Perfil clínica y electromiográfico de las distrofias musculares en República Dominicana / Clinical and electromyographic profile of muscular dystrophies in the Dominican Republic

Introducción: Las distrofias musculares son trastornos miogénicos hereditarios caracterizados por una atrofia muscular progresiva y una debilidad de distribución y gravedad variable. La población de Republica Dominicana es fruto de una mezcla de etnias, haciéndola portadora de una herencia cromosómica y ADN diverso, siendo susceptibles a poder presentar cualquier desorden de carácter hereditario. Material y métodos: Con una muestra de 17 pacientes obtenidos entre septiembre 2019- marzo 2020, se realizó un estudio retrospectivo, descriptivo y transversal, en el cual se hizo una revisión de los expedientes de la clínica de miopatías en la consulta de neurología pediátrica del Hospital Infantil Doctor Robert Reid Cabral, para describir el perfil clínico de los pacientes con distrofia muscular y los hallazgos de electromiografía en los casos que la misma. Resultados: se encontró que la distribución de la edad correspondió a 5-9 años en un 53%, siendo el sexo masculino, el más frecuente. En el 70.59% presentaron antecedentes familiares de distrofia muscular. Los principales motivos de consulta fueron cansancio y caídas frecuentes. Conclusión: En los hallazgos de electromiografía, el porcentaje de pacientes que presentó esta prueba con alteraciones fue de 88.24% y sin alteraciones el 11.76%. Esto nos demuestra, la gran utilidad de dicho estudio en el diagnóstico de las distrofias musculares en países donde no se cuenta con estudio molecular, siendo una de las pruebas esenciales en el abordaje diagnóstico de los pacientes con sospecha clínica de dichas patologías.

Introduction: Muscular dystrophies are hereditary myogenic disorders characterized by progressive muscular atrophy and weakness of variable distribution and severity. The population of the Dominican Republic is the result of a mixture of ethnic groups, making it the bearer of a diverse chromosomal inheritance and DNA, being susceptible to presenting any hereditary disorder. Methods: With a sample of 17 patients obtained between September 2019-March 2020, a retrospective, descriptive and cross-sectional study, in which a review of the files of the myopathies clinic was made in the pediatric neurology consultation of the Children's Hospital Doctor Robert Reid Cabral, to describe the clinical profile of patients with muscular dystrophy and the electromyography findings in the cases with the same. Results: The age distribution corresponded to 5-9 years; 53%, being the masculines, the most frequent sex. In 70.59%, there was a family history of muscular dystrophy. The main reasons for consultation were fatigue and frequent falls. Conclusion: In the electromyography findings, the percentage of patients who presented this test with alterations was 88.24% and 11.76% without alterations. This result shows us the great utility of said study in the workup of muscular dystrophies in countries with no availabilities for molecular studies, being one of the essential tests in the diagnostic approach of patients with clinical suspicion of said pathologies.

Effect of M-wave Amplitude on Inter-evaluator Concordance and Number of Detected Innervation Zones in the Medial Gastrocnemius Using Multichannel Electromyography / Efecto de la Amplitud de la Onda M sobre la Concordancia entre Evaluadores y el Número de Zonas de Inervación Detectadas en el Gastrocnemio Medial Mediante Electromiografía Multicanal

SUMMARY: The Innervation Zones (IZ) correspond to clusters of neuromuscular junctions. The traditional method of locating IZs through voluntary muscle contractions may not be feasible in individuals with motor disorders. Imposed contractions by electrostimulation are an alternative. However, there is limited evidence regarding the factors that affect inter-evaluator concordance and the number of localized IZs when using imposed contraction. The main objective of this research was to determine the effect of the amplitude of compound motor action potentials (CMAPs) containing the M-wave on inter-evaluator agreement. As a secondary objective, was investigate the effect on the number of detected IZs. Twenty-four healthy volunteers (age: 21.2 ± 1.5years, weight: 67.4 ± 13.2kg, height: 1.68 ± 0.80m) participated in the study. Electrostimulation was applied to the tibial nerve to induce contraction of the medial gastrocnemius. The IZ were identified based on the M-wave recorded through multichannel electromyography. A receiver operating characteristic (ROC) analysis was conducted to assess sensitivity and specificity in detecting the IZs. Inter-rater agreement was evaluated using a two-way mixed effects test to determine the intraclass correlation coefficients (ICC). A p-value less than 0.05 was considered statistically significant. The ROC analysis revealed that for both evaluators, a specificity of 95% was achieved with an amplitude ≥30 %. The area under the ROC curve was 0.980 [0.964, 0.996], indicating a strong influence of CMAP amplitude on detection of IZs. The highest level of agreement (ICC = 0.788 [0.713, 0.844]) among the evaluators was observed with CMAP amplitudes equal to or greater than 80 % of the maximum M-wave. The findings of this study demonstrate that both the number and the inter-evaluator concordance for detecting IZs using imposed contractions are strongly influenced by the amplitude of the M-wave. Higher M-wave amplitudes were associated with improved concordance and increased IZ detection, making it crucial to standardize amplitude settings for reliable outcomes.

Las Zonas de Inervación (IZ) corresponden a grupos de uniones neuromusculares. El método tradicional para localizar IZs mediante contracciones musculares voluntarias puede no ser factible en personas con trastornos motores. Las contracciones impuestas mediante electro estimulación son una alternativa. Sin embargo, existe poca evidencia sobre los factores que afectan la concordancia entre evaluadores y el número de IZs localizadas al usar este tipo de contracciones. El objetivo de esta investigación fue determinar el efecto de la amplitud de los potenciales de acción motores compuestos (PAMCs) que contienen la onda M sobre la concordancia entre evaluadores. Como objetivo secundario, se investigó el efecto sobre el número de IZs detectadas. Veinticuatro voluntarios sanos (edad: 21.2 ± 1.5 años, peso: 67.4 ± 13.2 kg, altura: 1.68 ± 0.80 m) participaron en el estudio. Se aplicó electroestimulación al nervio tibial para inducir la contracción del gastrocnemio medial. Las IZs se identificaron según la onda M registrada mediante electromiografía multicanal. Se realizó un análisis de curva de las característica del receptor (ROC) para evaluar la sensibilidad y especificidad en la detección de las IZs. La concordancia entre evaluadores se evaluó utilizando una prueba de efectos mixtos de dos vías para determinar los coeficientes de correlación intraclase (ICC). Se consideró un valor de p menor que 0.05 como estadísticamente significativo. El análisis ROC reveló que para ambos evaluadores se logró una especificidad del 95% con una amplitud ≥30 %. El área bajo la curva ROC fue de 0.980 [0.964, 0.996], lo que indica una fuerte influencia de la amplitud del CMAP en la detección de las IZs. El nivel más alto de concordancia (ICC = 0.788 [0.713, 0.844]) entre los evaluadores se observó con amplitudes de CMAP iguales o mayores al 80 % de la onda M máxima. Los hallazgos de este estudio demuestran que tanto el número como la concordancia entre evaluadores para detectar IZs mediante contracciones impuestas están fuertemente influenciados por la amplitud de la onda M. Las amplitudes más altas de la onda M se asociaron con una concordancia mejorada y un aumento en la detección de IZs, lo que hace crucial estandarizar los ajustes de amplitud para obtener resultados confiables.

Repouso eletromiográfico dos músculos mastigatórios de pacientes com disfunção temporomandibular antes e após intervenção fonoaudiológica com e sem bandagem elástica / Electromyographic rest of the masticatory muscles of patients with temporomandibular disorders before and after speech therapy with and without elastic bandage / Resto electromiográfico de los músculos masticatorios de pacientes con trastornos temporomandibulares antes y después de logopedia con y sin venda elástica

Objetivo: A pesquisa tem por objetivo verificar os limiares de repouso eletromiográfico dos músculos masseter e temporal em pacientes com disfunção temporomandibular (DTM) antes e após intervenção fonoaudiológica com e sem a utilização de bandagem elástica terapêutica. Métodos: A coleta contou com 14 participantes do sexo feminino, com idade entre 18 e 40 anos, com diagnóstico de DTM muscular ou mista. As pacientes foram divididas entre dois grupos classificados em: pacientes com bandagem associada à terapia tradicional (CB) e grupo de terapia tradicional (SB). As pacientes inicialmente foram avaliadas pelo exame de eletromiografia de superfície nas situações de contração voluntária máxima e repouso, e após quatro semanas de intervenção, foi realizada nova avaliação com os mesmos instrumentos. A análise dos dados ocorreu de forma quantitativa e qualitativa. Resultados:No grupo SB o músculo masseter direito apresentou aumento dos valores de repouso com significância, foi observado que o mesmo ocorreu para todos os músculos deste grupo, influenciando no equilíbrio da musculatura ipsilateral e contralateral, no entanto sem evidência estatística. O grupo CB não demonstrou valores estatísticos significativos, porém qualitativamente os valores de repouso muscular diminuíram e equilibraram-se de forma contralateral. Conclusão: Não foram observadas mudanças estatisticamente significantes nos limiares eletromiográficos durante repouso dos músculos masseter e temporal em ambos os grupos. Qualitativamente houve aumento dos valores eletromiográficos após terapia manual tradicional em todos os músculos do grupo SB. Com relação ao grupo CB, houve diminuição dos valores do repouso eletromiográfico após terapia, embora sem evidências estatísticas. (AU)

Purpose: Objective: The research aims to verify the electromyographic rest thresholds of the masseter and temporal muscles in patients with temporomandibular disorders (TMD) before and after speech therapy intervention with and without the use of therapeutic elastic bandage. Methods: The collection included 14 female participants, aged between 18 and 40 years, who had a diagnosis of muscular or mixed TMD. The patients were divided into two groups: with traditional therapy (CB) bandage and traditional therapy (SB) only group. The patients underwent initial evaluation, as well as surface electromyography in situations of maximum voluntary contraction and rest and at the end of the four weeks of intervention, a new evaluation was performed with the same instruments. Data analysis occurred quantitatively and qualitatively. Results: In the SB group, the right masseter muscle showed a significant increase in resting values. It was observed that the same occurred for all muscles in this group, influencing the balance of the ipsilateral and contralateral muscles, although without statistical evidence. The CB group did not show statistically significant values, but qualitatively the muscle rest values decreased and balanced in a contralateral way. Conclusion: No statistically significant changes were observed in the resting electromyographic thresholds of the masseter and temporalis muscles in both groups. Qualitatively, there was an increase in electromyographic values after traditional manual therapy in all muscles in the SB group. Regarding the CB group, there was a decrease in electromyographic resting values after therapy, although without statistical evidence. (AU)

Objetivo: La investigación tiene como objetivo verificar los umbrales electromiográficos de reposo de los músculos masetero y temporal en pacientes con trastornos temporomandibulares (TMD) antes y después de la terapia del habla con y sin el uso de venda elástica terapéutica. Métodos: La colección incluyó a 14 participantes mujeres, con edades entre 18 y 40 años, diagnosticadas con TTM muscular o mixta. Los pacientes fueron divididos en dos grupos clasificados en: pacientes con vendaje asociado a terapia tradicional (CB) y grupo de terapia tradicional (SB). Los pacientes fueron inicialmente evaluados mediante electromiografía de superficie en situaciones de máxima contracción voluntaria y reposo, luego de cuatro semanas de intervención se realizó una nueva evaluación con los mismos instrumentos. El análisis de datos se llevó a cabo cuantitativa y cualitativamente. Resultados: En el grupo SB, el músculo masetero derecho presentó un aumento significativo en los valores de reposo, se observó que lo mismo ocurrió para todos los músculos de este grupo, influyendo en el equilibrio de los músculos ipsilaterales y contralaterales, sin embargo, sin evidencia estadística. El grupo CB no mostró valores estadísticamente significativos, pero cualitativamente los valores de descanso muscular disminuyeron y se equilibraron contralateralmente. Conclusión: No se observaron cambios estadísticamente significativos en los umbrales electromiográficos en reposo de los músculos masetero y temporal en ambos grupos. Cualitativamente, hubo un aumento de los valores electromiográficos después de la terapia manual tradicional en todos los músculos del grupo SB. En cuanto al grupo CB, hubo una disminución de los valores electromiográficos de reposo después de la terapia, aunque sin evidencia estadística. (AU)

Investigation of the Neuro-Regenerative Effects of Bioresonance and Magnetotherapy in Sciatic Nerve Damage-Induced Rats / Investigación de los Efectos Neurorregenerativos de Biorresonancia y Magnetoterapia en Ratas Inducidas por Daño del Nervio Ciático

SUMMARY: Peripheral nerve damage is a significant clinical problem that can lead to severe complications in patients. Regarding the regeneration of peripheral nerves, it is crucial to use experimental animals' nerves and use different evaluation methods. Epineural or perineural suturing is the gold standard in treating sciatic nerve injury, but nerve repair is often unsuccessful. This study aimed to investigate the neuroregenerative effects of magnetotherapy and bioresonance in experimental animals with sciatic nerve damage. In this study, 24 female Wistar rats were divided into 7 groups (n=6) as follows: Group 1 (Control), Group 2 (Axonotmesis control), Group 3 (Anastomosis control), Group 4 (Axonotmesis + magnetotherapy), Group 5 (Anastomosis + magnetotherapy), Group 6 (Axonotmesis + bioresonance), Group 7 (Anastomosis + bioresonance). Magnetotherapy and bioresonance treatments were applied for 12 weeks. Behavioural tests and EMG tests were performed at the end of the 12th week. Then the rats were sacrificed, and a histopathological evaluation was made. The statistical significance level was taken as 5 % in the calculations, and the SPSS (IBM SPSS for Windows, ver.21) statistical package program was used for the calculations. Statistically significant results were obtained in animal behaviour tests, EMG, and pathology groups treated with magnetotherapy. There was no statistically significant difference in the groups treated with bioresonance treatment compared to the control groups. Muscle activity and nerve repair occurred in experimental animals with acute peripheral nerve damage due to 12 weeks of magnetotherapy, and further studies should support these results.

El daño a los nervios periféricos es un problema clínico importante que puede conducir a complicaciones graves en los pacientes. En cuanto a la regeneración de los nervios periféricos, es crucial utilizar los nervios de los animales de experimentación y diferentes métodos de evaluación. La sutura epineural o perineural es el gold estándar en el tratamiento de lesiones del nervio ciático, pero la reparación del nervio a menudo no tiene éxito. Este estudio tuvo como objetivo investigar los efectos neuroregenerativos de la magnetoterapia y la biorresonancia en animales de experimentación con daño del nervio ciático. En el estudio, 24 ratas hembras Wistar se dividieron en 7 grupos (n=6) de la siguiente manera: Grupo 1 (Control), Grupo 2 (Control de axonotmesis), Grupo 3 (Control de anastomosis), Grupo 4 (Axonotmesis + magnetoterapia), Grupo 5 (Anastomosis + magnetoterapia), Grupo 6 (Axonotmesis + biorresonancia), Grupo 7 (Anastomosis + biorresonancia). Se aplicaron durante 12 semanas tratamientos de magnetoterapia y biorresonancia. Las pruebas de comportamiento y las pruebas de EMG se realizaron al final de la semana 12. Luego se sacrificaron las ratas y se realizó una evaluación histopatológica. El nivel de significación estadística se tomó como 5 % en los cálculos, y se utilizó el programa de paquete estadístico SPSS (IBM SPSS para Windows, ver.21). Se obtuvieron resultados estadísticamente significativos en pruebas de comportamiento animal, EMG y grupos de patología tratados con magnetoterapia. No hubo diferencia estadísticamente significativa en los grupos con tratamiento de biorresonancia en comparación con los grupos controles. La actividad muscular y la reparación nerviosa, se produjeron en animales de experimentación con daño nervioso periférico agudo, debido a 12 semanas de magnetoterapia.Estudios adicionales deberían respaldar estos resultados.

Diagnostic Contradictions in Carpal Tunnel Syndrome / Contradições diagnósticas na síndrome do túnel do carpo

Abstract Objective Given the divergence of opinions on the need for complementary tests such as ultrasonography (US) and electroneuromyography (ENMG) for the diagnosis of carpal tunnel syndrome (CTS), we aimed to elucidate which of them presents greater accuracy for the confirmation of the presence or not of this condition. Methods A total of 175 patients from a hand surgery outpatient clinic were clinically evaluated, and the results of clinical trials (Tinel, Phalen and Durkan), US (normal or altered), and ENMG (normal, mild, moderate and severe) were noted, crossed, and submitted to a statistical analysis to verify the agreement between them. Results with the sample had a mean age of 53 years, with a prevalence of female patients (159 cases). Of the patients with positive clinical test, 43.7% had normal US and 41.7% had no alterations on the ENMG. Negative results were found on the Tinel in 46.9%, on the Phalen in 47.4%, and on the Durkan in 39.7%. In the crossing between the results of the ENMG and those of the other diagnostic methods, there was little statistical agreement between them. Conclusion There was no agreement between the results of the clinical examinations, the US and the ENMG in the diagnosis of CTS, and there is no clinical or complementary examination for CTS that accurately determines the therapeutic approach. Level of Evidence IV, Case Series.

Resumo Objetivo Diante da divergência sobre a necessidade de exames complementares, como ultrassonografia (US) e eletroneuromiografia (ENMG) para o diagnóstico da síndrome do túnel do carpo (STC), objetivamos elucidar qual deles apresenta maior precisão na confirmação da presença ou não desta afecção. Métodos Um total de 175 pacientes de um ambulatório de cirurgia da mão foram avaliados clinicamente, e os resultados dos testes clínicos (Tinel, Phalen e Durkan), da US (normal ou alterada) e da ENMG (normal, leve, moderada e grave) foram anotados, cruzados, e submetidos a análise estatística para verificar a concordância entre eles. Resultados A idade média da amostra era de 53 anos, sendo prevalente o sexo feminino (159 casos). Dos pacientes com teste clínico positivo, 43,7% apresentavam US normal, e 41,7%, ENMG sem alterações. Foram encontrados resultados negativos no Tinel em 46,9% no Phalen em 47,4%, e no Durkan em 39,7%. No cruzamento entre a ENMG e os demais métodos diagnósticos, houve pouca concordância estatística. Conclusão Não houve concordância entre os resultados dos exames clínicos, da US e da ENMG no diagnóstico da STC, e não há exame clínico ou complementar para STC que determine a conduta terapêutica com precisão. Nível de Evidência IV, Série de Casos.

Electromyographic signals and the starting threshold voltage of orbicularis oris muscle in healthy rhesus monkeys / 中华耳鼻咽喉头颈外科杂志

Objective: To investigate the characteristics of electromyography (EMG) signals and the starting threshold voltages of the orbicularis oris muscles (OOM) in healthy rhesus monkeys under different muscle movement conditions. Methods: The EMG signals and the starting threshold voltages at different time points in 4 healthy rhesus monkeys were acquired and recorded with EMG device and evoked potentiometer. The voltage amplitude variation of EMG signals was analyzed, and the voltage amplitude range of EMG signals at the beginning of OOM contraction was established. The data were statistically analyzed by one-way ANOVA. Results: The EMG of OOM in healthy monkeys in the quiet, natural and continuous mouth-closed state was linear and relatively stable, and the absolute value fluctuated between 15 and 50 μV. The EMG waveform increased rapidly during the natural lip contraction movement, and its amplitude fluctuated greatly, with the highest absolute value of the peak value reaching hundreds of microvolts. The amplitude of EMG induced by continuous mouth closure was more than thousands of microvolts. There was no significant difference in EMG amplitudes of OOM in the healthy rhesus monkey under quiet and continuous lip closure at different time points (P>0.05). There was no significant difference in threshold voltages in the state of natural lip contraction of bilateral OOM at different time points (average range: 57.17-57.47 μV) in the healthy rhesus monkeys (P>0.05). There was no significant difference in threshold voltages of OOM induced by bilateral OOM at different time points(average range: 55.38-55.99 μV) in the healthy rhesus monkeys(P>0.05). There were significant differences in the absolute values of EMG amplitudes of OOM between the three lip movement modes: (30.67±8.72) μV in quiet and natural continuous lip closure (475.12±54.72) μV in natural lip contraction, and (921.22±312.79) μV in the induced persistent lip closure, with t values of -8.48, -9.35 and -5.01 respectively, all P<0.001. Conclusions: The EMG signals of OOM show different characteristics under different muscle movement conditions, which can be used as a basis for computer to judge and recognize the movement conditions of OOM. The upper limits of the EMG threshold voltage values of OOM under different motion states are 55-60 μV.

Evaluation of ankle joint protection effect of parachute ankle brace on paratrooper landing / 中华劳动卫生职业病杂志

Objective: To study the protective effect of parachute ankle brace on ankle joint during simulated parachuting landing. Methods: In August 2021, 30 male paratroopers were selected as the test subjects by simple random sampling method. They jumped from the 1.5 m and 2.0 m height platforms respectively with and without parachute ankle brace, and landed on the sandy ground in a semi-squat parachute landing position. The experiment was divided into 1.5 m experimental group and control group and 2.0 m experimental group and control group. Angle sensor and surface electromyograph were used to measure and analyze the coronal tilt range of the ankle joint and the percentage of maximal voluntary contraction (MVE%) of the muscles around the ankle joint, respectively, to evaluate the protective effect of the parachute ankle brace. Results: At the same height, the tilt range of coronal plane of ankle in experimental group was significantly reduced compared with control group, and the difference was statistically significant (P<0.05). Under the same protection state, the tilt range of the coronal plane of the ankle in the 1.5 m group was significantly reduced compared with that in the 2.0 m group, and the difference was statistically significant (P<0.05). The coronal plane inclination range of the ankle in 2 m experimental group was significantly lower than that in 1.5 m control group, and the difference was statistically significant (P<0.05). Compared with 1.5 m control group, MVE% of right tibialis anterior muscle and bilateral lateral gastrocnemius decreased in 1.5 m experimental group, while MVE% of bilateral peroneus longus increased, with statistical significance (P<0.05). Compared with 2.0 m control group, the MVE% of bilateral tibialis anterior muscle and right lateral gastrocnemius decreased in 2.0 m experimental group, while the MVE% of bilateral peroneus longus increased, with statistical significance (P<0.05). The MVE% of bilateral tibialis anterior muscle, bilateral lateral gastrocnemius muscle and right peroneus longus muscle in 1.5 m experimental group decreased compared with 2.0 m experimental group, and the differences were statistically significant (P<0.05). Compared with 2.0 m control group, the MVE% of bilateral tibialis anterior muscle, right lateral gastrocnemius muscle and right peroneus longus muscle in 1.5 m control group decreased, and the differences were statistically significant (P<0.05) . Conclusion: Wearing parachute ankle brace can effectively limit the coronal plane inclination range of ankle joint, improve the stability of ankle joint and reduce the load on the muscles around ankle joint by landing. Reducing the height of the jumping platform can reduce the coronal plane incline range of the ankle and the muscle load around the ankle during landing.

Evaluation of Muscle Fatigue in Spinal Surgery Instruments Based on sEMG-JASA / 中国医疗器械杂志

Based on the joint analysis of EMG spectrum and amplitude method (JASA), a study on muscle fatigue assessment of spinal surgical instruments based on surface EMG signals was carried out, and a comparative evaluation of the operating comfort before and after the optimization of spinal surgical instruments was completed. A total of 17 subjects were recruited to collect the surface EMG signals of their brachioradialis and biceps. Five surgical instruments before and after optimization were selected for data comparison, and the operating fatigue time proportion of each group of instruments under the same task was calculated based on the RMS and MF eigenvalues. The results showed that when completing the same operation task, the operation fatigue time of the surgical instruments before optimization was significantly higher than that after optimization (P<0.05); there was no significant difference in the fatigue status of brachioradialis and biceps when operating the same instrument (P>0.05). These results provide objective data and reference for the ergonomic design of surgical instruments and fatigue damage protection.

Correlation between Elbow Flexor Muscle Strength and Needle Electromyography Parameters after Musculocutaneous Nerve Injury / 法医学杂志

OBJECTIVES@#To explore the changes of elbow flexor muscle strength after musculocutaneous nerve injury and its correlation with needle electromyography (nEMG) parameters.@*METHODS@#Thirty cases of elbow flexor weakness caused by unilateral brachial plexus injury (involving musculocutaneous nerve) were collected. The elbow flexor muscle strength was evaluated by manual muscle test (MMT) based on Lovett Scale. All subjects were divided into Group A (grade 1 and grade 2, 16 cases) and Group B (grade 3 and grade 4, 14 cases) according to their elbow flexor muscle strength of injured side. The biceps brachii of the injured side and the healthy side were examined by nEMG. The latency and amplitude of the compound muscle action potential (CMAP) were recorded. The type of recruitment response, the mean number of turns and the mean amplitude of recruitment potential were recorded when the subjects performed maximal voluntary contraction. The quantitative elbow flexor muscle strength was measured by portable microFET 2 Manual Muscle Tester. The percentage of residual elbow flexor muscle strength (the ratio of quantitative muscle strength of the injured side to the healthy side) was calculated. The differences of nEMG parameters, quantitative muscle strength and residual elbow flexor muscle strength between the two groups and between the injured side and the healthy side were compared. The correlation between elbow flexor manual muscle strength classification, quantitative muscle strength and nEMG parameters was analyzed.@*RESULTS@#After musculocutaneous nerve injury, the percentage of residual elbow flexor muscle strength in Group B was 23.43% and that in Group A was 4.13%. Elbow flexor manual muscle strength classification was significantly correlated with the type of recruitment response, and the correlation coefficient was 0.886 (P<0.05). The quantitative elbow flexor muscle strength was correlated with the latency and amplitude of CMAP, the mean number of turns and the mean amplitude of recruitment potential, and the correlation coefficients were -0.528, 0.588, 0.465 and 0.426 (P<0.05), respectively.@*CONCLUSIONS@#The percentage of residual elbow flexor muscle strength can be used as the basis of muscle strength classification, and the comprehensive application of nEMG parameters can be used to infer quantitative elbow flexor muscle strength.

Modulation of motor responses and neural activities with transcranial ultrasound stimulation based on closed-loop control / 生物医学工程学杂志

Closed-loop transcranial ultrasound stimulation technology is based on real-time feedback signals, and has the potential for precise regulation of neural activity. In this paper, firstly the local field potential (LFP) and electromyogram (EMG) signals of mice under different intensities of ultrasound stimulation were recorded, then the mathematical model of ultrasound intensity and mouse LFP peak/EMG mean was established offline based on the data, and the closed-loop control system of LFP peak and EMG mean based on PID neural network control algorithm was simulated and built to realize closed-loop control of LFP peak and EMG mean of mice. In addition, using the generalized minimum variance control algorithm, the closed-loop control of theta oscillation power was realized. There was no significant difference between the LFP peak, EMG mean and theta power under closed-loop ultrasound control and the given value, indicating a significant control effect on the LFP peak, EMG mean and theta power of mice. Transcranial ultrasound stimulation based on closed-loop control algorithms provides a direct tool for precise modulation of electrophysiological signals in mice.

Design and Experimental Research of Synchronous Acquisition System of EMG and Blood Oxygen Signal / 中国医疗器械杂志

In this study, a surface electromyography (sEMG) and blood oxygen signal real-time monitoring system is designed to explore the changes of physiological signals during muscle fatigue, so as to detect muscle fatigue. The analysis method of sEMG and the principle of blood oxygen detection are respectively introduced, and the system scheme is expounded. The hardware part of the system takes STM32 as the core. Conditioning module composition; blood oxygen signal acquisition is based on near infrared spectroscopy (NIRS), specifically including light source, light source driving, photoelectric conversion, signal conditioning and other modules. The system software part is based on the real-time uC/OS-III software system. The characteristic parameters of sEMG were extracted by isometric contraction local muscle fatigue experiment; the relative changes of oxyhemoglobin (HbO2) and deoxyhemoglobin (Hb) were calculated in the forearm blocking experiment, thereby verifying that the system collects two signals effectiveness.

Normalization of the electromyographic signals of masticatory muscles during non-habitual chewing activity

There is no consensus on the most appropriate method for normalizing electromyography (EMG) signals from masticatory muscles during isotonic activity. Aim: To analyze the best method for data processing of the EMG signal of the masticatory muscles during isotonic activity (non-habitual chewing), comparing raw data and different types of normalization. Methods: This is a cross-sectional study. Women aged between 18 and 45 years were selected. Anthropometric data were collected (age, height, body mass index ­ BMI, masticatory preference) as well as EMG signal (root mean square ­ RMS) data for the anterior temporal and masseter bilaterally, and for the suprahyoid muscles, during isotonic (non-habitual chewing) and isometric tasks. EMG data were processed offline using Matlab® Software. The normalization of the EMG signal was carried out using the 2nd masticatory cycle, chosen at random, of the 20 cycles collected, the maximum RMS value, and the maximum voluntary contraction (MVC). To analyze the best method of data processing for the isotonic data, the coefficient of variation (CV) was calculated. Descriptive data analysis was adopted, using the mean and standard deviation. ANOVA with repeated measures was used to detect significant differences between the methods of normalization. Statistical significance was set at 5% (α<0.05). Results: The final sample of this research was composed of 86 women. The volunteers presented an average age of 27.83±7.71 years and a mean BMI of 22.85±1.91 Kg/m2. Regarding masticatory preference, 73.25% reported the right side, and 26.75% the left side. Considering the comparison between the methods, the %CV measure of the 2nd cycle showed the lowest variation coefficient during biting for all the muscles from the raw data, RMS Max, and MVC (p=0.001, p=0.003, and p=0.001 respectively). Conclusion: In conclusion, for non-habitual chewing activity, the results of this study recommend data processing using normalization with the second cycle during chewing

Effect of low-level LASER therapy versus CAD/CAM Michigan splint on patients with Temporomandibular Muscle Disorders: a randomized clinical trial / Efeito da terapia LASER de baixa potência versus placa de Michigan CAD/CAM em pacientes com Distúrbios Temporomandibulares musculares: um ensaio clínico randomizado

Objective: This study aimed to evaluate the efficacy and sustainability of using low level LASER therapy and CAD/CAM Michigan splint on improving the range of mandibular movements, muscle activity and reducing the pain. Material and Methods: 56 female patients were randomly divided into two groups. Group A: Patients received applications of low-level LASER therapy using semiconductor InGaAsp diode LASER type 940 nm with continuous mode of operation, applied for 180 sec per session for 12 sessions. Group B: Patients received Michigan splint of 2 mm thickness constructed on their upper teeth, the splint was 3D digitally printed. Electromyography was used to evaluate muscle activity, visual analogue scale was used to evaluate the pain intensity, ARCUS digma facebow was used to evaluate range of mandibular movements, and maximum mouth opening was taken using a millimeter ruler. They were measured before the beginning of the treatment, and at three and six month follow-up periods. Results: The results revealed that both low-level LASER therapy and Michigan splint reduce the myofascial pain, improved the range of the mandibular movements, and the muscles activity, but the effect of the low-level LASER therapy was more profound and sustainable. After 6 months from the beginning of the treatment, changes in masseter muscle activity (P= 0.001; effect size= 1.757), pain intensity (P= 0.003; effect size= 3), and range of mandibular movement (P= 0.001, effect size= 1.729) differed significantly between the two groups. Conclusions: Low-level LASER therapy had a better and more sustainable effect on reducing the pain intensity and improving the muscle activity as well as the mandibular movement when compared to Michigan splint (AU)

Objetivo: Este estudo teve como objetivo avaliar a eficácia e a durabilidade do uso da terapia LASER de baixa potência e da placa de Michigan CAD/CAM na melhora da amplitude dos movimentos mandibulares, atividade muscular e redução da dor. Material e Métodos: 56 pacientes do sexo feminino foram divididos aleatoriamente em dois grupos. Grupo A: os pacientes receberam aplicações de terapia LASER de baixa potência utilizando diodo semicondutor InGaAsp LASER tipo 940 nm em modo contínuo de operação, aplicado por 180 segundos por sessão durante 12 sessões. Grupo B: os pacientes receberam a placa de Michigan com uma espessura de 2 mm confeccionada sobre a arcada superior, a placa foi impressa digitalmente em 3D. A eletromiografia foi utilizada para avaliar a atividade muscular, a escala visual analógica foi utilizada para avaliar a intensidade da dor, o arco facial ARCUS digma foi utilizado para determinar a amplitude dos movimentos mandibulares e a abertura máxima da boca foi medida com uma régua milimétrica. Todas as medidas foram realizadas antes do início do tratamento e nos períodos de acompanhamento de três e seis meses. Resultados: Os resultados revelaram que tanto a terapia LASER de baixa potência como a placa de Michigan reduziram a dor miofascial, aumentaram a amplitude dos movimentos mandibulares e melhoraram a atividade muscular, mas o efeito da terapia LASER de baixa potência foi mais profundo e duradouro. Após 6 meses do início do tratamento, as alterações na atividade do músculo masseter (P= 0. 001; tamanho do efeito= 1,757), intensidade da dor (P= 0,003; tamanho do efeito= 3), e amplitude de movimento mandibular (P= 0,001, tamanho do efeito= 1,729) diferiram significativamente entre os dois grupos. Conclusão: A terapia com LASER de baixa potência teve um efeito melhor e mais duradouro na redução da intensidade da dor e na melhora da atividade muscular, bem como do movimento mandibular, quando comparada à placa de Michigan(AU)

Is there an association between quadriceps muscle endurance and performance on activities of daily living in individuals with COPD? / Existe associação entre a resistência muscular do quadríceps e o desempenho nas atividades da vida diária em indivíduos com DPOC?

Abstract Introduction Chronic obstructive pulmonary disease (COPD) is characterized by limited airflow associated with inflammatory response and systemic manifestations, such as dyspnea, as well as physical inactivity and intolerance to exercise. The sum of these changes can lead to peripheral muscle fatigue and exert an impact on the performance of activities of daily living (ADL). Objective To investigate the possible association between peripheral muscle fatigue and performance on ADL in individuals with COPD, and to compare the results to those of healthy age-matched individuals. Methods Individuals with a diagnosis of COPD and healthy volunteers aged 60 years or older were submitted to evaluations of peripheral muscle fatigue (using surface electromyography) and performance on the Glittre-ADL test. Results Nine individuals with COPD and ten controls were evaluated. Median isometric quadriceps contraction time was 72 [38] and 56 [51] seconds, respectively. Execution time on the ADL test was 6.1 [4] and 3.6 [1.3] minutes for COPD and control group respectively, with a significant difference between groups (p < 0.05). However, no significant correlation was found between the evaluations. Conclusion No association was found between quadriceps muscle fatigue and performance on ADL in the sample studied. In the intergroup comparison, the individuals with COPD exhibited worse ADL time execution, but no significant difference was found regarding quadriceps muscle fatigue.

Resumo Introdução A doença pulmonar obstrutiva crônica (DPOC) é caracterizada por fluxo aéreo limitado associado à resposta inflamatória e manifestações sistêmicas, como dispneia, além de inatividade física e intolerância ao exercício. A soma dessas alterações pode levar à fadiga muscular periférica e exercer impacto no desempenho das atividades de vida diária (AVD). Objetivo Investigar a possível associação entre fadiga muscular periférica e desempenho em AVD em indivíduos com DPOC e comparar os resultados com indivíduos saudáveis da mesma faixa etária. Métodos Indivíduos com diagnóstico de DPOC e voluntários saudáveis com idade igual ou superior a 60 anos foram submetidos a avaliações de fadiga muscular periférica (por meio de eletromiografia de superfície) e desempenho no teste Glittre-ADL. Resultados Foram avaliados nove indivíduos com DPOC e dez controles. O tempo médio de contração isométrica do quadríceps foi de 72 [38] e 56 [51] segundos, respectivamente. O tempo de execução do teste de AVD foi de 6,18 [4,09] e 3,67 [1,3] minutos para DPOC e grupo controle, respectivamente, com diferença significativa entre os grupos (p < 0,05). No entanto não encontrou-se correlação significativa entre as avaliações. Conclusão Não encontrou-se associação entre a fadiga muscular do quadríceps e o desempenho nas AVD na amostra estudada. Na comparação intergrupos, os indivíduos com DPOC apresentaram pior tempo de execução das AVD, mas não encontrou-se diferença significativa em relação à fadiga muscular do quadríceps.

Maximum bilateral bite strength and RMS EMG for the diagnosis of myogenic TMD

Aim: The study aimed to evaluate the accuracy of the maximum bilateral molar bite force and the Root Mean Square (RMS) Electromyography (EMG) index of the masticatory muscles in the maximum bilateral molar bite (MMBMax) of women with myogenic Temporomandibular Disorder (TMD) and asymptomatic. Methods: This is a cross-sectional study, composed of 86 women allocated to the TMD Group (n=43) and Control Group (n=43) diagnosis through the Diagnostic Criteria for Temporomandibular Disorders. The maximum bilateral molar bite force was evaluated using a bite dynamometer and the RMS EMG index of the masticatory muscles (anterior temporalis, masseter) during 5 seconds of the MMBMax task. Student t-test was used for data comparison between accuracy of the bite force and RMS EMG of masticatory muscles during the MMBMax. Results: The maximum bilateral molar bite force showed high accuracy (AUC=0.99) for the diagnosis of women with myogenic TMD and asymptomatic women, and the RMS EMG index evaluated during the MMBMax showed a moderate level of accuracy for all masticatory muscles (AUC=0.70 to 0.75). Conclusion: The bilateral bite dynamometer with a surface EMG during bilateral bite can be used to diagnose TMD in young women

Pseudo-orthostatic tremor as a manifestation of vitamin B12 deficiency: A case report

@#Vitamin B12 deficiency has long been known to present with various neurological manifestations, but only rarely presents as movement disorders, especially in adults. We present the case of a 30-year-old vegan male presenting with tremors on both legs when standing which was relieved by vitamin B12 supplementation. To the best of our knowledge, this is the first documented case of slow orthostatic tremor or pseudo-orthostatic tremor caused by vitamin B12 deficiency.

Sincronización entre la videodeglución y la electromiografía de superficie en pacientes con afectación neurológica y síntomas de disfagia / Synchronization between videofluoroscopic swallowing study and surface electromyography in patients with neurological involvement presenting symptoms of dysphagia

Introducción. La disfagia se define como la dificultad para movilizar la comida desde la boca hasta el estómago. La prueba diagnóstica para esta condición es la videofluoroscopia, la cual no es totalmente inocua pues utiliza radiación ionizante. La electromiografía de superficie registra la actividad eléctrica de los músculos de manera no invasiva, por lo que puede considerarse como una alternativa para evaluar la deglución y estudiar la disfagia. Objetivo. Evaluar la relación entre los tiempos relativos de activación de los músculos implicados en la fase oral y faríngea de la deglución, con los movimientos registrados durante la videofluoroscopia. Materiales y métodos. Se analizaron las señales de la electromiografía de superficie de 10 pacientes neurológicos con síntomas de disfagia, captadas en forma simultánea con la videofluoroscopia. Se suministraron 5 ml de yogur y 10 ml de agua, y 3 g de galleta. Se estudiaron bilateralmente los grupos musculares maseteros, suprahioideos e infrahioideos. Se analizó el paso del bolo por la línea mandibular, las valleculas y el músculo cricofaríngeo, correlacionándolo con el tiempo inicial y el final de la activación de cada uno de los grupos musculares. Resultados. El tiempo promedio de la fase faríngea fue de 0,89 ± 0,12 s. En la mayoría de los casos, hubo activación muscular antes del paso por la línea mandibular y las valleculas. La terminación de la actividad muscular parece corresponder al momento en que se completa el paso del bolo alimenticio por el músculo cricofaríngeo. Conclusión. Se determinaron los tiempos de actividad muscular, la duración de la fase faríngea y la secuencia de la activación de los grupos musculares involucrados en la deglución, mediante electromiografía de superficie, validada con la videofluoroscopia.

Introduction: Dysphagia is defined as the difficulty in transporting food and liquids from the mouth to the stomach. The gold standard to diagnose this condition is the videofluoroscopic swallowing study. However, it exposes patients to ionizing radiation. Surface electromyography is a non-radioactive alternative for dysphagia evaluation that records muscle electrical activity during swallowing. Objective: To evaluate the relationship between the relative activation times of the muscles involved in the oral and pharyngeal phases of swallowing and the kinematic events detected in the videofluoroscopy. Materials and methods: Electromiographic signals from ten patients with neurological involvement who presented symptoms of dysphagia were analyzed simultaneously with videofluoroscopy. Patients were given 5 ml of yogurt, 10 ml of water, and 3 g of crackers. Masseter, suprahyoid, and infrahyoid muscle groups were studied bilaterally. The bolus transit through the mandibular line, vallecula, and the cricopharyngeus muscle was analyzed in relation to the onset and offset times of each muscle group activation. Results: The average time of the pharyngeal phase was 0.89 ± 0.12 s. Muscle activation was mostly observed prior to the bolus transit through the mandibular line and vallecula. The end of the muscle activity suggested that the passage of the bolus through the cricopharyngeus muscle was almost complete. Conclusion: The muscle activity times, duration of the pharyngeal phase, and sequence of the muscle groups involved in swallowing were determined using sEMG validated with the videofluoroscopic swallowing study.

Masticatory function according to body mass index: part II: electromyographic analysis / Función masticatoria según índice de masa corporal: parte II: análisis electromiográfico

Introduction: The objective of this study was to explore the electrical activity of the superficial muscles of mastication required to exert unilateral maximum bite force in subjects with different body mass index. Material and Methods: A cross-sectional observational study was conducted with a sample of 21 participants with an average age of 22.9 ± 3.5 years who were classified according to their body mass index, forming three study groups: normal weight (18.5-24.9), overweight (25-29.9) and obesity (≥30), with seven participants each. Through surface electromyography, the superficial muscles of mastication during right and left maximum bite force were evaluated. Results: No statistically significant differences in the maximum bite force were observed between the study groups. The data obtained from the electromyographic analysis of the superficial muscles of mastication demonstrate a trend indicating that subjects with a normal body mass index similarly activate the muscles on each side when performing a maximum bite force on a particular side, while overweight or obese subjects demonstrated significantly greater activation of the temporalis muscle associated with the side where the maximal bite force is performed. Conclusion: Our findings suggest that the maximum bite force is not influenced by body mass index and that during the performance of a maximum bite force subjects with increased body mass index present a greater activation of the temporalis muscle associated with the side where the maximum bite force was performed.

Introducción: El objetivo de este estudio fue explorar la actividad eléctrica de los músculos superficiales de la masticación, necesarios para ejercer la máxima fuerza de mordida unilateral, en sujetos con diferente índice de masa corporal. Material y Métodos: Se realizó un estudio observacional de corte transversal con una muestra de 21 participantes con una edad promedio de 22.9 ± 3.5 años, quienes fueron clasificados de acuerdo a su índice de masa corporal, formando tres grupos de estudio: peso normal (18,5-24,9), sobrepeso (25,0-29,9) y obesidad (≥30.0), con siete participantes cada uno. La electromiografía de superficie evaluó los músculos superficiales de la masticación durante la fuerza de mordida máxima derecha e izquierda. Resultados: No se observaron diferencias estadísticamente significativas en la fuerza de mordida máxima entre los grupos de estudio. Los datos obtenidos del análisis electromiográfico de los músculos superficiales de la masticación demuestran una tendencia que indica que los sujetos con un índice de masa corporal normal activan de manera similar los músculos de cada lado cuando ejercen la fuerza de mordida máxima en un lado en particular. mientras que los sujetos con sobrepeso u obesos demostraron una activación significativamente mayor del músculo temporal asociado con el lado donde se realiza la fuerza máxima de mordida. Conclusión: Nuestros hallazgos sugieren que la fuerza de mordida máxima no está influenciada por el índice de masa corporal y que durante la realización de una fuerza de mordida máxima los sujetos con índice de masa corporal aumentado presentan una mayor activación del músculo temporal asociado al lado donde se realizó la fuerza de mordida máxima.

Correlação entre ausculta cervical e eletromiografia de superfície na fase faríngea da deglutição / Correlation between cervical auscultation and electromyography in the pharyngeal phase of swallowing / Correlación entre auscultación cervical y electromiografía de superficie en la fase faríngea de la deglución

Objetivo: Correlacionar os dados acústicos da ausculta cervical com a atividade elétrica dos músculos envolvidos na fase faríngea da deglutição. Métodos: Trata-se de um estudo observacional, transversal, de abordagem quantitativa, aprovado em janeiro pelo CEP/UFSCPA (número 1.389.050). Todos os participantes do estudo assinaram o termo de consentimento livre e esclarecido. A fase faríngea da deglutição foi avaliada por meio de ausculta cervical e eletromiografia de superfície. Os indivíduos ingeriram 90 ml de água. Os dados da ausculta foram transferidos para o DeglutiSom® software, a duração e amplitude da atividade eletromiográfica foram mensuradas durante a deglutição com aparelho de eletromiografia de superfície Miotec®. O nível de significância adotado foi de 5%. Resultados:Cinquenta e sete mulheres participaram deste estudo. A média de idade foi de 23,4 anos. Ressalta-se que quanto maior a frequência média do pico da ausculta, menor é a média do pico do músculo supra-hióideo e quanto maior a intensidade, maior é o pico, assim como a média dos picos supra-hióideos. Foi possível demonstrar que o pico de atividade do músculo supra-hióideo foi significativamente maior do que o pico de atividade do músculo infra-hióideo para a deglutição de 90 ml de água. Conclusão:Os parâmetros acústicos da deglutição em indivíduos saudáveis estão correlacionados com a atividade elétrica dos músculos envolvidos na fase faríngea da deglutição.

Objective: Correlate the acoustic data of cervical auscultation to the electrical activity of the muscles involved in the pharyngeal phase of swallowing. Methods: This is an observational, cross-sectional study involving a quantitative approach and was approved on January by CEP/UFSCPA (number 1.389.050). All participants of the study signed an informed consent form. The pharyngeal phase of swallowing was assessed by employing auscultation and surface electromyography. Individuals ingested 90 ml of water. The auscultation data were transferred to DeglutiSom® software, the duration and amplitude of electromyographic activity was measured during swallowing using a Miotec® surface electromyography device. The level of significance adopted was 5%. Results: Fifty-seven women participated in this study. The average age was 23.4 years on average. It must be highlighted that the greater the average peak frequency of auscultation, lower was the average peak of the suprahyoid muscle and the greater the intensity, the greater was the peak, as well as the average of the suprahyoid peaks. It was possible to demonstrate that the peak of suprahyoid muscle activity was significantly higher than the peak of infra hyoid muscle activity for swallowing 90 ml of water. Conclusion: The acoustic swallowing parameters in healthy individuals are correlated with the electrical activity of muscles involved in the pharyngeal phase of swallowing.

Objetivo: Correlacionar los datos acústicos de la auscultación cervical con la actividad eléctrica de los músculos involucrados en la fase faríngea de la deglución. Métodos: Se trata de un estudio observacional, transversal, de abordaje cuantitativo y aprobado en enero por CEP/UFSCPA (número 1.389.050). Todos los participantes del estudio firmaron un formulario de consentimiento informado. La fase faríngea de la deglución se evaluó mediante auscultación y electromiografía de superficie. Los individuos ingirieron 90 ml de agua. Los datos de auscultación fueron cargados em el software DeglutiSom®, la duración y la amplitud de la actividad electromiográfica se midió durante la deglución utilizando un dispositivo de electromiografía de superficie Miotec®. El nivel de significancia adoptado fue del 5%. Resultados: Cincuenta y siete mujeres participaron en este estudio. La edad promedio fue 23,4 años. Cabe destacar que a mayor frecuencia de pico promedio de auscultación, menor fue el pico promedio del músculo suprahioideo y a mayor intensidad, mayor fue el pico, así como el promedio de los picos suprahioideos. Fue posible demostrar que el pico de actividad del músculo suprahioideo era significativamente más alto que el pico de actividad del músculo infrahioideo para tragar 90 ml de agua. Conclusión: Los parámetros de deglución acústica en individuos sanos se correlacionan con la actividad eléctrica de los músculos involucrados en la fase faríngea de la deglución.

mRNA expression of myosin heavy chain isoforms in the sphenomandibularis portion of the temporalis muscle / Expresión de ARNm de las isoformas de la cadena pesada de la miosina en la porción esfenomandibular del músculo temporal

SUMMARY: The main objective of this study was to analyze by real-time quantitative polymerase chain reaction (RT-qPCR) the expression patterns of the myosin heavy chain (MHC) isoforms (MHC-I, MHC-IIa, MHC-IIx) in the sphenomandibularis portion of the temporalis muscle. We expected to find differences between the sphenomandibularis and the other portions of the temporalis that could be related to the functional characteristics of the sphenomandibularis identified by electromyography. We dissected the right temporalis muscle of ten adult human individuals (five men and five women). Samples of the anterior and posterior temporalis and of the sphenomandibularis portion were obtained from each dissected muscle. These samples were analyzed by RT-qPCR to determine the percentages of expression of the MHC-I, MHC-IIa and MHC-IIx isoforms. No significant differences were identified between the anterior and the posterior temporalis in the expression patterns of the MHC-I, MHC-IIa and MHC-IIx isoforms. However, there were significant differences between the sphenomandibularis and the anterior temporalis. Specifically, the sphenomandibularis portion had a higher percentage of expression of the MHC-I isoform (P=0.04) and a lower percentage of expression of the MHC-IIx isoform (P=0.003). The pattern of expression that we observed in the sphenomandibularis reflects a greater resistance to fatigue, a lower contraction speed, and a lower capacity of force generation in the sphenomandibularis compared to the anterior temporalis. These characteristics are consistent with electromyographic findings on the functional differences between these two portions.

RESUMEN: El principal objetivo de este estudio fue analizar mediante real-time quantitative polymerase chain reaction (RT-qPCR) los patrones de expresión de las isoformas de la cadena pesada de la miosina (MHC-I, MHC-IIa y MHC-IIx) en la porción esfenomandibular del músculo temporal. Se esperó encontrar diferencias entre el esfenomandibular y las otras porciones del músculo temporal que se pudieran relacionar con las características funcionales del esfenomandibular, identificadas mediante electromiografía. Para obtener estos resultados, se diseccionó el músculo temporal derecho en diez humanos adultos (cinco hombres y cinco mujeres) y se obtuvieron muestras de la porción anterior y posterior del músculo temporal y de su porción esfenomandibular. Estas muestras fueron analizadas mediante RT-qPCR para determinar los porcentajes de expresión de las isoformas MHC-I, MHC- IIa y MHC-IIx. No se identificaron diferencias significativas de los patrones de expresión entre la porción anterior y la porción posterior del músculo temporal, pero sí que se observaron diferencias significativas entre la porción anterior del músculo temporal y su porción esfenomandibular. Concretamente, la porción esfenomandibular presentó un mayor porcentaje de expresión de la isoforma MHC-I (P=0.04) y un menor porcentaje de expresión de la isoforma MHC-IIx (P=0.003). El patrón de expresión que hemos observado en la porción esfenomandibular del músculo temporal refleja una mayor resistencia a la fatiga, una velocidad de contracción más lenta y una menor capacidad de generar fuerza si se compara esta porción con la porción anterior del músclo temporal. Estas características son consistentes con las diferencias funcionales que presentan estas dos porciones, que han sido descritas mediante electromiografía.