Reliability and diagnostic accuracy of corrected slack angle derived from 2D-SWE in quantitating muscle spasticity of stroke patients.
Junyan Cao, Yang Xiao, Weihong Qiu and 6 others
PMID 35120556WHAT IT FOUND
In 20 stroke patients, a corrected ultrasound slack angle tracked spasticity severity, and cutoffs classified severe cases.
It is not yet a validated clinical test.
Key findings
01The corrected slack angle was significantly correlated with modified Ashworth scale scores.
02For severe spasticity (MAS ≥ 3), the corrected angle had the best classification performance, with sensitivity 100% and specificity 93.33%.
03Both intraobserver (0.791) and interobserver (0.751) reliability of slack angle were good.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
Thirty-eight eligible patients were enrolled, 16 were ruled out, and 2 failed measurement, leaving 20 patients and 20 controls analysed. MAS 4 patients were excluded because the ankle was rigid, so very severe spasticity was not represented. Reliability of slack angle was analysed in only 13 participants. Only the thickest part of the medial gastrocnemius was measured, and other triceps surae muscles were not included. Self-correction could not completely exclude non-neural contributors because bilateral structural changes were not synchronous after stroke. The BoNT-A observation included five patients and did not test statistical significance. No standard protocol exists for this measurement, and the ankle was moved at one constant velocity.
Declared interests
Funding was provided by the Medical Scientific Research Foundation of Guangdong Province, China, the National Natural Science Foundation of China, and the Research & Development Program in Key Areas of Guangdong Province. The supplied text does not state author conflicts of interest.
The easy way to misread this
Do not conclude that corrected slack angle is a validated clinical test or that BoNT-A injection was proven effective. The study had only 20 stroke patients, and the injection change was observed in five patients without statistical testing.