Accuracy in virtual task for upper limbs associated with transcranial direct current electrical stimulation in people with parkinson's disease

Abstract

Parkinson's disease is a progressive neurological disorder characterized by a decrease in the production of dopamine by the substantia nigra, which presents several motor comorbidities1,2. Therefore, these patients are part of constant rehabilitation programs, and professionals in the field seek effective and modern solutions for these patients' functional recovery. Recent studies encourage the use of the combination of therapies and technologies, and in this context, Virtual Reality and Transcranial Direct Current Stimulation (tDCS) has been used in several studies3, however, not yet in a combined way. Virtual reality is a platform where the patient interacts with the game, where electronic devices are used, enabling patients to interact in an experience very close to reality4. In rehabilitation, virtual reality can improve motor learning, offering continuous feedback that allows the repetitive practice, thus stimulating the individual in motor and cognitive aspects5. tDCS is a non-invasive neuromodulation technique that produces benefits in sensorimotor and cognitive functions6-8. People with PD have difficulties in consolidating new motor tasks, and tDCS can be a tool that has fewer adverse side effects when compared to drug therapies9. OBJECTIVES: The main objective is to observe the short-term effect of combined tDCS therapy (comparing Active and Sham) and VR on the accuracy of patients with Parkinson's disease. MATERIALS AND METHODS: This project was approved by the CAAE ethics committee: 02908218.0.0000.5390, registered in Clinical Trials: NCT04527809. It is a parallel, controlled, double-blind, randomized clinical trial. The intervention was performed in one day only. Two researchers applied tDCs + VR, while blinding was previously carried out by a third person, who provided a code, which was inserted in the tDCs device, for each patient. The total duration of the tDCs stimulus was 18 minutes, with the patients playing MoveHero for 4 minutes with the upper limbs and 4 minutes with the lower limbs, 5 minutes for adaptation to the current before the start of the game, and 5 minutes after the game. It was included 55 patients diagnosed with Parkinson's disease, with the Hoehn &Yarh scale between 1 – 3 and without age limit who agreed to participate in the study were included. Patients who used wheelchairs and auxiliary walking devices used Deep Brain Stimulation (DBS) and were unable to complete the procedures were excluded. The patients were divided into two groups, Group A: Active (26 patients), Group S: Sham (29 patients). In group A, active tDCS was induced, with the anodal electrode positioned in the area of the primary motor cortex (area M1) and the cathodal electrode positioned in the contralateral supra-orbital region. In group A, active tDCS was induced, with a current of 2mA with an ascent ramp of 20 seconds and descent of 20 seconds too, which were associated with a Virtual Reality task, the MoveHero game. In group S, patients performed the same task, but the current was interrupted after the stimulation upward ramp. Before beginning the intervention, the patients were evaluated using an Anamnesis, the MiniBESTest, Berg Scale, Mini Mental Test, Unified Parkinson's Disease Assessment Scale (UPDRS), and to observe the disease staging, it was used the Hoehn&Yahr scale. The MoveHero game was performed in front of a computer, the image was captured by the Webcam, the individual must reach spheres, which fall from the top of the screen, when they hit a target, performing an interception task. The game performance was assessed, observing the accuracy of the participants when they reached the spheres in the pre-determined targets. RESULTS: There was no difference between groups A and S. The paired t-test, done to compare performance between groups, showed that groups A and S had similar performance, with no significant difference both on the right side (A: 487±352; S: 438±248; p= 0,552) and on the left side (A: 451±305; S: 416±260; p= 0,650). There were no differences between the average performance block at the beginning and end of the practice, that is, in group A, there was no difference from the beginning to the end of the practice neither on the right side (D1 348±292 to D2 333±168; p= 0,449) nor the left side, (E1 367±244 to E2 339±190; p= 0,675), as well as there was none in group S (D1 358±251 to D2 417±256; p= 0,250; E1 415±269 to E2 352±317; p= 0,348). DISCUSSION: It was observed that tDCs probably did not influence the interception task, perhaps because the individuals did not have time to adapt to the proposed task, since the application of the protocol was only one day, without the patients having the previous contact with the game presented. The present study has some limitations, which are: (1) short intervention time, perhaps with a longer session protocol, patients would have improved; (2) without previous contact with the game, contact with the game was immediate, without having practiced before the intervention. We suggest that future studies apply combined therapies of tDCS+ VR in patients with Parkinson's disease in longitudinal studies. CONCLUSION: The present study demonstrates that patients with Parkinson's Disease, who underwent combined therapy for tDCS and RV for upper limbs did not present differences between activetDCS and sham, for movement accuracy. Just as there was no performance improvement during practice, which may be due to the short intervention time (one day).