When muscles contract, stiffen, or spasm involuntarily, the condition is referred to as “spasticity.” As a result of these sometimes uncomfortable and/or painful symptoms, affected individuals may find it difficult to walk, move, or talk. The problem rests with damage or interruption of the nerve pulses that control muscle movement, which can be caused by conditions such as spinal cord injury, brain injury, amyotrophic lateral sclerosis (ALS), or multiple sclerosis (MS). In the case of MS, spasticity may help those with weak legs gain the rigidity needed to help them walk. In these instances, the goal of physical therapy is to relieve pain while maintaining necessary rigidity.