Paralysis
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.
Types
Doctors classify paralysis based on the following characteristics:
Severity
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
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.
Location
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 causeTrusted Source of paraplegia.
Symptoms
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)
- stiffness
- involuntary spasms or twitches