Paralysis

Paralysis is the complete loss of muscle function for one or more muscle groups. Major causes are stroke, trauma, poliomyelitis, amyotrophic lateral sclerosis (ALS), botulism, spina bifida, multiple sclerosis, and Guillain-Barré syndrome. Paralysis is most often caused by damage to the nervous system or brain, especially the spinal cord. Paralysis often includes loss of feeling in the affected area.

Paralysis may be localized, or generalized, or it may follow a certain pattern. For example, localized paralysis occurs in Bell’s palsy where one side of the face may be paralysed due to inflammation of the facial nerve on that side. Patients with stroke may be weak throughout their body (global paralysis) or have hemiplegia (weakness on one side of the body) or other patterns of paralysis depending on the area of damage in the brain. Other patterns of paralysis arise due to different lesions and their sequelae. For example, lower spinal cord damage from a severe back injury may result in paraplegia, while an injury higher up on the spinal cord, such as a neck injury, can cause quadriplegia.

Most paralyses caused by nervous system damage are constant in nature; however, there are forms of periodic paralysis, including sleep paralysis, which are caused by other factors.

Poisons that interfere with nerve function, such as curare, can also cause paralysis.