Stretch reflex excitability in contralateral limbs of stroke survivors is higher than in matched controls.
Taimoor Afzal, Matthieu K Chardon, William Z Rymer and 1 others
PMID 31806032WHAT IT FOUND
Stroke survivors showed exaggerated stretch reflexes not just in the spastic arm but also in the non-spastic arm.
The non-spastic arm required less tendon indentation to trigger a reflex than healthy controls, suggesting bilateral nervous system changes after stroke.
Key findings
01The stretch reflex threshold on the non-spastic side of stroke survivors was significantly lower than in healthy controls.
02Reflex thresholds were lowest on the spastic side, intermediate on the non-spastic side, and highest in controls.
03There was a positive correlation between reflex thresholds on the spastic and non-spastic sides, suggesting linked excitability.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
Read the rest of this summary
You get three full summaries a month, free, and we do not ask for a card. Search, the TL;DRs and your library stay unlimited either way.
What it does not show
The sample size was very small (9 stroke survivors, 10 controls). Reflex thresholds could not be detected in all subjects on all muscles; for those missing data, the maximum tolerated indentation was used as a proxy, which underestimates the true threshold. The study measured reflex excitability, not functional movement, pain, or spasticity severity beyond the Modified Ashworth Scale inclusion criterion. Controls were only tested on the dominant arm, while stroke survivors were tested on both, which may introduce side-specific differences not accounted for. The mechanical tapper setup is highly specialized and not available in standard clinical settings.
Declared interests
Funded by the National Institute of Health (N.I.H.). No other conflicts declared.
The easy way to misread this
Do not interpret this as evidence that the non-spastic arm is clinically impaired or spastic. The study shows physiological hyperexcitability, but the authors note that spasticity is 'diagnosed routinely only on the affected side' and this test requires specialized equipment not used in clinical practice.