Overview of Spasticity

The most common causes of spasticity are lack of oxygen to the brain before, during, or after birth (cerebral palsy); physical trauma (brain or spinal cord injury); blockage of or bleeding from a blood vessel in the brain (stroke); multiple sclerosis (MS); or infection of the brain (encephalitis) or the covering of the brain and spinal cord (meningitis). When the damage that causes the eventual spasticity first occurs, the muscles are usually flaccid before they become spastic. Spasticity may not be present all the time—it may be related to a trigger, or stimulus, such as pain, pressure sores, a urinary tract infection, ingrown toenails, tight clothing, or constipation.

Spasticity may be painful, especially if it pulls joints into abnormal positions and or prevents a normal movement of the joints. Spasticity may range from slight muscle stiffness to permanent shortening of the muscle. When the muscle is permanently shortened, the joint becomes misshapen. This is called a contracture and is one of the most significant consequences of spasticity. Another closely related problem with muscles in many people who have spasticity is clonus, or rapid repeated muscle spasms.

While spasticity may affect any muscle group, there are some common patterns. When spasticity affects one or both arms, flexed (bent) elbow, flexed wrist, and clenched fist may result. These can all affect the person's ability to dress, eat, or write or may interfere with balance, thereby causing difficulties with walking. Spasticity of the legs can cause flexed hip, adducted (or scissoring) thigh, stiff knee, flexed knee, equinovarus foot, and hyperextended great toe (which is also called the hitchhiker's toe). Spasticity of one or both legs may interfere with the ability to walk, position in bed, sit, transfer, or stand.

	Epidemiology