Paralysis refers to temporary or permanent loss of voluntary muscle movement in a body part or region.
People can experience localized, generalized, partial, or complete paralysis.
In this article, learn more about the types of paralysis, their causes, and the support that may be available.
Paralysis is the loss of voluntary muscle function in one or more parts of the body as a result of damage to the nervous system.
The nervous system has two parts:
- the central nervous system (CNS), which includes the brain and spinal cord.
- the peripheral nervous system (PNS), which contains the nerves outside of the CNS
The nerve cells, or neurons, in the PNS serve several functions.
Motor neurons, for instance, regulate muscle movement. Sensory neurons send information — about pressure, pain, and temperature, for example — to the CNS.
Paralysis occurs when nerve signals are interrupted as a result of damage to the nerves, spinal cord, or brain.
Doctors classify paralysis based on the following characteristics:
The degree of muscle function loss determines the severity of paralysis.
Partial paralysis, or paresis, causes significant muscle weakness and impaired movement. However, people with paresis retain a small degree of control over the affected muscles.
Complete paralysis occurs when a person cannot move the affected body part.
Duration refers to how long the paralysis lasts.
Some medical conditions, such as sleep paralysis, stroke, and Bell’s palsy, can cause temporary paralysis. Over time, people can regain partial or complete control over the affected muscles.
Other conditions that can cause the problem temporarily include hyperkalemic or hypokalemic periodic paralysis. They occur as a result of mutations that affect the CACNA1S or SCN4A genes.
These genes carry instructions for making proteins that transport sodium and calcium ions into and out of muscle cells. The flow of ions within muscle cells helps produce muscle contractions and movement.
Disruptions in the ion flow can lead to periodic episodes of muscle weakness and paralysis.
Meanwhile, severe head or neck injuries and neuromuscular disorders can lead to permanent paralysis.
Localized paralysis affects a small area of the body, such as the face, hands, or feet.
Generalized paralysis affects a larger area, including multiple parts of the body.
Types of paralysis include:
- Monoplegia: This affects one area, such as one arm or leg.
- Hemiplegia: This affects one arm and one leg on the same side of the body.
- Paraplegia: Also called lower body paralysis, this affects both legs and sometimes the hips and organs in the lower abdomen.
- Quadriplegia: This affects both arms and legs, and sometimes muscles in the trunk, the functions of internal organs, or both.
Damage to the spinal cord is the most common cause of paraplegia.
Flaccid paralysis damages the lower motor neurons that stimulate skeletal muscle movement. Over time, the muscles shrink or deteriorate.
Flaccid paralysis is a common complication of polio, according to the Centers for Disease Control and Prevention (CDC).
Other causes include inflammation of the spinal cord, also called myelitis, and Guillain-Barré syndrome, a rare autoimmune disorder in which the immune system attacks the PNS.
Spastic paralysis causes muscle stiffness, involuntary spasms, and muscle weakness. This form of paralysis can result from spinal cord injuries, amyotrophic lateral sclerosis (ALS), stroke, or hereditary spastic paraplegia.
Symptoms vary, depending on the type and cause of the issue. The most common paralysis symptom is the loss of muscle function in one or more parts of the body.
Other symptoms that may accompany paralysis include:
- numbness or pain in the affected muscles
- muscle weakness
- visible signs of muscle loss (muscle atrophy)
- involuntary spasms or twitches
According to the results of the 2013 U.S. Paralysis Prevalence and Health Disparities Survey, the most common causes of paralysis in the United States include:
- spinal cord injury
- cerebral palsy
- multiple sclerosis
Muscle weakness and paralysis result from damage to the nervous system, which any of the health problems above can cause.
A healthy nervous system sends information back and forth between the brain and the rest of the body. Signals from the brain travel down the spinal cord and into the peripheral nerves throughout the body.
The peripheral nerves regulate numerous functions, including:
- automatic functions, such as breathing and digestion
- voluntary muscle movements, such as walking and chewing
- sensory functions, such as pain, temperature, and pressure detection
Damage to any part of the nervous system can have severe effects on a person’s overall health and quality of life.
Some other possible causes of nervous system damage and resulting muscle weakness or paralysis include:
- brain or spinal cord tumors
- infections, such as meningitis, encephalitis, and polio
- spina bifida, or the incomplete development of the brain, spine, or spinal cord
- motor neuron diseases, such as ALS and primary lateral sclerosis
- autoimmune diseases, including Guillain-Barré syndrome and lupus
- inherited disorders, including spinal muscular atrophy and hypo- or hyperkalemic partial paralysis
Certain species of tick produce neurotoxins that can cause muscle weakness and acute paralysis of the feet in humans.
The effects of the neurotoxins gradually move up the body.
Most people make a full recovery after the tick is removed. However, without any intervention, tick paralysis eventually leads to respiratory failure.
Currently, no cure for paralysis exists. However, depending on the cause and type of the issue, some people experience partial or complete recovery.
Temporary paralysis, such as that caused by Bell’s palsy or stroke, may resolve on its own without medical treatment.
Also, when paralysis results from a spinal cord injury or chronic neurological condition, a person may recover partial muscle control.
Although rehabilitation does not cure paralysis completely, it can help prevent symptoms from worsening.
Available treatments include:
- physical therapy
- occupational therapy
- mobility devices, such as braces, walkers, and wheelchairs
- surgical amputation
- nerve transfer surgery
Emotional and social support can also play vital roles in a person’s treatment.
Paralysis is the temporary or permanent loss of movement in one or more parts of the body.
Many people with paralysis do not regain full mobility or sensation in the affected area. However, physical therapy, mobility devices, and social and emotional support can help improve the quality of life.
Medication and surgery can often help, as well. A doctor will base treatment recommendations on the severity and the underlying cause of a person’s paralysis.