Cortical neuromodulation by vibration-induced illusion of movement is observed in older individuals, but not in individuals with acute stroke: a cross-sectional fNIRS study.

The stroke group had only 23 participants, and the authors' own power calculation showed the study had only about one-fifth of the power needed to detect the small effect they observed, meaning a real but modest effect could easily be missed. Only the left paretic arm was tested in the stroke group, so the finding cannot be generalised to the non-affected side or to left-hemisphere strokes. Spasticity was not measured, and the authors note it can interfere with the perception of the illusion and may have contributed to the null finding. Cognitive impairment and aphasia were not quantified in the stroke group, which could affect how participants reported the illusion. This is a single time-point, single-site study; it cannot tell you whether the absent response is permanent or simply a feature of the first two weeks. The efficiency ratio used to compare groups is a novel metric without established clinical norms, so its interpretation remains uncertain.

Funded by the Association Nationale de la Recherche et de la Technologie (a French public research body). No industry sponsor, device manufacturer, or treatment vendor is named. The vibrator used (Vibramoov PHYSIO, Techno Concept) is a commercial product, but the company is not listed as a funder or co-author.

Do not read the absent cortical activation in the stroke group as proof that tendinous vibration is useless in acute stroke. The authors themselves note the study had very low statistical power for the stroke group, that spasticity was not controlled for, and that the efficiency ratio was comparable to older adults. All of which mean the null finding may reflect measurement limits rather than a true absence of any physiological effect.