Spasticity is a condition caused by damage to the nerve pathways that control muscle movement. It causes muscles to become overly excited, either contracting and not allowing them to relax (called hypertonicity). It may also cause repetitive, rapid contractions (called clonus), deep-tendon reflexes, uncontrollable leg-crossing (scissoring), and fixed joints (contractures).
It is usually associated with damage to or abnormal development of the central nervous system by cerebral palsy, multiple sclerosis, spinal cord injury, brain trauma, or stroke. Or it may be caused by amyotrophic lateral sclerosis, hereditary spastic paraplegias, and metabolic diseases such as adrenoleukodystrophy, phenylketonuria, and Krabbe disease.
Treatment may include the use of baclofen, diazepam, tizanidine, or clonazepam. A physical therapist may help with muscle stretching and range of motion exercises. As appropriate, targeted injections of botulinum toxin may also be administered.