Spasticity

Spasticity is a velocity-dependent increase in muscle tone caused by damage to the brain or spinal cord, making muscles stiff, tight and resistant to movement.

It results from a loss of the normal inhibitory control that the brain exerts over spinal reflexes and is seen in multiple sclerosis, spinal cord injury, stroke, cerebral palsy and traumatic brain injury. Affected limbs may feel rigid, jerk involuntarily, or lock in bent or extended positions, and painful spasms are common. Spasticity can interfere with walking, hygiene, sleep and comfort, though a degree of stiffness sometimes aids standing.

Clinicians grade it with scales such as the Modified Ashworth Scale, which rates resistance to passive movement, along with patient-reported numeric ratings and functional measures. Physical therapy, oral muscle relaxants, botulinum toxin injections and intrathecal baclofen are established approaches. Cannabinoids have been studied for spasticity in multiple sclerosis more than for any other symptom, with modest effects on patient-reported measures and no approved use in the United States.