Transcranial direct current stimulation in stroke - Motor excitability and motor function.
Sinan Yasaroglu1, Joachim Liepert1
1Kliniken Schmieder, Allensbach, Germany.
Summary
Anodal transcranial direct current stimulation (tDCS) reduced motor cortex inhibition in stroke patients, but did not improve motor performance. Cathodal tDCS had no effect on excitability or performance.
Area of Science:
- Neuroscience
- Rehabilitation Medicine
- Neuromodulation
Background:
- Stroke often impairs motor function and alters motor cortex excitability.
- Transcranial direct current stimulation (tDCS) is being investigated as a therapeutic tool for stroke recovery.
- Understanding tDCS effects on motor excitability is crucial for optimizing stroke rehabilitation.
Purpose of the Study:
- To investigate the effects of a single session of anodal and cathodal tDCS on motor performance and motor cortex excitability in subacute stroke patients.
- To determine if tDCS modulates specific intracortical inhibitory and facilitatory circuits.
- To explore the relationship between baseline motor excitability and response to tDCS.
Main Methods:
- Twenty subacute stroke patients underwent single sessions of anodal and cathodal tDCS over the affected hemisphere.
- Motor performance was assessed using the Box and Block Test (BBT).
- Motor cortex excitability was measured using paired pulse transcranial magnetic stimulation (TMS) to assess short interval intracortical inhibition (SICI), intracortical facilitation (ICF), and long interval intracortical inhibition (LICI) before and after tDCS.
Main Results:
- Anodal tDCS significantly decreased SICI, indicating disinhibition, but did not affect ICF or LICI.
- Cathodal tDCS did not alter any measures of motor excitability.
- Neither anodal nor cathodal tDCS resulted in significant changes in motor performance (BBT scores).
- Baseline SICI in the affected hemisphere was lower than in the unaffected hemisphere and correlated with post-anodal tDCS BBT changes.
Conclusions:
- Anodal tDCS selectively modulates intracortical inhibitory circuits in stroke patients, leading to disinhibition.
- The observed disinhibition did not translate to immediate improvements in motor performance.
- These findings enhance understanding of tDCS-induced neuromodulation in the stroke population.
