Motor cortex plasticity predicts recovery in acute stroke

Area of Science:

• Neuroscience
• Neurology
• Rehabilitation Medicine

Background:

• Repetitive transcranial magnetic stimulation, specifically intermittent theta burst stimulation (iTBS), can induce neuroplastic changes such as long-term potentiation (LTP)-like and long-term depression (LTD)-like effects.
• Understanding the correlation between these iTBS-induced neuroplastic changes and functional recovery in acute stroke patients is crucial for optimizing treatment strategies.

Purpose of the Study:

• To investigate whether LTP- and LTD-like changes induced by iTBS in patients with acute ischemic stroke correlate with their functional outcome at 6 months post-stroke.
• To assess the relationship between baseline hemispheric excitability and stroke prognosis.

Main Methods:

• Evaluated 17 acute ischemic stroke patients.
• Measured motor threshold and motor-evoked potential (MEP) amplitude of the affected hemisphere (AH) and unaffected hemisphere (UH) under baseline conditions.
• Administered iTBS to the AH and reassessed MEP amplitude.
• Correlated baseline and post-iTBS excitability measures with functional recovery at 6 months.

Main Results:

• Baseline MEP amplitude was smaller and motor threshold higher in the AH compared to the UH.
• Higher baseline MEP values in the UH correlated with poorer prognosis.
• iTBS significantly increased AH MEP amplitude, which correlated with improved recovery.
• A trend towards decreased UH MEP amplitude was observed, and this decrease, combined with AH changes, further improved the correlation with recovery.

Conclusions:

• Functional recovery after acute ischemic stroke is positively correlated with LTP-like changes in the affected hemisphere induced by iTBS.
• LTD-like changes in the unaffected hemisphere also contribute to better functional recovery.
• Baseline excitability of the unaffected hemisphere is inversely correlated with stroke prognosis.