Affiliations: Division of Physical Therapy, Department of Rehabilitation Medicine, School of Medicine, Emory University, Atlanta, GA, USA | Department of Physical Therapy, Faculty of Medicine, University of British Columbia Vancouver, BC, Canada
Note: [] Corresponding author: Michael R. Borich, Division of Physical Therapy, Department of Rehabilitation Medicine, Emory University School of Medicine, 1441 Clifton Rd NE, R228, Atlanta, Georgia 30322, United States. Tel.: +1 404 712 0612; Fax: +1 404 712 4130; E-mail: michael.borich@emory.edu
Abstract: Purpose: Rehabilitation interventions need to be optimized to maximize therapeutic effects and minimize stroke-related disability. However, a comprehensive understanding of the neural substrates underlying recovery is lacking. The purpose of this study was to investigate relationships between brain anatomy, physiology and hand motor function in individuals with chronic stroke. Methods: Transcranial magnetic stimulation (TMS) and magnetic resonance imaging (MRI) approaches were used to evaluate cortical excitability and brain structural morphometry in individuals with chronic stroke. Hemispheric differences and relationships between these measures and hand dexterity were evaluated. Results: Hemispheric differences were observed for TMS and MRI measures. Bilateral hand dexterity correlated with TMS resting motor threshold and precentral gyral thickness. Transcallosal inhibition across hemispheres was positively associated with midcallosal white matter volume. Regression modeling results demonstrated that combining TMS and MRI measures predicted unique amounts of variance in hand dexterity. Conclusions: Results confirm and extend findings showing differences in brain structure and function after stroke. Results suggested a structure-function relationship underlying interhemispheric connectivity in chronic stroke. The utility of combined TMS and MRI measures to predict motor function can be used in future investigations to aid identifying optimal biomarkers of stroke recovery to predict response to rehabilitation to maximize treatment outcomes.
Keywords: Stroke, transcranial magnetic stimulation, magnetic resonance imaging, cortical excitability, morphometry, rehabilitation, hand dexterity
