Vibration-induced illusion of movement is hindered by acute stroke but mostly by aging: a cross-sectional study

The proprioceptive and visual systems play a major role in daily tasks by providing continuous feedback to the central nervous system (CNS) for coordinating movements. However, it remains unclear to what extent alterations in the proprioceptive system and CNS affect vibration-induced illusion of movement (VIM) with age and after a stroke. To address this, 29 young (26 ± 7 years), 30 older (63 ± 8 years), and 26 stroke participants (68 ± 12 years) with left arm impairment, all right-handed, received triceps brachii tendon vibration with or without visual feedback of the vibrated arm (with/without vision), as it can modulate the illusion of movement. Vibrations were applied bilaterally in healthy participants and on the impaired left arm in stroke individuals. The illusion was quantified using the Standardized Kinesthetic Illusion Procedure (SKIP) ordinal scale, which evaluates the clearness and the direction of the movement, resulting in a total score on four. While young and older adults achieved higher scores without vision, acute stroke participants did not (Young_left: µ_{(without/with)} = 2.62/0.86, p < 0.001, Young_right: µ_{(without/with)} = 2.35/0.69, p < 0.001; Older_left: µ_{(without/with)} = 1.52/0.63, p < 0.001, Older_right: µ_{(without/with)} = 1.03/0.50, p < 0.01; Stroke: µ_{(without/with)} = 0.85/0.62, p = 0.23). Moreover, young participants reported a stronger illusion than both older and acute stroke participants, and older participants reported a stronger illusion than acute stroke participants. Altogether, these findings suggest that aging alters VIM response, with acute stroke exacerbating this impairment. Finally, in acute stroke participants, a significant negative correlation between age and SKIP total score without vision was observed, highlighting the considerable impact of aging even within a pathological condition.Clinical Trial registration: NCT06218563-2024-01-12.