Effect of conventional TENS on pain and electromyographic activity of masticatory muscles in TMD patients

Abstract

Temporomandibular disorders (TMD) are characterized by several signs and symptoms, such as pain and changes in the electrical activity of masticatory muscles. Considering that transcutaneous electrical nerve stimulation (TENS) is a resource indicated to promote analgesia, the objective of this study was to evaluate the effect of TENS on pain and electromyographic (EMG) activity of the jaw elevator muscles in TMD patients. This study evaluated 35 female volunteers: 19 TMD patients (mean age = 23.04 ± 3.5) and 16 normal subjects (mean age = 23.3 ± 3.0). Transcutaneous electrical nerve stimulation (conventional mode, 150 Hz) was applied once to each group for 45 minutes. Surface electromyography (gain of 100 times and 1 kHz sampling frequency) and the visual analogue scale (VAS) were applied before and immediately after TENS application. Both VAS data and root mean square (RMS) values were analyzed using Student's t-test. The TMD group, compared to the control group, showed higher EMG activity of the jaw elevator muscles at rest. No difference was observed between the groups regarding maximum voluntary clenching (MVC). In TMD patients, TENS reduced both pain and EMG activity of the anterior portion of the temporal muscle, increasing the activity of the masseter muscles during MVC. It is possible to conclude that a single TENS application is effective in pain reduction. However, it does not act homogeneously on the features of the electric activity of the muscles evaluated. DESCRIPTORS: Temporomandibular joint; Electromyography; Masticatory muscles; Transcutaneous electric nerve stimulation; Facial pain. RESUMO:A desordem temporomandibular (DTM) é caracterizada por diversos sinais e sintomas, como dor e alteração do sinal eletromiográfico dos músculos da mastigação. Considerando que a estimulação elétrica nervosa transcutânea (TENS) é um recurso indicado para promover analgesia, o objetivo deste trabalho foi avaliar o efeito da TENS na dor e na atividade eletromiográfica (EMG) dos músculos elevadores da mandíbula em indivíduos com DTM. Foram selecionados 35 voluntários do sexo feminino, 19 portadores de DTM (média de 23,04 anos ± 3,5) e 16 normais (média de 23,3 anos ± 3,0). A TENS (modo convencional, 150 Hz) foi aplicada uma vez em ambos os grupos, por 45 min. O exame EMG de superfície (ganho de 100 vezes e freqüência de amostragem de 1 kHz) e a escala visual analógica (EVA) foram realizados antes e imediatamente depois da aplicação da TENS. Os dados da EVA e os valores da "root mean square" (RMS) foram analisados pelo teste t de Student. Observou-se que, na situação de repouso, os indivíduos com DTM apresentam um aumento da atividade EMG dos músculos elevadores da mandí-bula em relação aos do grupo controle. Na contração voluntária máxima (CVM), não foram observadas diferenças entre os grupos. Nos portadores de DTM, a TENS reduziu a dor, a atividade EMG da porção anterior do músculo temporal e aumentou a atividade dos músculos masseteres durante a CVM. É possível concluir que apenas uma aplicação da TENS...

Propriedades clinimétricas da variável eletromiográfica duty factor para desordem temporomandibular

“…Silver chloride surface electrodes from EMG System of Brazil® (São José dos Campos, Brazil) were placed on volunteers after cleaning skin with cotton soaked in 70% ethanol. The silver bars were placed perpendicular to the muscle fibers in order to maximize signal capture and minimize noise interference (12) . The EMG signals were then captured from the masseter, anterior temporal and suprahyoid muscles during maximum voluntary contraction (MVC) of the jaw (Figure 1).…”

“…On finishing the EMG recording, conventional TENS was applied (symmetrical biphasic square waveforms, 150 Hz 20 µs, electrical paresthesia and 50% frequency modulation) for 45 minutes, stipulated by previous studies as sufficient time to generate analgesia (12) . Electrodes were placed on the masseter muscle and the anterior acoustic meatus (12) .…”

“…Several pain reduction techniques are used to treat TMD (4)(5)(6)(7)(8)(9)(10) . In physical therapy in particular, transcutaneous electric nerve stimulation (TENS) is one of the most utilized non-pharmacological analgesic resources (11) . Studies have demonstrated its effectiveness in promoting analgesia and reducing electromyographic muscle activity while resting (11) .…”

“…In physical therapy in particular, transcutaneous electric nerve stimulation (TENS) is one of the most utilized non-pharmacological analgesic resources (11) . Studies have demonstrated its effectiveness in promoting analgesia and reducing electromyographic muscle activity while resting (11) . In the literature, it has been shown that applying TENS in individuals with TMD produces some form of alteration in the activation patterns of masticatory muscles (12) .…”

“…Studies have demonstrated its effectiveness in promoting analgesia and reducing electromyographic muscle activity while resting (11) . In the literature, it has been shown that applying TENS in individuals with TMD produces some form of alteration in the activation patterns of masticatory muscles (12) . Researchers found a reduction in electrical activity of the muscles during the opening movement of the jaw after a TENS intervention, an indication that its pain inhibitory properties reduced the hyperactive reflex generated by pain in those muscles.…”