Which statement about spasticity is correct?

• A. It is a voluntary increase in muscle strength.
• B. It is a condition characterized by muscle stiffness and involuntary contractions, often associated with neurological injury.
• C. It is unrelated to the nervous system.
• D. It only occurs in healthy individuals.

Answer: (B)

Spasticity is a velocity-dependent increase in muscle tone with involuntary contractions caused by upper motor neuron damage in the central nervous system. This leads to stiffness and sudden, reflexive muscle activity, especially when a limb is moved quickly. It often follows neurological injuries such as stroke, spinal cord injury, traumatic brain injury, multiple sclerosis, or cerebral palsy. That combination—muscle stiffness and involuntary contractions tied to CNS injury—fits the statement best. It is not a voluntary increase in strength; spasticity reflects altered neuromuscular control and reflex hyperexcitability. It relates to the nervous system and does not occur in healthy individuals.