Cortical mapping of real-time ultrasound-imaging visual feedback for ankle dorsiflexion in patients after stroke: a fNIRS study.

The study was severely underpowered. A post-hoc analysis showed only 11% statistical power for the primary outcome, meaning the sample size was far too small to reliably detect real differences. It was a cross-sectional pilot, not a longitudinal trial. It shows what happens in the brain during one session of feedback, not whether this leads to actual motor recovery over weeks or months. Motor output was only partially controlled. While the number of repetitions was counted, the speed, range, and force of the ankle movement were not measured, so differences in brain activity could be due to how hard the participants worked rather than the feedback itself. The stroke group had specific inclusion criteria (subcortical lesions only, no severe spasticity), so results may not apply to patients with cortical strokes or significant spasticity.

The authors declared no conflicts of interest. The work was funded by grants from West China Hospital, Sichuan University, the Sichuan Science and Technology Program, the National Key R&D Program of China, the Hong Kong Research Grants Council, and the Research Institute for Smart Ageing.

Do not interpret the changes in brain connectivity or deoxygenated blood signals as evidence that ultrasound feedback improves physical function or recovery. The study was underpowered, did not measure clinical outcomes like walking ability, and the primary neural measure (oxygenated hemoglobin) showed no benefit from the feedback.