Background Transcranial Direct Current Stimulation (tDCS) and Transcranial Magnetic Stimulation (TMS) have been described as promising alternatives to treat different pain syndromes. This study evaluated the effects of TMS and tDCS in the treatment of chronic orofacial pain, through a systematic review. Methods An electronic search was performed in major databases: MEDLINE, Scopus, Web of Science, Cochrane, Embase, LILACS, BBO, Open Gray and CINAHL. The eligibility criteria comprised randomized clinical trials (RCTs) that applied TMS or tDCS to treat chronic orofacial pain. The variables analyzed were pain, functional limitation, quality of life, tolerance to treatment, somatosensory changes, and adverse effects. The risk of bias was assessed through the Cochrane Collaboration tool, and the certainty of evidence was evaluated through GRADE. The protocol was registered in the PROSPERO database (CRD42018090774). Results The electronic search resulted in 636 studies. Thereafter, the eligibility criteria were applied and the duplicates removed, resulting in eight RCTs (four TMS and four tDCS). The findings of these studies suggest that rTMS applied to the Motor cortex (M1), the dorsolateral prefrontal cortex (DLPFC) and the secondary somatosensory cortex (S2) provide adequate orofacial pain relief. Two studies reported significant pain improvement with tDCS applied over M1 while the other two failed to demonstrate significant effects compared to placebo. Conclusions rTMS, applied to M1, DLPFC or S2, is a promising approach for the treatment of chronic orofacial pain. Moreover, tDCS targeting M1 seems to be also effective in chronic orofacial pain treatment. The included studies used a wide variety of therapeutic protocols. In addition, most of them used small sample sizes, with a high risk of biases in their methodologies, thus producing a low quality of evidence. The results indicate that further research should be carried out with caution and with better-standardized therapeutic protocols.

Background: Hypokinetic dysarthria -with hypophonia as its main symptom-is a common feature of Parkinson's disease, affecting approximately 90% of patients. Hypophonia, characterized by reduced speech volume, leads to difficulties in communication with others due to decreased speech intelligibility. Current treatments involve intensive and cognitively demanding behavioral therapies such as the Lee Silverman Voice Treatment (LSVT). The SpeechVive is a wearable device that produces noise to elicit increased vocal intensity utilizing a natural reflex through the Lombard effect. Methods: We propose a multicenter, phase III, two-armed, parallel, open-label, randomized controlled trial comparing the effectiveness of LSVT with SpeechVive. We seek to assign 238 patients to either LSVT or SpeechVive device in a 1:1 ratio through a stratified permuted block randomization. Patients ages 50 to 80 years, diagnosed with idiopathic Parkinson's Disease based on MDS-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) criteria, a Hoehn and Yahr stage 2 and 3, on stable dopaminergic doses for the past 3 months, with perceived communication difficulties will be included in the trial. Patients will be excluded if they present additional neurodegenerative diseases, prior stroke, laryngeal pathologies, hearing or a severe visual impairment, or who underwent speech therapy or have a deep brain stimulation electrode implanted. The primary outcome is speech intelligibility measured through the Speech Intelligibility Test (SIT) for windows. Secondary outcomes include adherence, the vocal intensity measured with Sound Pressure Level (SPL), Vocal Handicap Index (VIH), and Parkinson's Disease Questionary-39. We will measure each outcome at baseline and after eight weeks of treatment. Our principal statistical analysis is multiple linear regression analysis, with age, gender, site, and PD severity as covariates. Discussion: We present a protocol for a randomized controlled trial addressing an important issue that hampers the ability of Parkinson's Disease patients to communicate effectively. We aim at exploring SpeechVive as an alternative, more accessible treatment for hypophonia in patients with Parkinson's Disease.