Determination of masseter and temporal muscle thickness by ultrasound and muscle hardness by shear wave elastography in healthy adults as reference values.

OBJECTIVES: The purpose of this study is to prospectively investigate the reference values of masseter and temporal muscle thicknesses by ultrasonography and muscle hardness values by shear wave elastography in healthy adults. METHODS: The sample of the study consisted of a total of 160 healthy individuals aged between 18 and 59, including 80 women and 80 men. By examining the right and left sides of each participant, thickness and hardness values were obtained for 320 masseter muscles and 320 temporal muscles in total. RESULTS: The mean masseter muscle thickness was found to be 1.09 cm at rest and 1.40 cm in contraction. The mean temporal muscle thickness was found to be 0.88 cm at rest and 0.98 cm in contraction. The thickness values of the masseter and temporal muscles were significantly greater in the male participants than in the female participants (P < .001). While there were significant differences between the right and left masseter muscle thickness values at rest and in contraction, the values of the temporal muscles did not show a significant difference between the sides. While the resting hardness (rSWE) of the masseter muscle was transversally 6.91 kPa and longitudinally 8.49 kPa, these values in contraction (cSWE) were found, respectively, 31.40 and 35.65 kPa. The median temporal muscle hardness values were 8.84 kPa at rest and 20.43 kPa in contraction. Masseter and temporal muscle hardness values at rest and in contraction were significantly higher among the male participants compared to the female participants (P < .001). CONCLUSION: In this study, reference values for the thickness and hardness of the masseter and temporal muscles are reported. Knowing these values will make it easier to assess pain in the masseter and temporal muscles and determine the diagnosis and prognosis of masticatory muscle pathologies by allowing the morphological and functional assessments of these muscles, and it will identify ranges for reference parameters.

Automated temporalis muscle quantification and growth charts for children through adulthood.

Lean muscle mass (LMM) is an important aspect of human health. Temporalis muscle thickness is a promising LMM marker but has had limited utility due to its unknown normal growth trajectory and reference ranges and lack of standardized measurement. Here, we develop an automated deep learning pipeline to accurately measure temporalis muscle thickness (iTMT) from routine brain magnetic resonance imaging (MRI). We apply iTMT to 23,876 MRIs of healthy subjects, ages 4 through 35, and generate sex-specific iTMT normal growth charts with percentiles. We find that iTMT was associated with specific physiologic traits, including caloric intake, physical activity, sex hormone levels, and presence of malignancy. We validate iTMT across multiple demographic groups and in children with brain tumors and demonstrate feasibility for individualized longitudinal monitoring. The iTMT pipeline provides unprecedented insights into temporalis muscle growth during human development and enables the use of LMM tracking to inform clinical decision-making.

Subfascial dissection and extended temporal muscle detachment for middle fossa approach.

BACKGROUND: The soft tissue dissection for the middle fossa approach requires adequate management of the neuro, vascular, and muscular structures in order to maximize exposure and diminish morbidities. METHODS: An incision anterior to the tragus is performed, extending from the zygomatic process to the superior temporal line. The superior temporal artery is exposed, followed by a subfascial dissection of the frontalis nerve. The temporal muscle is dissected and released from the zygoma. All cranial landmarks are exposed for the 5 × 5 cm temporal fossa craniotomy. CONCLUSION: This novel approach provides a safe and adequate access to perform an extended middle fossa craniotomy.

[Accuracy evaluation of recording maxillomandibular relation with the mandibular kinesiography].

PURPOSE: To evaluate the accuracy of recording maxillomandibular position relationship with the mandibular kinesiography by surface electromyography analysis of the masticatory muscles and MRI of temporomandibular joint (TMJ). METHODS: Eight edentulous patients were selected randomly, and the maxillomandibular position relationship was determined by mandibular kinesiography and traditional method respectively. Then the corresponding bite plates were made to wear. Surface electromyography test of left and right anterior temporal and masseter muscle and magnetic resonance scan of the temporomandibular joint were performed on closed mouth position to record peak potentials, calculate asymmetric indexes, analyze the position relationship between the joint disc and the condyle, measure TMJ joint space. SPSS 18.0 software package was used for data analysis. RESULTS: There was no significant difference in the amplitude of the anterior temporal or masseter muscle, the asymmetry index of total, asymmetry index of masseter, asymmetry index of temporalis, the anterior, upper and posterior spaces of TMJ between the mandibular kinesiography group and the traditional group (P＞0.05). The temporomandibular articular disc process relationship of the two groups were conformed to the normal physiological position relationship. CONCLUSIONS: Mandibular kinesiography could accurately record the maxillomandibular position relationship in patients with edentulous jaws.

Immediate Effect of Ultrasound on Bilateral Masseter Myalgia: A Randomized Dose-Response Clinical Trial.

AIMS: (1) To determine the dose-response relationship of therapeutic ultrasound for TMD-related pain in the masseter muscle among four doses comprised of two intensities (0.4 W/cm2 and 0.8 W/cm2) and two duty cycles (50% and 100%); and (2) to determine if therapeutic ultrasound applied to the masseter muscle would elicit a segmental effect on the ipsilateral temporalis muscle. METHODS: A total of 28 adult women with bilateral myalgia were randomly allocated to one of the four intervention doses. Therapeutic ultrasound was applied on each side of the masseter sequentially for 5 minutes. The following outcomes were measured before and immediately after each intervention: self-reported pain score, pressure pain thresholds for the masseter and temporalis muscles, and intraoral temperature adjacent to the treated masseter. RESULTS: Self-reported pain scores showed neither significant main effects nor significant interaction among the intensity or duty cycle doses (all P > .05). The change in the pressure pain threshold of the masseter showed a significant interaction (P = .02) attributed to the 0.4 W/cm2 and 100% duty cycle dose. Intraoral temperature was significantly increased and associated with the duty cycle (P = .01). A significant segmental effect of the pressure pain threshold of the temporalis was found for intensity (P = .01). CONCLUSION: There was an increase in the pressure pain threshold of the painful masticatory muscles and an increase in intraoral temperature adjacent to the treated area immediately after the use of ultrasound at 0.4 W/cm2 with a 100% duty cycle.

Temporal Muscle and Stroke-A Narrative Review on Current Meaning and Clinical Applications of Temporal Muscle Thickness, Area, and Volume.

BACKGROUND: Evaluating muscle mass and function among stroke patients is important. However, evaluating muscle volume and function is not easy due to the disturbances of consciousness and paresis. Temporal muscle thickness (TMT) has been introduced as a novel surrogate marker for muscle mass, function, and nutritional status. We herein performed a narrative literature review on temporal muscle and stroke to understand the current meaning of TMT in clinical stroke practice. METHODS: The search was performed in PubMed, last updated in October 2021. Reports on temporal muscle morphomics and stroke-related diseases or clinical entities were collected. RESULTS: Four studies reported on TMT and subarachnoid hemorrhage, two studies on intracerebral hemorrhage, two studies on ischemic stroke, two studies on standard TMT values, and two studies on nutritional status. TMT was reported as a prognostic factor for several diseases, a surrogate marker for skeletal muscle mass, and an indicator of nutritional status. Computed tomography, magnetic resonance imaging, and ultrasonography were used to measure TMT. CONCLUSIONS: TMT is gradually being used as a prognostic factor for stroke or a surrogate marker for skeletal muscle mass and nutritional status. The establishment of standard methods to measure TMT and large prospective studies to further investigate the relationship between TMT and diseases are needed.

Intramuscular lipoma of the temporalis muscle extending to the infratemporal fossa: surgical pitfalls and short literature review.

Lipomas are benign tumours of mesenchymal origin, representing one of the most common tumours of the body. They are often observed between the fourth and the sixth decade of life and in 13% of the cases they occur in the head and neck region. In case of symptoms, surgical removal is the treatment of choice; when the formation involves the temporal region, the surgical approach is often challenging due to the presence of the neurovascular structures, such as the temporalis branch of the facial nerve and their potential extension to the nearby structures under the zygomatic arch to either the infratemporal fossa or the buccal region. Recurrence can occur frequently only if there is incomplete removal of lipoma. In this paper, the authors discuss surgical pitfalls of a very rare case of a large-sized symptomatic lipoma extended to the infratemporal and pterygomaxillary fossa, surgically removed via trans-zygomatic hemicoronal approach.

Bite Force, Thickness, and Thermographic Patterns of Masticatory Muscles Post-Hemorrhagic Stroke.

OBJECTIVE: Stroke is a neurological deficit of cerebrovascular origin, considered a 21st-century epidemic that causes functional changes in the human body. This study aimed to evaluate the stomatognathic system of patients after hemorrhagic stroke through the bite force, thickness, and skin temperature in the region of the masseter and temporalis muscles. MATERIAL AND METHODS: Twenty-four subjects were divided into groups: post-hemorrhagic stroke; with right side of the affected body (n = 12) and without the neurological disorder (n = 12). Maximum molar bite force was verified using a digital dynamometer. Muscle thickness was measured using ultrasound images obtained at rest and during maximal voluntary contraction of the masseter and temporalis muscles. Thermographic camera was used to record the thermographic patterns of the masseter and temporalis muscles. Data were subjected to Student's t-test (P < .05). RESULTS: The maximum molar bite force showed significant differences in the right (P = .04) and left (P = .03) sides, with a reduction in force in the post-hemorrhagic stroke group on the affected and unaffected sides. There was a significant difference (P < .05) in the thickness of the left temporal muscle at mandibular rest (P = .01) between groups. The post-hemorrhagic stroke group clinically presented greater muscle thickness in almost 100% of the muscles evaluated in both clinical conditions. There were no significant differences in skin temperature in the masseter and temporal muscles between the groups. CONCLUSIONS: Our results suggest functional changes in the stomatognathic system of subjects after a hemorrhagic stroke, especially concerning molar bite force and masticatory muscle thickness in the temporal muscle (unaffected side).

Does Systemic Arterial Hypertension Change the Function of the Stomatognathic System?

The aim of this study was to evaluate the stomatognathic system of individuals with controlled systemic hypertension through comparison with a disease-free control group. Seventy individuals (44 female and 26 male) were divided into two groups: a controlled systemic hypertension (n=35) and a disease-free control (n=35). The individuals were evaluated on the basis of masticatory cycle efficiency of the value of the ensemble-averaged integrated linear envelope to the electromyographic signal of the masseter and temporalis muscles in the habitual (peanuts and raisins) and non-habitual chewing (Parafilm M); molar bite force (right and left) and ultrasound images from the bilateral masseter and temporal muscles at rest and maximum voluntary contraction. The data obtained were tabulated and submitted to statistical analysis (p<0.05). There was a significant difference between groups in the habitual (peanuts and raisins) and non-habitual (Parafilm M) chewing with reduced muscle activity to controlled systemic hypertension group. Muscle thickness occurred significant difference between groups at rest and maximum voluntary contraction of the temporalis muscles. There was no significant difference between groups in maximum molar bite force. The present study findings indicate that the controlled systemic hypertension promotes functional changes of the masticatory system, especially with respect to its masticatory efficiency and muscle thickness.

Temporalis muscle thickness as an indicator of sarcopenia predicts progression-free survival in head and neck squamous cell carcinoma.

Temporalis muscle thickness (TMT) on brain magnetic resonance imaging (MRI) is correlated with sarcopenia and can be a predictive marker for survival in patients with brain tumors, but the association of TMT on head and neck computed tomography (CT) with survival in head and neck squamous cell carcinoma (HNSCC) remains unclear. We investigated whether TMT on CT could predict progression-free survival (PFS) in patients with HNSCC. A total of 106 patients with newly diagnosed HNSCC were included in this retrospective study. The patients underwent baseline head and neck CT and/or MRI between July, 2008 and August, 2018. The correlation between TMT on CT and MRI was tested using intraclass correlation coefficient (ICC). The cut-off value of TMT on CT for determining tumor progression was identified using receiver-operating characteristic curve analysis. Uni- and consecutive multi-variable Cox regression models were used to verify the association between TMT and PFS. TMT on CT and MRI showed excellent correlation (ICC, 0.894). After a mean follow-up of 37 months, 49 out of 106 patients showed locoregional recurrence and/or distant metastasis. The cut-off TMT of 6.47 mm showed good performance in predicting tumor progression (area under the curve, 0.779). The Cox regression model showed that TMT ≤ 6.24 mm (median value in study population) was a significant contributing factor for predicting shorter PFS (hazard ratio 0.399; 95% confidence interval 0.209-0.763; P = .005). TMT may be used as a surrogate parameter for pre-treatment sarcopenia and could help predict PFS in patients with HNSCC.

Paradoxical Temporal Enlargement: An Expansion of Superficial Temporal Fat Pad Following Interfacial Technique for Pterional Craniotomy.

OBJECTIVE: Contour irregularities in the temporal region have been reported previously after procedures involving temporal dissection. In this study, we report paradoxical temporal enlargement (PTE) following interfascial pterional craniotomy. METHODS: A retrospective review of patients who underwent a unilateral transcranial procedure with frontotemporal approach at our institution between September 2013 and December 2017 was performed. Patients with a previous craniotomy or bilateral craniotomy were excluded. Radiological imaging series including computed tomography and magnetic resonance imaging were utilized to calculate temporal soft tissue volumes both preoperatively and postoperatively by using advanced software technology. Relative soft tissue volume differences between the operative side and the contralateral side were calculated at different time-points including preoperative, 3-months follow-up (3M), 12-months (12M) follow-up, and the last follow-up (LFU, over 1-year). RESULTS: Forty-three patients were included. Mean age was 52.7 ± 4.5 years. Mean follow-up was 27.9 ± 15.8 months. Significant changes of temporal fat pad relative-volume difference were observed between the preoperative and the corresponding 3M (t [82] = -2.8865, P = 0.0050); 12M (t [77] = -4.4321, P < 0.0001), and LFU (t [74] = -4.9862, P < 0.0001) postoperative time points. No significant change of the temporalis muscle was observed between the preoperative and the corresponding 3M (P = 0.3629), 12M (P = 0.1553), or LFU (P = 0.0715). Soft tissue volume showed a significant increase on the operative side between the preoperative and the corresponding LFU (t [74] = -2.5866, P =  0.0117). CONCLUSIONS: Paradoxical temporal enlargement with more than 10% volumetric change was observed in 24% of the patients at their LFU (>1-year). This change was not due to temporalis muscle changes. Paradoxical temporal enlargement was due to hypertrophy of the superficial temporal fat pad. Before surgical correction of postoperative temporal contour changes, it is important to obtain imaging and characterize the etiology of the deformity.

A novel radiographic marker of sarcopenia with prognostic value in glioblastoma.

OBJECTIVE: Sarcopenia is an important prognostic consideration in surgical oncology that has received relatively little attention in brain tumor patients. Temporal muscle thickness (TMT) has recently been proposed as a novel radiographic marker of sarcopenia that can be efficiently obtained within existing workflows. We investigated the prognostic value of TMT in primary and progressive glioblastoma. METHODS: TMT measurements were performed on magnetic resonance images of 384 patients undergoing 541 surgeries for glioblastoma. Relationships between TMT and clinical characteristics were examined on bivariate analysis. Optimal TMT cutpoints were established using maximally selected rank statistics. Predictive value of TMT upon postoperative survival (PS) was assessed using Cox proportional hazards regression adjusted for age, sex, Karnofsky performance status (KPS), Stupp protocol completion, extent of resection, and tumor molecular markers. RESULTS: Average TMT for the primary and progressive glioblastoma cohorts was 9.55 mm and 9.40 mm, respectively. TMT was associated with age (r = -0.14, p = 0.0008), BMI (r = 0.29, p < 0.0001), albumin (r = 0.11, p = 0.0239), and KPS (r = 0.11, p = 0.0101). Optimal TMT cutpoints for the primary and progressive cohorts were ≤ 7.15 mm and ≤ 7.10 mm, respectively. High TMT was associated with increased Stupp protocol completion (p = 0.001). On Cox proportional hazards regression, high TMT predicted increased PS in progressive [HR 0.47 (95% confidence interval (CI)) 0.25-0.90), p = 0.023] but not primary [HR 0.99 (95% CI 0.64-1.51), p = 0.949] glioblastoma. CONCLUSIONS: TMT correlates with important prognostic variables in glioblastoma and predicts PS in patients with progressive, but not primary, disease. TMT may represent a pragmatic neurosurgical biomarker in glioblastoma that could inform treatment planning and perioperative optimization.

Sex Differences in the Temporalis Tendon-Aponeurotic Complex: An in vivo MRI Macroscopic Analysis in Children and Adolescents.

The tendon-aponeurosis complex (TAC) of the temporalis dissipates forces produced during function. Abnormally reduced temporalis TACs have been found in individuals with chronic muscular temporomandibular disorders - a painful musculoskeletal condition that is more frequent in women than men. Whether there are sex differences in the temporalis TAC in healthy individuals is currently unknown. Here, we characterized and measured the temporalis TAC in healthy male and female young individuals between 5 and 15 years old to determine whether the volume of the temporalis TAC and the TAC-to-muscle ratio are different between males and females. We collected MRI studies from 90 healthy individuals, including equal numbers (15 M and 15 F) of young children (ages 5-7), children (9-11), and adolescents (13-15) and segmented the right temporalis and its TAC using software. Using general linear models, we tested the effect of sex, age, and their interaction on the volumes of the temporalis and its TAC, and the TAC-to-muscle ratio. The volumes of the temporalis and its TAC increased with age (both p < 0.001) and were not affected by sex (p = 0.252 and p = 0.179) or by the interaction sex-by-age (p = 0.079 and p = 0.095, respectively). The TAC-to-muscle ratio did not change significantly with age (p = 0.655) and was not affected by sex (0.438) or by the interaction sex-by-age (0.524). We provide, for the first time, volumetric data of the temporalis TAC in children and adolescents. The volumes of the temporalis TAC and the TAC-to-muscle ratio are not different between male and female individuals until the age of 15.

Preoperative and postoperative assessment of temporal and masseter muscle size with magnetic resonance imaging in patients undergoing unilateral temporomandibular joint surgery.

The aim of this study was to assess any change between the preoperative and postoperative sizes of temporal and masseter muscles with magnetic resonance imaging (MRI) in patients undergoing unilateral temporomandibular joint surgery. This study was designed and implemented retrospectively. For clinical evaluation, a visual analog scale (VAS) and maximum mouth opening (MMO) were used. In order to make a preoperative diagnosis and perform a 6-month control, muscle size was measured in millimeters (mm) on T1 axial sections in MRI. Statistical analyses were performed using the SPSS 23.0 software package. Numeric variables were compared between two dependent groups using the Wilcoxon signed rank test. Statistical significance was set at p < 0.05. Twelve patients who underwent unilateral discectomy plus dermis-fat grafting, with classical preauricular inverse L incision, were included in the study, and data for eleven female patients were evaluated. The difference in size between the operated and non-operated sides was found to be statistically insignificant at the preoperative stage for both masseter muscle (operated side mM: 13.264 ± 1.822 mm; non-operated side mM: 13.264 ± 2.315 mm; pM = 0.929) and temporal muscle (operated side mT: 20.345 ± 2.609 mm; non-operated side mT: 20.582 ± 2.366 mm; pT = 0.594). There was a significant size reduction in the masseter muscle on the operated side in the postoperative period (preop mM: 13.264 ± 1.822 mm; postop mM: 12.036 ± 1.728 mm; pM = 0.018). Although there was also a size reduction in the operated side of the temporal muscle in the postoperative period, that difference did not reach statistical significance (preop mT: 20.345 ± 2.609 mm; postop mT: 19.445 ± 1.603 mm; pT = 0.182). On the non-operated side, there were no significant postoperative changes in the sizes of either the masseter muscle (preop mM: 13.264 ± 2.315 mm; postop mM: 12.682 ± 2.059 mm; pM = 0.248) or the temporal muscle (preop mT: 20.582 ± 2.366; postop mT: 19.891 ± 3.487 mm; pT = 0.625). Considering the study findings as a whole, a size reduction was observed in the operated side of the masseter muscle after TMJ surgery. The etiology of this change may be surgical trauma to the temporal and masseter muscles, skeletal alteration resulting from condylar change secondary to discectomy, and patients restraining themselves from application of maximum bite force as a result of a self-protection mechanism due to postoperative pain.

High protein intake after subarachnoid hemorrhage improves oral intake and temporal muscle volume.

BACKGROUND & AIMS: Dysphagia is a common sequela following stroke. Patients with subarachnoid hemorrhage (SAH) often develop atrophy of the temporal muscle, but its clinical significance remains unclear. This study aimed to investigate whether temporal muscle volume (TMV) is related to subsequent oral intake in patients with SAH and evaluate the predictors of temporal muscle atrophy. METHODS: We performed a retrospective analysis of 60 SAH patients receiving enteral nutrition in the acute hospitalization phase at a single center between 2009 and 2019. The TMV was segmented automatically from computed tomography images and measured on admission and at week 2. Patients with a ≥20% TMV reduction were assigned to the atrophy group (n = 24) and those with a <20% TMV reduction were included in the maintenance group (n = 36). The patients' oral intake status was assessed at week 2 using the Food Intake LEVEL Scale (grade of 7-9 considered good ingestion), and the modified Rankin scale (mRS) was used at discharge (grade of 0-2 considered good prognosis). Additional data on age, sex, body mass index, severity of SAH, and protein intake were collected on day 4. RESULTS: The maintenance group had significantly better oral intake and mRS scores compared to the atrophy group. TMV maintenance significantly affected oral intake at week 2 and the mRS score at discharge. Multivariable logistic regression analysis revealed that protein intake on day 4 significantly influenced the maintenance of TMV. CONCLUSIONS: High protein nutrition in the acute stage of SAH contributes to temporal muscle maintenance and improves oral intake.

Reliability and validity of measuring temporal muscle thickness as the evaluation of sarcopenia risk and the relationship with functional outcome in older patients with acute stroke.

BACKGROUND: Pre-stroke sarcopenia associated with poor functional outcomes. However, diagnosis of pre-stroke sarcopenia is often difficult in patients with acute stroke. Thus, we investigated the reliability and validity of measuring temporal muscle thickness (TMT) as an indicator of sarcopenia risk and its relationship with functional outcome in older patients with acute stroke. METHODS: We conducted a cross-sectional and longitudinal study of the patients with acute elderly stroke in a single neurosurgical hospital. We measured TMT manually using brain computed tomography (CT) by two examiners. Sarcopenia risk, malnutrition risk, inflammation, comorbidities, and modified Rankin Scale (mRS) scores at 3 months after stroke were additionally assessed. Inter-rater reliability of TMT was determined by calculating the intra-class correlation coefficient ([ICC] 2,1). Multiple linear regression analyses was used to determine whether sarcopenia risk was independently associated with TMT, and logistic regression was used to evaluate the relationship between TMT and poor functional outcome (mRS > 3). RESULTS: A total 289 acute elderly stroke patients (163 men and 126 women; mean age: 76 years) were enrolled in this study. Regarding the reproducibility of TMT, good reliability was found; ICC2,1 = 0.759 (95 % confidence interval = 0.705-0.804). Multiple linear regression analyses for TMT after adjusting for potential confounders showed that sarcopenia risk was independently associated with TMT in older patients with acute stroke (ß = -0.138, p = 0.02). After adjusting for variables, disease severity and comorbidities were the only independent predictors for poor functional outcome, but not TMT. CONCLUSIONS: TMT measurement using brain CT is a reliable and variable method to evaluate sarcopenia risk, but is not related to functional outcome in older patients with acute stroke.

Association between temporal muscle thickness and clinical outcomes in patients with newly diagnosed glioblastoma.

PURPOSE: Temporal muscle thickness (TMT) has been suggested as a novel biomarker that can represent sarcopenia in head and neck malignancies. This study investigated the association of TMT with clinical outcomes in patients with newly diagnosed glioblastoma (GBM). METHODS: Using electronic medical records, all GBM patients between 2008 and 2018 at Seoul St. Mary's Hospital were reviewed. Total 177 patients met our eligibility criteria. RESULTS: The thinner group who had TMT less than the median showed shorter overall survival (OS) and progression-free survival (PFS) than the thicker group who had TMT more than median (OS; 11.0 versus 18.0 months, p < 0.001, and PFS; 6.0 versus 11.0 months, p < 0.001). In the multivariate analysis, the thinner group had negative associations with OS and PFS (OS; HR 2.63 (1.34-2.63), p < 0.001, and PFS; HR 2.21 (1.34-2.50), p = 0.002). We also performed propensity score matching between the thinner and thicker groups to minimize the potential bias. The thinner group showed shorter OS and PFS (OS; 13.5 versus 19.0 months, p = 0.006, and PFS; 6.5 versus 9.0 months, p = 0.028) and had negative associations with OS and PFS than the thicker group (OS; HR 1.90 (1.19-3.03), p = 0.008, and PFS; HR 1.70 (1.07-2.70), p = 0.026) in matched patients. CONCLUSION: Our findings suggest that TMT can be a useful prognostic biomarker for clinical outcomes in GBM patients. Further preclinical and clinical studies could help elucidate this association of sarcopenia with clinical outcomes in GBM patients.

Observations on the growth of temporalis muscle: A 3D CT imaging study.

This study investigates the hypothesis that there is, during childhood, a disproportionate age-related expansion of the origin of temporalis muscle compared to the growth of the underlying skull. Lateral projections of 50 randomly selected 3D reformatted computerized tomographic (CT) scans (yielding 100 temporalis muscles) of children aged >0.6 to 15 years scanned for conditions that did not affect the shape of their head or face were windowed to provide the optimum delineation of temporalis muscle against the underlying bone. Vertical and anterior-posterior measurements of the muscle made independently by two observers were compared with those of the skull along the same planes. The development of the anterior temporal crest was also assessed. The intraclass correlation coefficient for differences in the measurements made by each observer ranged from good to excellent. The muscle and skull measurements were used to produce a ratio of muscle-to-skull lengths in both vertical and horizontal planes. Analysis of these ratios showed a statistically significant increase in the vertical reach of temporalis with age (Pearson correlation coefficient (R) =0.7826; p < 0.05) compared to the growth of the skull along the planes chosen for the study-but less so for its horizontal reach (R = 0.5073. p < .001). There were no significant differences between right/left or male/female measurements. There was also a substantial level of agreement between both observers in their assessment of the development of the temporal crest. The mean age of children in whom a fully formed temporal crest could be identified (10.6 years) was significantly greater (p < 0.001) than that of the 38 remaining subjects (6.0 years). These results confirm that there is, in response to increased masticatory/dietary demands during childhood, a disproportionate increase in the vertical and (to a lesser extent) horizontal reach of temporalis muscle over its origin from the temporal, frontal, sphenoid, and parietal bones compared the growth of the skull. It is proposed that surgical interference with this normal process is responsible for the soft tissue component of late-developing deformity that can occur following early (at 6-18 months of age) operations for the correction of trigonocephalic head shape associated with metopic synostosis.

Methods of Masseter and Temporal Muscle Thickness and Elasticity Measurements by Ultrasound Imaging: A Literature Review.

BACKGROUND: The positive correlation between changes in the morphology of masseter and temporal muscles and some disorders, inclines diagnosticians to search for an effective method of assessing muscle thickness and elasticity. Ultrasound imaging, as a relatively simple and cheap method, seems to be a useful diagnostic tool. OBJECTIVE: The aim of this study was to present the existing ultrasound imaging methods in the assessment of the elasticity and thickness of the masseter and temporal muscles. METHODS: The literature review has been done with a focus on the accurate description of the masseter and/or temporal muscle examination by ultrasonography imaging methods. Articles were categorized into two groups. The first group included articles in which muscle thickness was assessed by ultrasound imaging. The second group concerned the elasticity aspect of mentioned muscles. RESULTS: It is difficult to achieve an objective protocol of masseter and temporal thickness assessment by ultrasonography and there is no method that has been fully verified in terms of reliability. The shear-wave sonoelastography revealed higher-level reliability of masseter muscle elasticity than strain sonoelastography. During the shear-wave sonoelastography, the effect of scan plane in relation to masseter muscle pennation and the day-to-day variation were statistically significant. With regard to elasticity of temporal muscle, further research is needed. CONCLUSION: This review has shown that there is a limited number of methods for masseter and temporal muscle thickness and elasticity measurements by ultrasonography. All procedures (methods) were not fully verified in terms of reliability and agreement. Thus, it is still necessary to develop standardized procures to assess thickness and elasticity of the masseter and temporal muscles with appropriate reliability and accuracy.

Structural abnormalities in the temporalis musculo-aponeurotic complex in chronic muscular temporomandibular disorders.

Some forms of chronic pain are thought to be driven and maintained by nociceptive input, which can drive plasticity within nociceptive pathways. We have previously identified abnormalities along the entire nociceptive pathway in chronic myalgic temporomandibular disorders (mTMD), including the trigeminal nerves, brainstem pathways, and in the thalamus and somatosensory cortex. These data suggest that there is a peripheral nociceptive drive in mTMD, but the source of this nociceptive activity remains unknown. Here, our aim was to determine whether structural abnormalities exist in the muscles of mastication of patients with chronic mTMD. Specifically, we tested whether the volume of the temporalis muscle and its tendon-aponeurosis complex (TAC, a structure that dissipates forces in a muscle) in mTMD patients differ compared to age- and sex-matched controls. To do so, we segmented these structures on T1-weighted structural magnetic resonance images. We found that muscle volumes in mTMD were not different to controls. However, the mTMD group had significantly smaller volumes of the bilateral temporalis TAC, and thus a smaller TAC-to-muscle volume ratio. These findings were consistent across 2 independent cohorts of 17 mTMD patients, compared to 17 age- and sex-matched controls. We propose a model where reduced TAC-to-muscle ratio could result in a predisposition to muscle tissue injury. In sum, abnormalities of the temporalis muscles in mTMD supports our hypothesis that chronic mTMD pathophysiology may be related to peripheral nociceptive barrage originating from the muscles of mastication.