Enhanced motor function and its neurophysiological correlates after navigated low-frequency repetitive transcranial magnetic stimulation over the contralesional motor cortex in stroke
Affiliations: [a]
Department of Neurology, Berenson-Allen Center for Noninvasive Brain Stimulation, Beth Israel Deaconess Medical Center, Harvard Medical School, Brookline Avenue KS, Boston, MA, USA
| [b] Faculty of Medicine, Department of Physiology, King Saud University, Riyadh, Saudi Arabia
| [c]
Department of Neurology and The Burke Medical Research Institute, Weill Cornell Medical College, NY, USA
| [d] Institut Universitari de Neurorehabilitació Guttmann, Universidad Autónoma de Barcelona, Barcelona, Spain
Correspondence:
[*]
Corresponding author: Alvaro Pascual-Leone, M.D., Ph.D., Berenson-Allen Center for Noninvasive Brain Stimulation, Beth Israel Deaconess Medical Center, 330 Brookline Ave, Boston, MA 02215, USA. Tel.: +1 617 667 0203; Fax: +1 617 975 5322; E-mail: apleone@bidmc.harvard.edu.
Abstract: Background: The net effect of altered interhemispheric interactions between homologous motor cortical areas after unilateral stroke has been previously reported to contribute to residual hemiparesis. Using this framework, we hypothesized that navigated 1 Hz repetitive transcranial magnetic stimulation (rTMS) over the contralesional hemisphere would induce a stronger physiological and behavioural response in patients with residual motor deficit than in healthy subjects, because an imbalance in interhemispheric excitability may underlie motor dysfunction. Methods: Navigated rTMS was conducted in 8 chronic stroke patients (67.50±13.77 years) and in 8 comparable normal subjects (57.38±9.61 years). We evaluated motor function (Finger tapping, Nine Hole Peg test, Strength Index and Reaction Time) as well as the excitatory and inhibitory function (resting motor threshold, motor evoked potential amplitude, intra-cortical inhibition and facilitation, and silent period) of the stimulated and non-stimulated motor cortex before and after navigated rTMS. Results: rTMS induced an increase in excitability in the ipsilesional (non-stimulated) motor cortex and led to improved performance in the finger tapping task and pinch force task. These physiological and behavioral effects were more prominent (or robust) in the group of stroke patients than in the control group. Conclusion: Navigated low-frequency rTMS involving precise and consistent targeting of the contralesional hemisphere in stroke patients enhanced the cortical excitability of the ipsilesional hemisphere and the motor response of the hemiparetic hand.
