Quantitative Evaluation of Passive Muscle Stiffness in Chronic Stroke.

The study included only a small group of people with chronic stroke and a small control group, so the patterns may not apply broadly. Participants were recruited as a convenience sample from one rehabilitation clinic, so they may not represent all people with chronic stroke. Only people in the chronic phase after stroke were studied, so earlier changes in muscle stiffness were not captured. Repeated elbow extensions may have conditioned the tissues, although rest periods were used and the measures did not change appreciably. The ultrasound probe may not have sampled exactly the same muscle location as the elbow moved, because tissue can slide under the skin. EMG was used only to confirm relaxation, not to measure muscle activation, so small amounts of activity could have been missed. Many reliability estimates had wide confidence intervals, so the precision of the stiffness measures was limited.

The paper is listed as supported by NIH extramural research funding. No author conflicts or sponsor role are given in the supplied text.

Do not use these ultrasound stiffness patterns to diagnose spasticity or choose treatment. The study was small and exploratory, and it did not test any intervention.