Stiffness, Spasticity and Spasms It is very common for people with MS to experience “tightness” or stiffness in their muscles.  Some people notice this stiffness more in the morning before their muscles warm up.  Stiffness may be caused by a decrease in flexibility when activity levels decrease, or it may be due to spasticity, a neurological effect.  If one becomes inactive due to extreme fatigue, a sedentary lifestyle, or pain related to limited movement, stiffness may occur. MS-related spasticity occurs when there is an injury to the central nervous system.  The injury results in abnormal messages being sent to the muscles which creates an increase in “tone” or muscle tightness.  Everyone needs some muscle tone to maintain an erect posture and conduct daily activities; spasticity occurs when people have abnormally high tone which may interfere with movement.  Generally the legs are more affected by spasticity than the arms or other muscles, and sometimes patients experience one side of their body being more affected than the other.   Spasticity is often triggered by rapid movements and can be quite painful.  Spasticity can also create difficulties with moving or walking and can contribute to foot drop, where an individual cannot flex the foot sufficiently to clear the toe while walking.   Severe untreated spasticity can lead to contractures (restriction of movement in joints), skin breakdown, and pain.  Therefore, spasticity should be treated aggressively.  Spasms are strong muscle contractions that tend to be painful although brief.