Spasticity can be described as involuntary muscle stiffness. It is a common symptom of neurological disease, and can range from mild to severe and change over time, often from day to day or hour to hour. Other associated features can include spasms, pain, weakness and clonus. Spasticity is not always detrimental, as some people use the stiffness in their muscles to help them stand, transfer or walk. However, prolonged spasticity may result in shortening of the muscle, which further increases the stiffness, limits the range of movement of the limb and is not always responsive to drug treatments.