Masseter Muscle Activity in Orthodontically Treated Patients with a History of Temporomandibular Joint Disorder: An Electromyographic Study

ABSTRACT@#The present study aimed to evaluate the surface electromyography (sEMG) activity of the masseter muscles in patients with a history of temporomandibular joint disorder (TMJD) who received orthodontic treatment. In total, 22 participants aged 18–35 years old were included in this study. They were divided into the control group (patients without a history of TMJD [n = 11]) and the test group (those with a history of TMJD [n = 11]). Each participant underwent sEMG of the right and left masseter muscles at 5-s maximum voluntary contraction (MVC). Results showed that the TMJD group had a lower sEMG activity of masseter muscles at MVC than the non-TMJD group. However, the differences were not statistically significant (p > 0.05, t-test). The Spearman’s correlation coefficient test revealed a weak negative correlation between muscle activity on sEMG and history of TMJD (p > 0.05). In conclusion, orthodontically treated patients in TMJD group have reduced masseter muscle activity during MVC, compare to the non-TMJD group.

Hipertermia severa post cirugía cardiaca: presentación de un caso / Severe hyperthermia present after a heart surgery

Introducción: La hipertermia maligna es una miopatía hereditaria causada por un trastorno del receptor rianodine del retículo sarcoplásmico rugoso del músculo estriado; se manifiesta en pacientes susceptibles por la exposición a agentes halogenados o succinilcolina. Objetivo: Presentar la evolución de una paciente con hiperpirexia severa post cirugía cardiaca. Caso clínico: Paciente de 56 años, anunciada para reemplazo valvular aórtico, ASA III, clase funcional NYHA II-III, sin otros antecedentes. A su llegada a la Unidad de Cuidados Intensivos Postoperatorios se constató gran contractura muscular, generalizada y en particular de los músculos maseteros, incremento progresivo del CO2 arterial (105 mmHg), acidosis metabólica, bajas relaciones paO2/FiO2, orinas de color rojo vino, hiperpotasemia, taquicardia sinusal con contracciones ventriculares prematuras frecuentes, salvas autolimitadas de taquicardia ventricular, bajo gasto cardiaco severo e hiperpirexia mantenida de 41ºC para lo cual se tomaron medidas sintomáticas. Después de 8 horas, disminuyó la fiebre, se restableció el medio interno, el aclaró el color de la orina, la hemodinámica se estabilizó y se constató elevación de la creatinina sérica, que disminuyó progresivamente en los días siguientes. A las 48 horas se destetó de la ventilación mecánica. Se dio el alta de la UCIP al quinto día. Conclusiones: Independientemente, que no se realizaron pruebas específicas para hipertermia maligna, se trata de un caso complejo con una hiperpirexia severa y evolución satisfactoria.

Introduction: Malignant hyperthermia is a hereditary myopathy caused by a rianodine receptor disorder of rugous sarcoplasmic reticulum of the skeletal muscle becomes clear in patients oversensitive to exposition to halogen agents or to succinylcholine. Objective: To present the course of patient presenting with a severe hyperpyrexia after a heart surgery. Clinical case: Patient aged 56 programmed for an aortic valvular replacement, ASA III, functional class NYHA-II-III without other backgrounds. At her arrival to Postperative Intensive Care Unit (POICU) it was noted a significant widespread muscular contracture mainly in masseter muscles, a progressive increase of the arterial CO2 (105 mm Hg), metabolic acidosis, low paO2/FiO2 relations, urine of red wine color, hyperpotassemia, sinus tachycardia with frequent early ventricular contractions, self-limited of ventricular tachycardia, a sever and low cardiac output and sustained hyperpyrexia if 41°C taking measures related to symptoms. At 8 hours fever decreased with restoration of internal environment, urine color cleared, hemodynamics was stable verifying a rise of serum creatinine which decreased progressively after few days. At 48 hours patient was weaned of the mechanical ventilation. At 5 days she was discharged from the POICU. Conclusions: Apart from there were not specific tests to malignant hyperthermia, it is a complex case presenting with a severe hyperpyrexia and a satisfactory course.

Evaluation of normal masseter muscles on ultrasonography / 대한구강악안면방사선학회지

PURPOSE: To assess the internal echo intensity and morphological variability of masseter muscles on ultrasonography and to establish diagnostic criterion of estimation. MATERIALS AND METHODS: Participants consisted of 50 young adults (male 25, female 25) without pathologic conditions and with full natural dentitions. Sonographic examinations were done with real time ultrasound equipment as Logiq 500 (GE Medical Systems, Seoul, Korea) at 3 parts according to lines paralleling with ala-tragus line as reference line. The thickness and area of masseter muscles according to reference line in cross-sectional images were measured at rest and at maximum contraction. The visibility and width of the internal echogenic intensity of the masseter muscles were also assessed and the muscle appearance was classified into 4 types. Data were statistically analyzed by paired t-test and chi-square-test. RESULTS: 1. When comparing the thickness and area of masseter muscles concerning with gender, there was few significant difference between right and left sides, however, there were significant differences between males and females except for the greatest thickness of left side. 2. The changes of the greatest thickness and the area between rest and maximum contraction showed that the part of the least thickness manifested more increase at maximum contraction. 3. Each part the manifestations of the internal echogenic intensity of the masseter muscles were different depending on the locations. But there was no statistically significance. CONCLUSION: Changes of muscles thickness with contraction and internal echogenic intensity with locations showed great disparity within the masseter muscles, which will be diagnostic criteria for pathophysiologic and anatomic changes of masseter muscles.

Relationship between lower facial morphology and the size of masseter and medial pterygoid by CT scanning / 中华医学美学美容杂志

Objective To determine the mechanism underlying the mandibular angle enlargement and to provide a morphological basis for correcting the enlarged mandibular angle. Methods By axial computed tomography, it is possible to measure the width and length of the masseter and the medial pterygoid, the gonial angle, and the vertical height of the posterior mandible. The date were initially analysed by using a simple correctionials and indpendent sample T test. Results The distance between two Go points and gonial angle were significantly related with the thickness of masseter muscle, but the thickness of the medial pterygoid was on the contrary. There was significant differences between the group of prominence and the normal control in the gonial angle, the distance between two Go points and thickness of masseter . But there was no difference between the the two groups in the thickness of medial pterygoid. Conclusion The thickness of the masseter muscle is an important factor that affects the lower facial morphology. The hypertrophy of masserter muscle may cause the mandibular angle enlargement.