Abstract
Background.
Recovery of upper limb function post-stroke can be partly predicted by
initial motor function, but the mechanisms underpinning these
improvements have yet to be determined. Here, we sought to identify
neural correlates of post-stroke recovery using longitudinal
magnetoencephalography (MEG) assessments in subacute stroke survivors.
Methods.
First-ever, subcortical ischemic stroke survivors with unilateral mild
to moderate hand paresis were evaluated at 3, 5, and 12 weeks after
stroke using a finger-lifting task in the MEG. Cortical activity
patterns in the β-band (16-30 Hz) were compared with matched healthy
controls.
Results.
All stroke survivors (n=22; 17 males) had
improvements in action research arm test (ARAT) and Fugl-Meyer upper
extremity (FM-UE) scores between 3 and 12 weeks. At 3 weeks post-stroke
the peak amplitudes of the movement-related ipsilesional β-band
event-related desynchronization (β-ERD) and synchronization (β-ERS) in
primary motor cortex (M1) were significantly lower than the healthy
controls (p<0.001) and were correlated with both the FM-UE and ARAT
scores (r=0.51-0.69, p<0.017). The decreased β-ERS peak amplitudes
were observed both in paretic and non-paretic hand movement particularly
at 3 weeks post-stroke, suggesting a generalized disinhibition status. The peak amplitudes of ipsilesional
β-ERS at week 3 post-stroke correlated with the FM-UE score at 12 weeks
(r=0.54, p=0.03) but no longer significant when controlling for the
FM-UE score at 3 weeks post-stroke.
Conclusions.
Although early
β-band activity does not independently predict outcome at 3 months after
stroke, it mirrors functional changes, giving a potential insight into
the mechanisms underpinning recovery of motor function in subacute
stroke.
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