Effects of tDCS Combined With mCIMT or Mental Practice in Poststroke Patients

Eighty-four patients chronic post-stroke will be recruited to participate in the study. After screening to check the eligibility criteria and giving informed consent, the patients will be randomized into seven distinct groups (12 per group). All the patients will be submitted to 12 therapeutic sessions that will occur with a frequency of three times a week.

Before, immediately after and 1 month after the beginning of the experimental sessions patients will be submitted to an evaluation at each moment will be applied: (i) Fugl- Meyer Scale, (ii) Motor Activity Log Scale, (iii ) Jebsen-Taylor hand functional test, (iv) Independence Functional Measure (v) Box-Block Test, (vi) Dynamometry and (vii) Berg Balance Scale.

In experimental sessions, the subjects always receive physiotherapy treatment with conventional techniques, the protocol will follow the guidelines outlined in Clinical Practice Guideline for physical therapy in stroke patients with the Royal Dutch Society for Physical Therapy (2004). Besides physical therapy, the patient may be subjected to transcranial direct current stimulation (tDCS) associated with the techniques of modified constraint-induced movement therapy (mCIMT) or mental practice (MP).

tDCS protocol During tDCS sessions, the patients will be seated in a comfortable chair with head and arm rests. Continuous direct current will be applied by clinical microcurrent stimulator (Soterix, USA) using a pair of saline-soaked surface sponge electrodes (surface 35 cm2). For anodal and sham stimulation (the polarity refers always to the motor cortical electrode), the anode electrode will be placed over primary motor cortex (M1; EEG 10/20 system) of the affected hemisphere and cathode above contralateral orbit. For cathodal tDCS, the cathode will be positioned over M1 of the non-affected hemisphere and the anode was placed above the contralateral orbit. For bi-hemispheric tDCS the anode electrode will be placed over M1 of the affected hemisphere and the cathode over the M1 of the healthy hemisphere. Transcranial direct current stimulation will be administered with a current strength of 1 mA for 13 (anodal/bi-hemispheric tDCS) or 9 min (cathodal tDCS). Sham tDCS will be performed by current flow for 30 s, a method shown to achieve a good level of blinding mCIMT protocol The modified CIMT consisted of (i) complete immobilization of the non-paretic upper limb and (ii) intensive training the paretic upper limb and will be administered by a trained therapist, who was not involved in the pre-post evaluations.

Continuously for six hours daily over a period of four weeks, including weekend, all patients will be remained with complete immobilization of the non paretic upper limb. For this, an arm sling with the shoulder in adduction and internal rotation, elbow flexed at 90º, wrist and fingers in neutral position, made specifically for each patient will be used. They will be advised to use the restriction during their daily activities and instructed to remove it every hour for 10 minutes to perform stretching, which has been previously taught by the researchers to avoid functional deterioration caused by disuse. All muscle groups of the upper extremity will be stretched. A guide with instructions of the stretching will be distributed to patients. The patients will be instructed to take the immobilization on every day at same hour the tDCS sessions. In addition, the patients will be allowed to take the arm sling off during activities in which safety would be compromised, such as toileting, dressing, and bathing.

For intensive training the paretic upper limb, the patients will attend a gross motor and fine motor activities program performed for 1 hour per day, three times per week. Each task was performed for 2-3 minutes and the rest interval between tasks will be determined for each subject in order to avoid fatigue and excessive tiredness. The tasks will be progressively adapted by increasing speed or accuracy to allow improvement of patient performance. All tasks will be done with subjects sitting on a chair with standard dimensions and performed on support table. During training sessions, the patients will remain with the non-paretic arm immobilized.

Mental practice protocol Prior to experimental sessions, the mental capacity of subjects to learn the imagery techniques will be tested by the Kinesthetic and Visual Imagery Questionnaire and a chronometric test. The Kinesthetic and Visual Imagery Questionnaire is an imagery assessment tool comprised of 10 items, each scored on a five-point ordinal scale, including the image clarity (visual dimension) and the sensations intensity (kinesthetic dimension) of body movements. Each item describes an action: (i) neck flexion/extension, (ii) shoulder shrugging, (iii) forward trunk flexion, (iv) forward shoulder flexion, (v) elbow flexion, (vi) thumb to finger tips, (vii) knee extension, (viii) hip abduction, (ix) foot external rotation, and (x) foot tapping. Subjects physically execute each movement and immediately afterwards imagine performing the same movement. A score of 5 corresponds to the highest clarity/intensity, and a score of 1 corresponds to the lowest clarity/ intensity (for a review, see Malouin et al., 2007). The Kinesthetic and Visual Imagery Questionnaire scores allowed the researcher to assess each participant's abilities and decide whether the subject was a suitable candidate for MP. Comparing actual and imagined movement times, the chronometric test determined the motor imagery ability of participants.

The mental practice will consist of motor imagination of tasks. These tasks will consist of action for the patient to imagine themselves, with the greatest wealth of detail possible, performing motor activities with the hemiparetic upper limb, such as the movement of the touching thumb on each other's toes hand, or even the movement of bringing a cup towards his mouth. The technique of mental practice will be applied at the same time of the tDCS.