When muscles lose their ability to move, the medical term for this is paralysis. Often this loss of movement will be accompanied by a loss of sensation as well.
Paralysis may be a temporary condition, or it may turn out to be permanent. It can affect only one small area of the body, or it can be widespread.
Paralysis on one side of the body is known as unilateral. Paralysis on both sides is bilateral.
Paralysis in the legs and lower half of the body is known as paraplegia. When paralysis is in both arms and legs, it is called quadriplegia.
Global paralysis is weakness throughout the body, as can occur with a stroke. Weakness on just one side of the body is called hemiplegia.
Physical trauma is a common cause of paralysis. This would encompass things like accidents, blocked blood vessels, infection, poisoning and the presence of tumors.
It would also include injuries such as a broken back or broken neck, and nerve damage.
Certain diseases can be the cause of paralysis. Bell's palsy is noted for localized paralysis (paralysis in a small area). Usually just one side of the face will become paralyzed due to inflammation in the facial nerve.
Guillain-Barre syndrome, an autoimmune disorder, causes the body's immune system to attack its own nerve fibers, initially in the hands and feet.
Myasthenia gravis is also an autoimmune disorder in which the muscles do not properly receive messages being sent from the brain through the central nervous system for muscle movement.
Progressive disorders like muscular dystrophy or multiple sclerosis damage the muscles or the central nervous system over time, and the paralysis may start as muscle weakness, but will continue to worsen.
Poliomyelitis and stroke will bring on paralysis quickly. Spinal cord paralysis can cause quadriplegia and loss of sensation immediately.
Messaging between the brain and the affected part of the body is disrupted at the area of injury, and all movement stops. The nerves above the area of injury will still continue to function as before.