Emerging Therapies for Spastic Movement Disorders

Spasticity develops as a result of CNS injury; however, secondary changes within the muscles and connective tissue also contribute to muscle stiffness. The hyaluronan hypothesis postulates that the accumulation of hyaluronan, a high molecular weight glycosaminoglycan which acts as a lubricant within the extracellular matrix of muscles, promotes the development of muscle stiffness. Intramuscular injections of the enzyme hyaluronidase, which hydrolyzes long-chained hyaluronan polymers to smaller polymers, was shown to reduce muscle stiffness and increase passive and active range of motion in patients with spasticity. These results provide preliminary evidence of the hyaluronan hypothesis and suggest an emerging therapy to reduce muscle stiffness using the enzyme hyaluronidase.