Spasticity is a condition in which certain muscles are continuously tight or stiff. This problem may interfere with movement, speech, and the ability to walk normally.

Spasticity is usually caused by damage to the portion of the brain or spinal cord that controls voluntary movement. It may occur in association with spinal cord injury; certain diseases, such as multiple sclerosis or cerebral palsy; damage to the brain; or metabolic diseases such as amyotrophic lateral sclerosis (Lou Gehrig's disease).

Symptoms may include:

• Increased muscle tone (hypertonicity).
• A series of rapid muscle contractions (clonus).
• Exaggerated deep tendon reflexes.
• Muscle spasms.
• Scissoring (crossing the legs without meaning to).
• Lack of flexibility from fixed joints.

Spasticity can range from slight muscle stiffness, to severe, painful, uncontrollable muscle spasms that interfere with daily activities.

Treatment usually includes physical therapy. This therapy involves exercises to help prevent muscles from becoming smaller or shorter. Treatment may also include prescription medications, such as baclofen, diazepam, tizanidine or clonazepam. Surgery is sometimes used for severe cases.