Paralysis is a loss of nerve function or muscle power resulting in an inability to move. When nerve cells in the brain or other parts of the body are damaged by injury or disease, the body parts controlled by those nerve or brain cells do not function.

The damage may cause mild or severe loss of function and may be temporary or permanent. The degree of paralysis depends on:

• Which nerve cells are damaged and, when paralysis is caused by brain damage, how much of the brain is involved.
• How quickly the blood supply returns to the area, how quickly pressure is taken off the nerve, or how soon the disease causing the problem is corrected.