Effects of Bihemispheric Transcranial Direct Current Stimulation on Motor Function in Stroke Patients

The Effect of Bihemispheric Transcranial Direct Current Stimulation Therapy on Upper Extremity Motor Functions in Stroke Patients

Motor impairment (impairment of movement) due to stroke is one of the leading disabilities in adults. In addition to established means of facilitating motor recovery after stroke such as physical and occupational therapy, a variety of experimental rehabilitation approaches have been tested. Although there have been significant advances in stroke rehabilitation with these techniques and treatments, research on this subject is continuing. Recent studies have focused on non-invasive brain stimulation techniques. Transcranial magnetic stimulation (TMS) or transcranial direct current stimulation (tDCS) therapies, which are methods of non-invasive brain stimulation that may be effective on cerebral remodelling, aim to reestablish the disturbed balance between the anatomic areas of the brain seen in stroke patients.

The primary aim of this study is to evaluate the effectiveness of bihemispheric transcranial direct current stimulation (tDCS) applications on the upper extremity motor functions of patients with stroke.

Motor impairment due to ischemic and hemorrhagic stroke is one of the leading disabilities in adults. In addition to established means of facilitating motor recovery after stroke such as physical and occupational therapy, a variety of experimental rehabilitation approaches have been tested. Recent developments include noninvasive brain stimulation techniques such as repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS). The use of these tools is based on neurophysiologic studies demonstrating an imbalance of interhemispheric interactions which appears to interfere with the recovery process.

The model of interhemispheric imbalance provides a framework for developing hypotheses based on its 2 facets: 1) upregulating excitability of intact portions of the ipsilesional motor cortex and 2) downregulating excitability of the contralesional motor cortex to modulate its unrestrained inhibitory influence on ipsilesional regions. Studies to date have shown have shown the beneficial effects of tDCS on motor skills and motor learning.

Bihemispheric tDCS may potentiate the effects of anodal stimulation to the lesional hemisphere through additional modulation of interhemispheric interactions via cathodal stimulation to the contralesional motor cortex.

The primary aim of this prospective, randomized, sham controlled study is to evaluate the effectiveness of bihemispheric transcranial direct current stimulation (tDCS) applications on the upper extremity motor functions of patients with stroke.

Inclusion Criteria:

1. 18-75 years old, female or male
2. Clinical evaluation consistent with hemiplegia
3. First time stroke with brain computerized tomography (CT) and / or magnetic resonance imaging (MRI) findings consistent with stroke
4. At least 3 months since stroke onset
5. Presence of a stable medical condition
6. Preserved cognitive function as determined by a mini mental state examination score of 23 and above

Exclusion Criteria:

1. Presence of a sensory aphasia
2. Presence of neglect syndrome
3. A history of epilepsy
4. Presence of a pacemaker
5. Previous history of stroke
6. History of previous cranial surgery
7. Presence of a brain tumour
8. Presence of an intracranial metallic implant
9. Marked hearing / visual impairment
10. Presence of severe spasticity (grade 3-4 according to the modified Ashworth scale)