How can dystonia be distinguished from spasticity in CP?

• A. Dystonia is always localized to the limbs
• B. Dystonia is characterized by fixed postures with no movement component
• C. Dystonia involves sustained or intermittent involuntary twisting movements; spasticity is velocity-dependent resistance to passive movement
• D. Spasticity is a permanent increase in muscle tone independent of movement

Answer: (C)

Dystonia and spasticity are driven by different motor abnormalities, which is why this distinction matters in CP assessment. Dystonia presents as involuntary twisting movements that can be sustained or intermittent, often producing abnormal postures and fluctuation with activity, attention, or emotional state. Spasticity, by contrast, is a velocity-dependent resistance to passive movement caused by hyperexcitable stretch reflexes; the faster you move the limb, the greater the resistance.

So the best statement captures that contrast: dystonia involves sustained or intermittent involuntary twisting movements, while spasticity is a velocity-dependent resistance to passive movement. The other options mischaracterize dystonia as only a fixed postural issue or limit it to the limbs, and they describe spasticity as a permanent, movement-independent increase in tone, which isn’t accurate.