Spasticity is a motor disorder characterized by a velocity-dependent increase in tonic muscle tone with exaggerated tendon jerks, resulting from hyperexcitability of the tonic stretch reflex. (See Pathophysiology) It is a component of the upper motor neuron syndrome, is characterized by increasing resistance to more rapid passive movements,1 and results from interruption of inhibitory descending spinal motor control. Signs associated with spasticity include:2

• clasp-knife phenomenon (a sudden reduction in tone as the limb is flexed or extended passively, when resistance dissipates during stretch)
• weakness
• increased muscle tone
• impaired dexterity and coordination
• hyperreflexia
• extensor plantar responses
• spontaneous muscle spasms and contractures

Patients with spasticity experience increased muscle tone in the setting of noxious stimuli such as:

• infection
• urolithiasis
• bladder or bowel retention
• decubitus ulcers
• tight or ill-fitting clothing or orthotics

Spasticity complicates neurologic disorders such as cerebral palsy, spinal cord injury, stroke, multiple sclerosis (MS), and degenerative disorders. Its symptoms can greatly interfere with a patient’s functional capacity and quality of life.

Practitioners need to understand the mechanisms of various therapies in order to develop an effective, individualized regimen. Most patients experience symptomatic improvement with physiotherapy in combination with one or more antispasticity agents. Patients whose condition is refractory to these treatment options may respond to a variety of neurosurgical procedures to relieve severe spasticity.

• Treatment: Developing an individualized regimen
• Pharmacotherapy

Adapted from: Bassi V, Kita M, Feldman DS, and Devinsky O. Spasticity. In: Devinsky O and Westbrook LE, eds. Epilepsy and Developmental Disabilities. Boston: Butterworth-Heinemann; 2001;231–247.
With permission from Elsevier (www.elsevier.com).
Reviewed and revised May 2004 by Steven C. Schachter, MD, epilepsy.com Editorial Board.