The Human Cortical Motor Map in Post-Stroke Hemiparesis in the Presence of Treatment-Related Clinically Important Recovery

Objectives: To determine if intervention-related clinical improvement in post-stroke hemiparesis is associated with enlarged primary motor cortex representation. Methods: Data were analyzed from a single site subset of the NICHE trial. Transcranial magnetic stimulation (TMS) motor mapping was performed in 23 participants (3-12 months post-stroke, 10 female, 40-88 yrs, baseline Fugl-Meyer Upper Extremity (FM-UE) range 13-58) before and after intervention. TMS motor maps were acquired for the extensor digitorum communis muscle (EDC) bilaterally, at 110% resting motor threshold (RMT). Results: Improvement on the primary outcome measure (FM-UE) was statistically and clinically significant (mean pre= 38(±15), post= 45(±16), p <0.001; n=23). Significant improvement was also observed on secondary impairment and activity outcome measures (p<0.05). Ipsilesional hemisphere RMT and map volume (MV) remained unchanged (RMT pre = 42(±13), post = 41(±11), p=0.60; MV pre =78.0(±71.4) mV*mm2, post =109.5(±139.1) mV*mm2, p=0.36). The magnitude of clinical benefit was unrelated to difference in map characteristics from pre to post (Spearman′s rho= 0.06, p=0.79). Conclusions: Intervention-related clinical improvement of the upper limb 3-12 months following stroke, was not associated with change in motor cortex excitability or increase in motor maps. Clinical improvements may not solely rely on consistent changes in the cortical motor representation. ### Competing Interest Statement All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: support from the Nexstim Corporation for the submitted work; DJE has received research grants and travel support from the Chernowitz Medical Research Foundation, DJE is on the Scientific Advisory Board for Center for Mesoscale Mapping (NIH-P41), MGH/HST Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital; no other relationships or activities that could appear to have influenced the submitted work. ### Clinical Trial This is a single-center substudy analyzing data collected for a clinical trial [NCT02089464][1] ### Funding Statement This study was supported by a grant from the Nexstim Corporation, Helsinki, Finland, and The Chernowitz Medical Research Foundation, Denver, USA. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The Institutional Review Board of the Burke Rehabilitation Hospital gave ethical approval for this work. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT02089464&atom=%2Fmedrxiv%2Fearly%2F2024%2F07%2F03%2F2024.07.01.24309575.atom