The Ashworth Scale evaluates muscle tone by measuring resistance during passive muscle stretching. The nurse or healthcare provider moves the patient's limb at a consistent speed through its range of motion and grades the resistance encountered on a scale from 0 to 4:
- 0: No increase in muscle tone - 1: Slight increase in muscle tone, manifested by a catch and release or minimal resistance at the end of the range of motion - 1+: Slight increase in muscle tone, manifested by a catch followed by minimal resistance throughout the remainder of the range of motion - 2: More marked increase in muscle tone through most of the range of motion, but affected part(s) easily moved - 3: Considerable increase in muscle tone, making passive movement difficult - 4: Affected part(s) rigid in flexion or extension
