Spasticity : Spasticity is a feature of altered skeletal muscle performance in muscle tone involving hypertonia; it is also referred to as an unusual "tightness", stiffness, or "pull" of muscles. The cause of spasticity is not really known, but there are several theories. In general, spasticity develops when an imbalance occurs in the excitatory and inhibitory input to a motor neurons caused by damage to the spinal cord and/or central nervous system. The damage causes a change in the balance of signals between the nervous system and the muscles, leading to increased excitability in the muscles. Spasticity is found in conditions where the brain and/or spinal cord are damaged or fail to develop normally; these include cerebral palsy, multiple sclerosis, spinal cord injury and acquired brain injury including stroke. Damage to the CNS as a result of stroke or spinal cord injury, alter of peripheral nerves in the affected region.