paralysis

Paralysis is the loss of voluntary muscle function in a part of the body, usually caused by damage to the nervous system or muscles. It results in an inability to move the affected muscles or to control them. Paralysis is distinct from general weakness or incoordination.

Classification can be by extent (localized or generalized), duration (acute or chronic), and origin (central or peripheral). Central paralysis involves motor pathways in the brain or spinal cord, while peripheral paralysis involves nerves or the neuromuscular junction. Common types include spastic paralysis, associated with upper motor neuron injury and increased muscle tone, and flaccid paralysis, associated with lower motor neuron injury and reduced tone. The terms hemiplegia, paraplegia, and quadriplegia describe paralysis in specific regions of the body.

Causes are diverse and include stroke, spinal cord injury, brain or spinal diseases (such as multiple sclerosis or amyotrophic lateral sclerosis), infections (for example Guillain-Barré syndrome), poliomyelitis, peripheral neuropathies, nerve compression, trauma, tumors, and congenital conditions. Some forms are temporary, but others may be permanent.

Symptoms and diagnosis depend on the type and location but commonly include inability to move the affected muscles, possible sensory changes, muscle atrophy, and altered reflexes. Diagnostic evaluation includes a neurological exam, imaging such as MRI or CT, nerve conduction studies and electromyography, blood tests, and sometimes lumbar puncture to identify underlying causes.

Treatment and prognosis focus on the underlying cause and supportive care. This may involve emergency stabilization, surgery, immunotherapies for inflammatory or autoimmune conditions, antimicrobial therapy when infection is present, and extensive rehabilitation with physical and occupational therapy. Spasticity and pain management may be needed. Prognosis varies widely, ranging from substantial recovery in some conditions to permanent disability in others.