Article

Contralesional hemispheric repetitive transcranial magnetic
stimulation (rTMS) may improve motor function in mild to moderate stroke and
effects are considered to be mediated through transcallosal motor fibers.
OBJECTIVE: This study aimed to investigate the safety of contralesional rTMS in a
selected group of severe chronic stroke patients. METHODS:
Ten sessions of 1 Hz
rTMS were applied to contralesional primary motor cortex (M1) using
neuronavigated stimulation and changes in motor impairment were evaluated before,
during and after rTMS applications and at 4-weeks follow-up. Neurophysiological
response to stimulation was assessed through cortical excitability evaluations.
The relationship between functional and neurophysiological response to rTMS and
microstructural integrity of transcallosal motor fibers were searched using
diffusion tensor imaging (DTI) based fractional anisotropy (FA). RESULTS: rTMS
was well-tolerated with high compliance and no dropouts; no seizures or motor
worsening occurred. Transcallosal FA values revealed a positive linear
relationship with the mild motor improvement detected after rTMS while higher FA
values were observed in subjects with better motor outcome. Cortical excitability
showed a significant change in contralesional short-interval intracortical
inhibition indicating altered plasticity following rTMS. CONCLUSIONS: Our results
suggest that noninvasive neuromodulation of the contralesional hemisphere may
present a possibility to assist adaptive neuroplastic changes in severe chronic
stroke. Implementation of DTI-derived measures of transcallosal microstructural
integrity may allow for individually-tailored interventions to guide processes of
interhemispheric neuroplasticity. Further research is warranted to establish the
clinical value of these findings in neurorehabilitation settings for subjects
with chronic severe stroke.

Langue : ANGLAIS