spasticity
Pronunciation: spas-TIS-ih-tee
A motor disorder characterized by velocity-dependent increase in muscle tone and exaggerated tendon reflexes due to upper motor neuron lesions.
Full Definition
Spasticity is a component of upper motor neuron syndrome characterized by increased muscle tone that is velocity-dependent, meaning resistance to passive movement increases with the speed of stretching. It results from damage to descending motor pathways, particularly the corticospinal tract, leading to disinhibition of spinal reflexes. Clinical features include exaggerated deep tendon reflexes, clonus, and a 'clasp-knife' phenomenon where initial resistance to passive movement suddenly decreases. Spasticity differs from rigidity, which is velocity-independent. Common causes include stroke, spinal cord injury, multiple sclerosis, and cerebral palsy. Spasticity can significantly impact function and quality of life, requiring targeted management strategies.
Usage
Usage note: Grade severity using standardized scales; distinguish from rigidity and dystonia.
In Context
- "Moderate spasticity was present in the left lower extremity following right hemispheric stroke." — Rehabilitation assessment
- "The patient's spasticity improved with antispasmodic medication and physical therapy." — Treatment note