Chronic pain is an important public health issue. Moreover, its adequate management is still considered a major clinical problem, mainly due to its incredible complexity and still poorly understood pathophysiology. Recent scientific evidence coming from neuroimaging research, particularly functional magnetic resonance (fMRI) and positron emission tomography (PET) studies, indicates that chronic pain is associated with structural and functional changes in several brain structures that integrate antinociceptive pathways and endogenous modulatory systems. Furthermore, the last two decades have witnessed a huge increase in the number of studies evaluating the clinical effects of noninvasive neuromodulatory methods, especially transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS), which have been proved to effectively modulate the cortical excitability, resulting in satisfactory analgesic effects with minimal adverse events. Nevertheless, the precise neuromechanisms whereby such methods provide pain control are still largely unexplored. Recent studies have brought valuable information regarding the recruitment of different modulatory systems and related neurotransmitters, including glutamate, dopamine, and endogenous opioids. However, the specific neurocircuits involved in the analgesia produced by those therapies have not been fully elucidated. This review focuses on the current literature correlating the clinical effects of noninvasive methods of brain stimulation to the changes in the activity of endogenous modulatory systems.
ResumoO bruxismo é descrito como um movimento orofacial, denominado parafunção, cuja etiologia é complexa e multifatorial. O presente estudo teve como objetivo, facilitar o entendimento das possíveis causas dessa desordem e sua relação com o Sistema Nervoso Central, através de uma revisão de literatura. Alguns autores (4,23,19) afirmam a hipótese de o bruxismo ser mediado centralmente, tornando o estresse emocional e a ansiedade, fatores importantes para seu desencadeamento. Como auxílio diagnósti-co, a polissonografia (PSG) é uma importante ferramenta, porém devido ao custo ainda oneroso, poucos estudos foram encontrados correlacionando a PSG e o bruxismo, sendo de grande importância que mais pesquisas sejam realizadas sobre o assunto.Palavras-chave: bruxismo do sono; dopamina e bruxismo; polissonografia e bruxismo. AbstRAct Bruxism and its relationship with the central nervous system: Literature ReviewIntrodução A atividade parafuncional é um dos fatores principais associados à DTM. As atividades da musculatura mastigatória podem ser divididas em dois tipos básicos: funcional que inclui mastigar, falar e deglutir e parafuncional (não funcional), que inclui apertar ou ranger os dentes (bruxismo) e vários outros hábitos orais. Os danos causados aos portadores de hábitos parafuncionais motivam estudos que buscam desenvolver terapias mais eficazes para controle e tratamento das mesmas, sendo o bruxismo a parafunção mais pesquisada (7).O bruxismo é descrito como um distúrbio de movimentos estereotipados, geralmente associado com microdespertares. Existe também o bruxismo da vigília. Os sons produzidos pela fricção dos dentes normalmente são percebidos pelo companheiro. Entre os efeitos indesejáveis resultantes desse distúrbio estão: desgaste dos dentes, hipersensibilidade dentária a estímulos térmicos, dor orofacial e cefaleia temporal (2, 6).A relação de substâncias neuroquímicas, chamadas catecolaminas, com o bruxismo, está em destaque atualmente, porém, ainda há poucos estudos descrevendo os detalhes desse assunto. A dopamina é uma dessas substân-cias e corresponde a mais da metade do conteúdo de catecolaminas do SNC (23). Acredita-se que ela pode estar diretamente relacionada com a inibição de movimentos espontâneos e ter ligação com manifestações de estresse e ansiedade. Com isso, alterações de seus níveis podem ser responsáveis pelo desencadeamento de movimentos repetitivos coordenados, sugerindo o envolvimento do sistema dopaminérgico e da neurotransmissão central na etiologia do bruxismo (22,21,19,3,24, 25). Revisão de LiteraturaSegundo OKESON (15), estudos epidemiológicos revelam que a maior parte dos sintomas de DTM é relatada pela faixa etária de 20 a 40 anos e sua etiologia é complexa e multifatorial. Acredita-se que 85% a 90% da população rangem os dentes em algum grau durante a vida e somente cerca de 5% desses pacientes, apresenta o bruxismo como condição clínica. CUNALI et al. (6) afirmaram que, até o momento, as melhores ferramentas para o diagnóstico de bruxismo e DTM em pesquisa são, respectiva...
Background Temporomandibular Disorder (TMD) is a generic term applied to describe musculoskeletal disorders that affect the temporomandibular joint (TMJ), the masticatory muscles and the related structures. TMD comprises two groups of disorders, namely intra-articular TMD and masticatory muscle disorders. There is still difficulty in establishing the effectiveness of different therapeutic modalities for TMD with robust evidence, despite the large volume of publications in the area. The lack of outcomes standardization may represent a limiting factor in the search for scientific evidence. Objective This study aims to develop a core outcome sets (COS) for clinical trials in intra-articular TMD and masticatory muscle disorders. Methods The protocol for determining the COS-TMD will consist of three phases: 1. Synthesis of TMD Management Intervention Outcomes. The identification of outcomes will be carried out through a systematic review, which will include randomized clinical trials that evaluated the effectiveness of interventions used in TMD management. 2. Through a two-round international Delphi survey, the list of outcomes will be scored by three panels of stakeholders. 3. A representative sample of key stakeholders will be invited to participate in a face-to-face meeting where they can discuss the results of the Delphi survey and determine the final core set. Conclusions The implementation of this protocol will determine the COS-TMD, which will be made available for use in all TMD clinical studies. The use of COS when planning and reporting TMD clinical trials will reduce the risk of publication bias and enable proper comparison of results found by different studies.
Background. The uncoordinated activity of the superior and inferior parts of the lateral pterygoid muscle (LPM) has been suggested to be one of the causes of temporomandibular joint (TMJ) disc displacement. A therapy for this muscle disorder is the injection of botulinum toxin (BTX), of the LPM. However, there is a potential risk of side effects with the injection guide methods currently available. In addition, they do not permit appropriate differentiation between the two bellies of the muscle. Herein, a novel method is presented to provide intraoral access to the superior head of the human LPM with maximal control and minimal hazards. Methods. Computational tomography along with digital imaging software programs and rapid prototyping techniques were used to create a rapid prototyped guide to orient BTX injections in the superior LPM. Results. The method proved to be feasible and reliable. Furthermore, when tested in one volunteer it allowed precise access to the upper head of LPM, without producing side effects. Conclusions. The prototyped guide presented in this paper is a novel tool that provides intraoral access to the superior head of the LPM. Further studies will be necessary to test the efficacy and validate this method in a larger cohort of subjects.
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