Spasticity is a condition in which there is an abnormal increase in muscle tone or stiffness of muscle, which might interfere with movement, speech, or be associated with discomfort or pain. Spasticity is a term that is often used interchangeably with hypertonia. Hypertonia is a condition in which there is too much muscle tone so that arms or legs, for example, are stiff and difficult to move. Spasticity, however, is a particular type of hypertonia in which the muscles' tightness are increased by movement. In this type, patients usually have exaggerated reflex responses.
Spasticity is usually caused by damage to nerve pathways within the brain or spinal cord that control muscle movement. It may occur in association with spinal cord injury, multiple sclerosis, cerebral palsy, stroke, brain or head trauma, amyotrophic lateral sclerosis, hereditary spastic paraplegias, and metabolic diseases such as adrenoleukodystrophy, phenylketonuria, and Krabbe disease. Symptoms may include hypertonicity (increased muscle tone), clonus (a series of rapid muscle contractions), exaggerated deep tendon reflexes, muscle spasms, scissoring (involuntary crossing of the legs), and fixed joints (contractures). The degree of spasticity varies from mild muscle stiffness to severe, painful, and uncontrollable muscle spasms. Spasticity can interfere with rehabilitation in patients with certain disorders, and often interferes with daily activities. If the increased muscle tightness is severe, it can cause a joint to become "frozen," which doctors call a joint contracture.
Pediatric physiatrists specialize in the treatment of spasticity. Treatment may include such muscle-relaxing drugs such as baclofen, diazepam, or clonazepam. All of these drugs can be taken by mouth or via a g-tube, but baclofen may also be injected directly into the cerebrospinal fluid through an implanted pump. Physiatrists also use Botulinum to relieve spasticity and hypertonia in a specific area of the body because its effects are local, not body-wide. Targeted injection of botulinum toxin into muscles with the most tone can help to selectively and temporarily weaken these muscles to improve range of motion and function.
People with spasticity and hypertonia should try to preserve as much movement as possibly by exercising within their limits. Physical therapy regimens may include muscle stretching and range of motion exercises to help prevent shrinkage or shortening of muscles and to reduce the severity of symptoms.Surgery may be recommended for tendon release or to sever the nerve-muscle pathway.
NIH: National Institute of Neurological Disorders and Stroke