Spasticity is a condition in which muscles stiffen or tighten, preventing normal fluid movement. The muscles remain contracted and resist being stretched, thus affecting movement, speech and gait.

Spasticity is generally caused by damage or disruption to the area of the brain and spinal cord that are responsible for controlling muscle and stretch reflexes. These disruptions can be due to an imbalance in the inhibitory and excitatory signals sent to the muscles, causing them to lock in place. Spasticity can be harmful to growing children as it can affect muscles and joints. People with brain injury, spinal cord injury, cerebral palsy or multiple sclerosis can have varying degrees of spasticity.

Symptoms of spasticity can vary from being mild stiffness or tightening of muscles to painful and uncontrollable spasms. Pain or tightness in joints is also common in spasticity.