Paralysis is a condition in which a person loses the ability to make voluntary muscle movements due to a problem in the nervous system. Normally, nerves send signals from the brain to the muscles, allowing them to contract and produce movement. When these signals are disrupted, certain parts of the body cannot move. Paralysis may be temporary, such as in Bell’s palsy, where facial muscles are affected and recovery is possible, or it may be permanent, resulting in a lasting loss of muscle control. Paralysis can affect any part of the body and may be partial (paresis), where some movement is possible, or complete, where there is no muscle control at all.
Paralysis is also classified based on how muscles are affected and where the nervous system injury occurs. Flaccid paralysis causes muscles to become weak, loose, and shrink over time, while spastic paralysis leads to muscle stiffness, spasms, and involuntary movements. In some cases, paralysis is localized and affects only a small area such as the face, hands, feet, or vocal cords. Because the nervous system controls communication between the brain and muscles, damage to this system prevents messages from reaching the muscles, leading to paralysis and loss of movement.