Kilohertz Transcranial Magnetic Perturbation (kTMP) for Upper Extremity Motor Recovery After Stroke: A Nonrandomized Pilot Trial

Importance: Upper extremity impairment is a leading cause of post-stroke disability, yet clinically approved neuromodulation therapies are currently limited by the risks and costs of surgical implantation. There is an unmet need for non-invasive brain stimulation. Objective: To evaluate the feasibility, safety, and preliminary clinical efficacy of a novel form of non-invasive brain stimulation, kilohertz transcranial magnetic perturbation (kTMP), for upper limb motor recovery after stroke. Design: A single-center, open-label trial was conducted between September 2025 and April 2026 and comprised a 4-week standard-of-care baseline period, 4 weeks of active treatment with kTMP combined with motor training, and a 4-week follow-up. Setting: Academic research center. Participants: Seven individuals with chronic stroke and upper extremity motor deficits. Intervention: Four weeks of kTMP (3 sessions/week), a brain stimulation approach using magnetic induction to generate subthreshold electric fields, paired with motor tasks. Main Outcomes: Change in Fugl-Meyer Assessment for Upper Extremity (FMA-UE) scores across study periods (standard-of-care baseline, active treatment, follow up). Secondary outcomes included measures of movement smoothness (Spectral Arc Length, SPARC) and fragmentation (mean velocity peak count), and intervention tolerability ratings. Results: Across 7 participants (mean [SD] age, 57.4 [8.7] years; 4 males; mean [SD] time poststroke, 3.5 [2.1] years). No device-related adverse events occurred, and the intervention was well-tolerated (participants rated sensation intensity at an average of less than 0.5 on a 0-10 scale). FMA-UE scores remained stable during the baseline period (mean change, +0.14 points; 95% CI, -1.21 to 1.50; adjusted P = .98), increased significantly following the kTMP-intervention (mean change, +7.00 points; 95% CI, 5.31 to 8.69; adjusted P = .047), and were sustained at the 4-week follow-up (mean change, -1.33 points; 95% CI, -2.42 to -.25 points; adjusted P = .13). Movement smoothness improved significantly within 1 week of kTMP onset (mean change, 1.48 points; 95% CI, .49 to 2.47; adjusted P = .03); movement fragmentation showed a similar but nonsignificant trend. Conclusions and Relevance: This pilot trial provides preliminary evidence that kTMP combined with motor tasks is safe, feasible, and may support upper extremity recovery. These pilot data warrant large, randomized controlled trials to evaluate efficacy in support of poststroke motor recovery. Trial Registration: ClinicalTrials.gov Identifier: NCT06317194