Individualizing Transcranial Direct Current Stimulation to improve motor learning in stroke

Improving learning abilities after stroke

After a stroke, patients often end up with motor problems such as a central paresis. A central paresis may have negative symptoms, such as patients losing the ability to move fingers, elbow and wrist independently. When they bow their elbow, they end up with a twisted wrist and their fingers crammed into the palm of their hand. Positive symptoms may occur too, for example increased muscle tone. Due to these symptoms the patient may lose the ability to voluntary control his motor behaviour.

Conclusive answer
In this project, the use of Transcranial Direct Current Stimulation to improve the arm-hand movement in CVA patients will be studied. tDCS is a technique which applies a small current to parts of the brain resulting in a more efficient learning process. Previous studies on application of this technique on CVA patients have shown varying results and many questions await an answer. What is the optimal electrode placement in a specific individual, for example? And how do we take into account the type and location of he stroke? This project should answer the question why this technology works better in some cases than in others.

Precise stimulation
For each patient involved in the study, first an EEG is made to determine which part of the brain in this specific patient is controlling the hand-arm movement. In addition to that, an MRI is made to image lesions arising from the stroke, which could inhibit the electrical current from reaching the desired brain area. Based on these measurements, the researchers will develop a model to predict the optimal placement of the electrodes to stimulate the exact area responsible for motor control. That part of the brain is electrically stimulated prior to each training session by a physical therapist. After this, the result of the training is evaluated.

Technological challenge
To image the result of the electrical stimulation in the brain, 4DEEG measurements will be used. One of the technological challenges the researchers face is the fact that the electrical stimulus applied in the tDCS method is much larger than the electrical signals arising from the resulting brain activity. Therefore, within the project a special EEG cap will be developed which can be used both for stimulation and for measurement.

Application perspective
Gerard Ribbers, professor Neurorehabilitation at the Erasmus University MC and Neurorehabilitation physician at Rijndam Rehabilitation Institute
‘I hope this research project will lead to more insight into the mechanisms behind motoric rehabilitation, resulting in tailor-made treatment plans. The current rehabilitation therapy is primarily trial and error based. We want to be able to predict which patient will benefit from what kind of training. This will result a in a faster and better recovery and efficient use of therapeutic facilities. Furthermore,  I hope we will be able to actually image the dynamics of the rehabilitation process. We know that patients can improve importantly in the first two months after a CVA, but we don’t know what mechanisms in the brain are the driving forces behind this.’

Partners
Delft University of Technology, Erasmus University Rotterdam, Radboud University Nijmegen, Rijndam Rehabilitation Center, Twente Medical Systems International, Twente University, VU University Amsterdam