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Movement-contingent electrotactile feedback improves tactile sensitivity and sensory recovery after stroke: a randomized preregistered and controlled trial
Background
Somatosensory deficits affect most persons with stroke yet remain underdiagnosed and undertreated. Closed‑loop movement‑contingent sensory feedback may provide a scalable way to drive user‑dependent plasticity, improving hand sensation and the quality of life after stroke.
Methods
In this pilot randomized controlled trial, 20 adults in the recovery stage after ischemic or hemorrhagic stroke (≥ 1 month post‑onset) with impaired upper‑limb somatosensation were randomly allocated to an experimental group or control group. All participants continued standard physician-prescribed rehabilitation. Only the experimental group received a planned 10 sessions of an Active Touch Paradigm over 2 weeks (60 trials/session, 15–30 min; 9/10 completed all 10 sessions and 1 completed 8 because of earlier self-requested discharge from inpatient care); the control group did not receive a time-matched additional therapy dose. During training, participants used the affected index finger to scan pairs of invisible virtual textures on a tablet screen; each crossing of a virtual line triggered a single electrotactile pulse to the dorsum of the same finger, creating movement‑contingent electrotactile feedback. The primary outcome measure was tactile detection threshold at the trained index fingertip (Semmes–Weinstein monofilaments, evaluator size). The secondary outcome measures were tactile thresholds at the thumb and middle fingers of the affected hand, thresholds in a subset of ipsilateral digits, and upper‑limb motor and functional measures. The outcomes were assessed pre‑ and post‑intervention. Outcome assessors were not blinded.
Results
A significant Time × Group interaction was found for the affected index‑finger threshold (F(1,18) = 6.90, p = 0.017, partial η²=0.28). The experimental group improved from 5.34 ± 1.10 to 4.79 ± 1.30 evaluator size, whereas the control group changed from 4.82 ± 1.16 to 4.69 ± 1.15. No significant interactions were observed for thumb or middle‑finger thresholds, although a trend emerged for the thumb. Using North Coast sensory grades, 7/10 experimental participants versus 2/10 controls improved by at least one grade at the trained digit. Both groups improved over time on Fugl‑Meyer and Action Research Arm Test scores.
Conclusions
A brief, tablet‑based, movement‑contingent electrotactile training protocol selectively improved tactile sensitivity at a single trained digit after stroke without additional benefit on broader motor outcomes. The Active Touch Paradigm appears feasible, clinically practical, and specifically effective for post‑stroke tactile rehabilitation, warranting larger mechanistic trials and integration with task‑oriented upper‑limb training.
Trial registration
ClinicalTrials.gov. NCT06962397 (retrospectively registered on 30 April 2025).