Motor cortex excitability in stroke before and after constraint-induced movement therapy

Area of Science:

• Neuroscience
• Rehabilitation Medicine
• Motor Control

Background:

• Stroke often leads to motor cortex dysfunction and altered excitability.
• Chronic stroke patients may exhibit motor cortex disinhibition.
• Understanding these changes is crucial for effective rehabilitation.

Purpose of the Study:

• To investigate motor cortex excitability in chronic stroke patients.
• To explore how intense physiotherapy, specifically constraint-induced movement therapy (CIMT), affects motor cortex excitability.
• To correlate changes in excitability with motor function recovery.

Main Methods:

• 12 chronic stroke patients underwent 12 days of CIMT.
• Transcranial magnetic stimulation (TMS) assessed intracortical inhibition (ICI), motor evoked potentials (MEPs), and motor thresholds (MTs).
• Motor function was evaluated using standardized clinical scales.

Main Results:

• Motor cortex disinhibition was observed in the affected hemisphere pre-therapy, correlating with spasticity.
• MEP amplitudes and MTs reflected corticospinal pathway function.
• Post-therapy, significant changes in ICI were noted in the affected hemisphere, with both decreases and increases observed, alongside motor function improvements.

Conclusions:

• Chronic stroke patients exhibit motor cortex disinhibition.
• CIMT induces changes in motor cortex excitability, primarily in the lesioned hemisphere, through modulation of ICI.
• CIMT effectively improves motor function in the chronic stage post-stroke.