
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How does paralysis affect the muscles and nerves?
Paralysis involves the loss or impairment of voluntary muscle movement due to structural or metabolic abnormalities affecting nervous or muscular tissue. It disrupts the motor system, which includes upper and lower motor neurons, and muscles. Nerve impulses travel from the brain's cerebral cortex through upper motor neurons to the spinal cord, then via lower motor neurons to the neuromuscular junction.
Damage to lower motor neurons results in muscle weakness and wasting due to neuron shrinkage and death, leading to muscle denervation. Diseases such as poliomyelitis and polyneuritis also attack lower motor neurons, resulting in paralysis and muscular wasting. Botulinum toxin blocks acetylcholine release, preventing muscle contraction and causing flaccid paralysis.
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What are some medical conditions that can lead to paralysis?
Paralysis, the loss of muscle function, stems from structural or metabolic issues affecting the nervous or muscular systems. Spinal cord injuries from accidents, falls, or tumors can cause quadriplegia (affecting both arms and legs) or paraplegia (affecting the legs).
Other conditions leading to paralysis include stroke, poliomyelitis, multiple sclerosis, muscular dystrophy, and Bell palsy. Strokes can cause hemiplegia, affecting one side of the body. Polio inflames motor cells of the spinal cord and brainstem. Multiple sclerosis damages the myelin sheath, impairing nerve impulse transmission. Muscular dystrophy causes progressive muscle weakness and atrophy. Bell palsy, a form of facial nerve neuritis, leads to facial muscle paralysis.
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How do doctors diagnose and treat paralysis?
Doctors diagnose paralysis through neurological exams, imaging, and lab tests to identify the cause and extent of muscle impairment. Treatment approaches vary depending on the underlying condition, the type of paralysis, and the patient's overall health.
Rehabilitation is a cornerstone of treatment, employing physical therapy, occupational therapy, and assistive devices to improve motor function and quality of life. Therapies include exercises, heat, massage, and electrical stimulation. For permanent paralysis, functional training helps patients adapt daily activities using adaptive techniques and tools. Psychological counseling is also available to help patients cope with the emotional and social challenges of living with paralysis.
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paralysis, loss or impairment of voluntary muscular movement caused by structural abnormalities of nervous or muscular tissue or by metabolic disturbances in neuromuscular function. Paralysis can affect the legs and lower part of the body (paraplegia) or both arms and both legs (quadriplegia). Sometimes the muscles of the lower face, arm, and leg on only one side of the body are involved (hemiplegia).
Most diseases that cause paralysis can be divided into two main groups depending on whether they entail structural alterations in nervous or muscular tissue, or lead to metabolic disturbances in neuromuscular function. Some act systemically and affect one of the three elements in the motor system (upper neuron, lower neuron, or muscle) more or less extensively and exclusively. More often, however, one element or neighbouring portions of two of the three elements are involved over a limited extent by a single focal lesion.
Paralysis from nervous tissue damage
The most common cause of hemiplegia is damage to the corticospinal tracts and associated motor tracts in one hemisphere of the brain from obstruction (blood clot or thrombosis) or rupture (cerebral hemorrhage) of a major cerebral artery. Brain tumour is another but less common cause of hemiplegia and increases in severity gradually over a period of weeks or months. When the lesion is in the left hemisphere of a right-handed person, the resulting right hemiplegia is often associated with one of the various forms of aphasia, the inability to sound words, to write, or to read.
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Bilateral hemiplegia with pseudobulbar palsy results from diffuse, bilateral brain diseases such as occurs in severe cerebral arteriosclerosis or cerebral vascular syphilis. The terms cerebral palsy and spastic diplegia refer to bilateral hemiplegia resulting from prenatal developmental brain defects or from injury to the brain at birth.
The spinal cord is rarely the site of vascular obstruction or hemorrhage. Common causes of damage to the corticospinal tracts in the cord include deformities of the spinal column from bone and joint disease and from fracture or dislocation of the spine, spinal cord tumours, multiple sclerosis, strokes, and a number of inflammatory and degenerative diseases associated with pernicious anemia. One of the most common causes of progressive spastic paraplegia in persons past middle age is spinal degenerative arthritis, in which an intervertebral disk protrudes into the lower cervical portion of the spinal canal.
Paralysis from muscle tissue damage
Of the diseases that attack lower motor neurons and result in paralysis with muscular wasting, the most common are poliomyelitis and polyneuritis, the former affecting the cell bodies or the bulbar and spinal motor neurons and the latter affecting their peripheral processes. Bell palsy is a peripheral neuritis of unknown cause affecting the facial nerve and resulting in paralysis of all the muscles of one side of the face.
Diseases that result in paralysis through primary changes in muscle tissue are fewer than the above. Of the conditions belonging in this category, muscular dystrophy is one of the few that are apparently confined to the muscles. Muscular dystrophy is a hereditary disease that results in paralysis through primary changes in muscle tissue. It is characterized by progressive, symmetrical muscular weakness and atrophy. Pseudohypertrophic muscular dystrophy is a rare variety of the disease that begins before puberty, is more common in males, and usually progresses to severe disability within a few years. The other types of dystrophy, in general, begin in adolescence or young adulthood, equally affect males and females, and progress more slowly.
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Paralysis from metabolic disease
Muscular weakness without structural alteration in nerve or muscle tissue may be a symptom of disturbances in metabolism arising from a wide variety of causes. Among such conditions are diseases of the endocrine glands, certain intoxications, and several metabolic defects. The most common example of a metabolic disorder in neuromuscular function of unknown cause is myasthenia gravis. Myasthenia gravis is characterized by muscular weakness, without atrophy, which may be mild or severe and either generalized or restricted to a few muscle groups. Muscles innervated by cranial nerves usually are affected. Weakness results from a localized defect in the chemical processes involved in the transmission of impulses from motor nerve endings to muscle fibres. Several medications, including neostigmine, may benefit individuals with the disease.