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Quantitative measures of spasticity in post-stroke patients
F Pisano1, G Miscio, C Del Conte
1Department of Neurology, Unit of Neurophysiology, 'Salvatore Maugeri' Foundation, IRCCS, Rehabilitation Institute 28010 (NO), Veruno, Italy. neufis.veruno@fsm.it
Summary
This study introduces a biomechanical technique for objectively measuring muscle tone in post-stroke patients. It provides quantitative muscle stiffness indices that correlate with clinical spasticity scores, aiding treatment monitoring.
Area of Science:
- Neuroscience
- Biomedical Engineering
- Rehabilitation Medicine
Background:
- Stroke frequently causes increased muscle tone (spasticity), impacting motor function.
- Objective quantification of muscle tone is crucial for effective rehabilitation and treatment monitoring.
- Existing clinical scales for spasticity lack objective biomechanical correlates.
Purpose of the Study:
- To quantitatively evaluate muscle tone in post-stroke patients using a novel biomechanical approach.
- To correlate biomechanical indices of muscle tone with established clinical scales and neurophysiological measures.
- To characterize the passive and neural components contributing to muscle tone in spasticity.
Main Methods:
- Utilized a torque motor to apply mechanical stretches to wrist flexor muscles in 53 post-stroke patients.
- Assessed patients using the modified Ashworth scale for spasticity and the Medical Research Council score for strength.
- Measured neurophysiological parameters including Hoffmann reflex (H) latency, Hmax/Mmax ratio, and stretch reflex (SR) characteristics, alongside passive (ISI) and total (TSI) stiffness indices.
Main Results:
- Biomechanical indices like Hmax/Mmax ratio, SR area, ISI, and TSI were significantly elevated in post-stroke patients.
- Stretch reflex threshold speed (SRTS) was significantly reduced in the patient group.
- Total stiffness index (TSI), SRTS, and SR area demonstrated strong correlations with the Ashworth spasticity score.
Conclusions:
- The developed EMG-biomechanical technique offers objective, quantitative assessment of muscle tone and stiffness in post-stroke patients.
- The derived quantitative indices are suitable for monitoring treatment-induced changes in muscle tone.
- The apparatus shows promise for characterizing neural contributions to stiffness, though isolating passive components was challenging due to tonic EMG activity in spastic patients.