Evaluation of differences in brain neurophysiology and morphometry associated with hand function in individuals with chronic stroke.
OBJECTIVE
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.
Division of Physical Therapy, Department of Rehabilitation Medicine, School of Medicine, Emory University, Atlanta, GA, USA.
Michael R
MR
Borich
Department of Physical Therapy, Faculty of Medicine, University of British Columbia Vancouver, BC, Canada.
Jason L
JL
Neva
Department of Physical Therapy, Faculty of Medicine, University of British Columbia Vancouver, BC, Canada.
Lara A
LA
Boyd
D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000473:pathology* / Q000503:physiopathology*; D002908:Chronic Disease; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006225:Hand / Q000294:innervation* / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009473:Neuronal Plasticity / Q000502:physiology; D012720:Severity of Illness Index; D013223:Statistics as Topic; D020521:Stroke / Q000473:pathology*; D050781:Transcranial Magnetic Stimulation
Stroke; cortical excitability; hand dexterity; magnetic resonance imaging; morphometry; rehabilitation; transcranial magnetic stimulation