Paralysis is the loss of the ability to move one or more muscles, usually caused by problems between the nerves and spinal cord that the brain uses to control muscle function. Paralysis can be complete or partial, and be in one specific area of the body or widespread. The most common causes of paralysis are stroke, head injury, spinal cord injury, and multiple sclerosis. Cerebral palsy, Bell’s palsy, and Guillain-Barre syndrome may also be causes of paralysis. Paralysis is classified into several types, including: monoplegia, where one limb is paralyzed, hemiplegia, where the arm and leg on one side of the body are paralyzed, paraplegia, where both legs and some of the lower body are paralyzed, and tetraplegia or quadriplegia, where both arms and legs are paralyzed.