Spasticity is tightness or stiffness of muscles.
GABA is a natural substance in the body that is believed to play a role in allowing muscles to relax. Painful spasms may be triggered by something as minor as a simple movement of the arm or leg, skin irritation or a full bladder. Spasticity results from a disorder of or injury to the central nervous system. Complex messages continuously move back and forth between the muscles and the brain, using the spinal cord as a pathway. Normally, muscle groups in the nervous system work together so that when one is flexed, its opposing muscle is relaxed.