TDCS* and Laterality Trainnning in Patients With Chronic Neck Pain

Chronic neck pain leads to decreased quality of life and absenteeism at work, generating great personal and socio-economic impact. It has been shown that patients with chronic pain have late recognition of the laterality of the hand, which is related to the duration of symptoms and pain evoked by the execution of the movement. These findings suggest that chronic pain and the consequent disuse of certain motor functions may involve a reorganization of the cortical representation of the body scheme or motor planning.

Non-invasive neuromodulation, such as transcranial direct current stimulation (TDCS), allows modulating cortical excitability and promoting pain relief.

This study intends to verify the effects of the association of noninvasive brain stimulation with TDCS with an intervention with visual and motor stimuli related to laterality in patients with neck pain.

The study will be controlled, randomized, double-blind and will include patients with chronic neck pain, divided into four groups:

1. active TDCS associated with laterality recognition stimuli (n = 25);
2. active TDCS associated with landscape recognition stimuli (n = 25);
3. TDCS sham associated with laterality recognition stimuli (n = 25);
4. TDCS sham associated with landscape recognition stimuli (n = 25);

Eight induction sessions will be held twice a week for four weeks. Patients who present a positive response in the first reassessment (responders) will remain in the study follow-up and will undergo a weekly maintenance session, for four weeks, and two more biweekly sessions.

The following instruments will be used for evaluation: motor safety thresholds through a MagVenture pulse generator with a flat surface coil, figure 8; OPAL, device with sensors; Recognize™ application; Visual Analog Scale (VAS); Brief Pain Inventory (BDI); Clinical Global Impression - ICG (patient and evaluated version); Pain McGill Standard Questionnaire - Short Format; Hospital Anxiety and Depression Scale (HAD); 36-item summary health survey from the Medical Outcomes Study (SF-36); Mini best test; neurodynamic tests (upper limb tension tests); and quantitative sensory tests. In addition to the pre- and post-intervention assessments, there will be post-treatment follow-up performed three, six and 12 months after randomization by telephone or e-mail. It is expected that the combined application of tDCS with stimuli related to laterality will have positive effects in patients with neck pain, impacting on variables such as pain, functional movements and quality of life of these patients.

Eligibility Criteria:
Inclusion Criteria:

* participants over 18 years old;
* pain in the cervical region, lasting more than three months and with intensity greater than 40/100 on the visual analog scale

Exclusion Criteria:

* history of seizures or epilepsy,
* history of head trauma,
* intracranial hypertension,
* intracranial metal clip,
* pregnant or breastfeeding women,
* skin lesions at the current application site;
* changes in sensitivity and allergy in the electrode positioning region.
* intermittent pain;
* Cancer;
* cardiac pacemaker;
* severe spinal diseases, such as recent fractures or ankylosing spondylitis;
* serious cardiorespiratory diseases;
* participants who refuse to sign the Free and Informed Consent Form.