Asymmetric activation of temporalis, masseter, and sternocleidomastoid muscles in temporomandibular disorder patients

The aim of this study was to analyze the symmetry of the electromyographic (EMG) activity of the temporalis, masseter, and sternocleidomastoid (SCM) muscles in volunteers divided into a control group and a temporomandibular disorder (TIMID) group. The surface EMG recordings were made during mandibular rest position, maximal intercuspal position, and during the chewing cycle. Normalized EMG waves of paired muscles were compared by computing a percentage overlapping coefficient (POC). The difference between the groups and between the static and dynamic clenching tests was analyzed through repeated measures, ANOVA. Symmetry of the temporalis, masseter, and SCM muscles activity was smaller in the TMD group compared to the control group. The mandibular postures were also significantly different among themselves. The asymmetric activation of jaw and neck muscles was interpreted as a compensatory strategy to achieve stability for the mandibular and cervical systems during masticatory function.261596

Atividade elétrica dos músculos cervicais e amplitude de movimento da coluna cervical em indivíduos com e sem DTM Electrical activity of cervical muscles and range of movement of cervical column in individuals with and without DTM

O objetivo da pesquisa foi avaliar a atividade elétrica e a dor à palpação dos músculos cervicais, a amplitude de movimento (ADM) da coluna cervical e a relação entre atividade elétrica e ADM cervical em indivíduos com e sem desordem temporomandibular (DTM). Participaram do estudo 53 voluntários, sendo 24 com DTM e 29 sem, de ambos os gêneros, com 18 a 32 anos de idade. A DTM foi diagnosticada pelo critério de diagnóstico em pesquisa para DTM (Research Diagnostic Criteria for Temporomandibular Disorders). A eletromiografia dos músculos esternocleidomastoídeo (ECOM) e trapézio superior foi realizada bilateralmente, na situação de repouso, com frequência de 2 KHz e filtro passa-faixa de 10-1000 Hz. As medidas de ADM de flexão, extensão, lateroflexão e rotação foram realizadas com um flexímetro e a comparação entre os grupos contou com o teste de Mann Whitney. O teste de Spearman foi aplicado para a correlação entre as variáveis, com nível de significância de 5%. Não foi verificada nenhuma diferença na ADM cervical entre os grupos. A atividade elétrica demonstrou-se significativamente maior nos músculos ECOM direito (p=0,0130), trapézio superior direito (p=0,0334) e esquerdo (p=0,0335) no grupo DTM em relação ao grupo controle. Não houve correlação significante entre atividade elétrica e ADM cervical. A dor nos músculos cervicais apresentou-se significativamente maior apenas no músculo ECOM direito (p=0,0055). Conclui-se que os grupos estudados registraram diferença na atividade elétrica dos músculos cervicais, sendo esta maior em indivíduos com DTM.<br>The aim of the research was to evaluate the electrical activity and pain on palpation of the cervical muscles, the cervical range of motion (ROM) and the relationship between electrical activity and ROM in individuals with and without temporomandibular disorder (TMD). Fifty three volunteers took part in the study, being 24 with TMD and 29 without, both genders, from 18 to 32 years old. The TMD was diagnosed through Research Diagnostic Criteria for Temporomandibular Disorder (RDC/TMD). The electromyografhy of Sternocleidomastoideus (SCM) and upper trapezius muscles was carried out bilaterally during rest situation, with a frequency of 2 KHz and band-pass filter of 10-1000Hz. The measures of flexion, extension, lateral tilt and rotation ROM were acquired through a fleximeter and the comparison between groups was analyzed by Mann-Whitney test. The Spearman test verified the correlation between the variables, with 5% of significance level. There were no differences in the cervical ROM between the groups. The electrical activity was significantly higher in the right SCM (p=0,0130), left (p=0,0335) and right (p=0,0334) trapezius muscles in the TMD group. There were no significant correlations between electrical activity and cervical ROM. Pain in the neck muscles was significantly higher only in the right SCM (p=0,0055). It is concluded that the studied groups had difference in the electrical activity of the cervical muscles, which was larger in the individuals with TMD