Corticomuscular coherence in the acute and subacute phase after stroke

- Corticomuscular coherence (CMC) and intermuscular coherence (IMC) were reduced in acute and subacute stroke compared to healthy controls.
- CMC was localized above the contralateral sensorimotor cortex in both patients and controls.
- Improvement of hand motor performance did not require changes in CMC or IMC.

ObjectiveStroke is one of the leading causes of physical disability due to damage of the motor cortex or the corticospinal tract. In the present study we set out to investigate the role of adaptations in the corticospinal pathway for motor recovery during the subacute phase after stroke.MethodsWe examined 19 patients with clinically diagnosed stroke and 18 controls. The patients had unilateral mild to moderate weakness of the hand. Each patient attended two sessions at approximately 3 days (acute) and 38 days post stroke (subacute). Task-related changes in the communication between motor cortex and muscles were evaluated from coupling in the frequency domain between EEG and EMG during movement of the paretic hand.ResultsCorticomuscular coherence (CMC) and intermuscular coherence (IMC) were reduced in patients as compared to controls. Paretic hand motor performance improved within 4-6 weeks after stroke, but no change was observed in CMC or IMC.ConclusionsCMC and IMC were reduced in patients in the early phase after stroke. However, changes in coherence do not appear to be an efficient marker for early recovery of hand function following stroke.SignificanceThis is the first study to demonstrate sustained reduced coherence in acute and subacute stroke.