Which feature is most characteristic of spasticity?

Which feature is most characteristic of spasticity?

• A. End feel is smooth and uniform
• B. Velocity-dependent increase in muscle tone
• C. Tone remains constant regardless of movement speed
• D. Occurs only with lower motor neuron lesions

Answer: (B)

Spasticity is driven by hyperexcitable stretch reflexes from an upper motor neuron lesion, so the key feature is that muscle tone increases with the speed of the movement. In practice, the faster you passively move the limb, the more resistance you feel, while slower movements produce less resistance. This velocity-dependent pattern helps distinguish it from other types of tone changes, such as rigidity, where tone is not tied to movement speed, or from conditions tied to lower motor neuron pathology, which typically cause decreased tone. The end feel in spasticity is not a smooth, uniform resistance; it often has a catch or abrupt increase in resistance that may release with continued stretch.

Spasticity is driven by hyperexcitable stretch reflexes from an upper motor neuron lesion, so the key feature is that muscle tone increases with the speed of the movement. In practice, the faster you passively move the limb, the more resistance you feel, while slower movements produce less resistance. This velocity-dependent pattern helps distinguish it from other types of tone changes, such as rigidity, where tone is not tied to movement speed, or from conditions tied to lower motor neuron pathology, which typically cause decreased tone. The end feel in spasticity is not a smooth, uniform resistance; it often has a catch or abrupt increase in resistance that may release with continued stretch.