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Purpose: The potential relationship between mastication ability and cognitive function in idiopathic normal pressure hydrocephalus (iNPH) patients is unclear. This report investigated the association between mastication and cognitive function in iNPH patients using the gray level of the co-occurrence matrix on the lateral pterygoid muscle., Methods: We analyzed data from 96 unoperated iNPH patients who underwent magnetic resonance imaging (MRI) between December 2016 and February 2023. Radiomic features were extracted from T2 MRI scans of the lateral pterygoid muscle, and muscle texture parameters were correlated with the iNPH grading scale. Subgroup analysis compared the texture parameters of patients with normal cognitive function with those of patients with cognitive impairment., Results: The mini-mental state examination score correlated positively with the angular second moment (P < 0.05) and negatively with entropy (P < 0.05). The dementia scale (Eide's classification) correlated negatively with gray values (P < 0.05). Gray values were higher in the cognitive impairment group (64.7 ± 16.6) when compared with the non-cognitive impairment group (57.4 ± 13.3) (P = 0.005). Entropy was higher in the cognitive impairment group (8.2 ± 0.3) than in the non-cognitive impairment group (8.0 ± 0.3) (P < 0.001). The area under the receiver operating characteristic curve was 0.681 (P = 0.003) and 0.701 (P < 0.001) for gray value and entropy, respectively., Conclusion: Our findings suggest an association between heterogeneity of mastication and impaired cognitive function in iNPH patients and highlight muscle texture analysis as a potential tool for predicting cognitive impairment in these patients., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Background: In human anatomy, there are well-known the foramina of the greater sphenoidal wing, the foramen rotundum, the foramen ovale, the foramen spinosum, as well as the inconstant sphenoidal emissary foramen of Vesalius and the foramen of Arnold. Different canals are found in several species of rodents, such as the alisphenoid and sphenopterygoid (SPC) canals., Method: It was re-explored an archived computed tomography angiogram of a 60 y.o. female case., Results: Bilateral superior recesses of the pterygoid fossae (SRPF) and a right SPC were found. The SRPF on each side penetrated the non-lamellar pterygoid root and superiorly reached the sphenoidal sinus wall. Upper fibres of medial pterygoid muscles were inserted into each SRPF. An unexpected SPC was found on the right side. It opened superiorly on the lateral side of the foramen rotundum and inferiorly at a pterygoid foramen in the superior end of the posterior margin of the lateral pterygoid plate. A sphenoidal emissary vein traversed that SPC to drain into the pterygoid plexus., Conclusion: The SRPF and SPC could also be found in humans. As the sphenoidal emissary veins are surgically relevant, they should not be further regarded as exclusively crossing the foramen of Vesalius but also the SPC., (© 2024. The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.)

The maxillary artery (MA) leaves from the external carotid artery and further courses through the infratemporal fossa to reach the pterygopalatine fossa. It typically has an ascending course either on the lateral or on the medial side of the inferior bundle of the lateral pterygoid muscle. While studying retrospectively, the computed tomography angiogram of an adult male case with peculiar tortuosities of the MA was documented. The left MA described a large inferior sagittal loop applied on the mandible's ramus's inner cortical in the pterygomandibular space's upper part. That loop reached 1.66 cm inferior to the mandible's notch and 0.5 cm superior to the mandibular foramen and was applied on the mandible's lingula (spine of Spix). That MA continued to the pterygomaxillary suture, and a second superior coronal loop was found applied on the posterior wall of the maxillary sinus, reaching the inferior orbital fissure. It is therefore mandatory to take good care in the decortication of the mandibular ramus or during osteotomies of the ramus. When an inferior loop of the MA approaches the spine of Spix, bleeding when an inferior alveolar nerve block is performed seems hardly avoidable., Competing Interests: The authors have no conflict of interest to declare., (Copyright © 2024 by Mutaz B. Habal, MD.)

Fibers of the lateral pterygoid muscle (LPM) occasionally originate on the posterior surface of the maxilla. Anatomic exploration of an adult patient's cone beam computed tomography files revealed a previously unreported unilateral anatomic variant of the LPM. The variant consisted of a distinctive muscular slip that originated on the tuberosity of the maxilla and coursed postero-laterally through the notch of the mandible to insert on an accessory pterygoid fovea on the outer condylar pole. This maxillomandibular muscle was lateral to the inferior head of the LPM. Therefore, it could contribute to the antero-inferior displacement and medial rotation of the mandibular condyle during the movements of the temporomandibular joint. The maxillomandibular muscle should be added to the extensive spectrum of anatomical variations of the LPM; however, prevalence studies should assess whether its maxillary attachment is the rule or the exception., Competing Interests: The authors report no conflicts of interest., (Copyright © 2023 by Mutaz B. Habal, MD.)

Background: The article presents a rare case of acute malocclusion produced by a unilateral partial tear of the lateral pterygoid muscle and an up-to-date literature review of the pathology., Clinical Presentation: A 37-year-old female was examined; her chief complaints were pain on the right side of the temporomandibular joint (TMJ) area and mastication impairment associated with major occlusal modifications and anterior open bite. After magnetic resonance imaging (MRI) and cone beam computed tomography (CBCT) of the TMJ and subsequent MRI for soft tissue, the final diagnosis was a partial right lateral pterygoid muscle tear., Conclusion: The case shows the value of combined imaging in temporomandibular disorders (TMD) and the importance of soft tissue evaluation in addition to articular examination, as the primary pathology might lie outside the joint. The authors' review of the current literature did not hitherto reveal a similar case.

Objective: To use quantitative MRI to assess gender differences in lateral pterygoid muscle (LPM) characteristics in patients with anterior disk displacement (ADD)., Methods: Lateral pterygoid muscle of 51 patients diagnosed with temporomandibular joint disorders (TMD) who underwent T1-weighted Dixon and T1-mapping sequences were retrospectively analyzed. There were 34 female patients (10 with bilateral normal position disk [NP]; 24 with bilateral ADD) and 17 male patients (eight with bilateral NP; nine with bilateral ADD) among them. After controlling for age, differences in fat fraction, T1 value, volume and histogram features related to gender and disk status were tested with 2-way ANCOVA or Quade ANCOVA with Bonferroni correction., Results: Volume of LPM in NP was significantly smaller than that of ADD (p < 0.001). Fat fraction of LPM in females with NP was significantly higher than males with NP (p < 0.05). Females with ADD showed a significantly higher T1 value (p < 0.05), and higher intramuscular heterogeneity than males with ADD., Conclusions: Lateral pterygoid muscle in female TMD patients presented more fatty infiltration in the NP stage and might present more fibrosis in the ADD stage compared with males. Together, this leads to more serious intramuscular heterogeneity during the pathogenesis of ADD in females., (© 2022 Wiley Periodicals LLC.)

Objective: We aimed to evaluate the effectiveness of clinical examination combined with texture analysis of magnetic resonance imaging (MRI) and fasciculation patterns of the lateral pterygoid muscle (LPM) in distinguishing among the different anatomic causes of temporomandibular disorder., Methods: We divided the patients into four groups: healthy control (HC), disk without displacement (DWoD), disk displacement with reduction (DDWR), and disk displacement without reduction (DDWoR). Demographic information and clinical symptoms of patients in each group were recorded. LPM textures were compared among groups. LPM fasciculation was examined. P<0.05 indicated significant difference., Results: Several clinical symptoms and signs, but not age or sex, differed significantly among groups. Oblique sagittal planar MRI revealed significant differences in the parameters of Angular Second Moment, Contrast, Correlation, Inverse Difference Moment, and Entropy between the healthy controls and the 3 patient groups. MRI of the patients, both without and with disk displacement, demonstrated relative uniformity in gray distribution and correlation of gray values, with greater complexity but an unclear texture and no obvious regularity. The proportion of type B LPM fascicles was significantly higher in the DDWR and DDWoR groups CONCLUSION: Temporomandibular disorder, without and with disk displacement, is associated with clinical symptoms and texture analysis values that differ from healthy muscle. The types of LPM fascicles are related to the position of the articular disk., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objective: To explore the correlation between the attachment type of lateral pterygoid muscle (LPM) and the position of temporomandibular joint (TMJ) disc in patients with temporomandibular disorders (TMD) by using wireless amplified magnetic resonance imaging detector (WAND) coupled with conventional head and neck joint coil for high resolution imaging of TMJ. Methods: Eighty-five patients with TMD diagnosed by oral and maxillofacial surgeons of Guizhou Provincial People's Hospital from October 2019 to January 2022 were collected. A total of 160 TMJ were included. There were 16 males and 69 females, aged (32.7±14.2) years. All patients were scanned with open, closed oblique sagittal and coronal WAND coupled head and neck coils with bilateral TMJ. Based on TMJ and LPM high resolution imaging, to explore the correlation between LPM attachment types and the position of TMJ disc in TMD patients, and to evaluate the potential clinical value of LPM attachment types in TMD patients. χ 2 test and Pearson correlation analysis were used to evaluate the correlation between LPM attachment type and TMJ disc location. Results: There were three types of LPM attachment: type Ⅰ in 51 cases [31.9% (51/160)], type Ⅱ in 77 cases [48.1% (77/160)] and type Ⅲ in 32 cases [20.0% (32/160)]. There was a significant correlation between the type of LPM attachment and the position of articular disc ( χ 2 =28.20, P =0.002, r =0.776). There was no statistical significance between the type of LPM attachment and the reversible displacement of articular disc ( χ 2 =0.24, P =0.887, r =0.825). Conclusions: There is a correlation between the attachment type of LPM and the position of the disc in TMD patients. WNAD coupled with conventional head and neck joint coil TMJ high resolution scan can provide reliable imaging evidence for TMD patients in evaluating the type of LPM attachment and the location of disc.

Botulinum toxin type A (BTX-A) injection using nerve stimulation or electromyography for recurrent temporomandibular joint (TMJ) dislocation has been reported for several years. However, using the available equipment like a nerve stimulator or an electromyograph is uncommon, and ultrasound guidance is convenient and requires no additional resources. In this report, we used ultrasound as a tool to achieve BTX-A injections in a patient with a traumatic brain injury to treat her TMJ dislocation. One week after the injections, she had no more dislocation. She remained symptom free during the 3 months of follow-up, and her clinical symptoms improved without significant complications. This is the first report using ultrasound guidance for BTX-A injections to treat recurrent TMJ dislocation. This treatment is an effective and safe technique that could be performed timely and locally without referral to a center with electromyography facilities., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objectives: Magnetic resonance imaging (MRI) is useful for assessing temporomandibular disorders (TMDs). However, few studies have attempted texture analysis of the lateral pterygoid muscle in patients with rheumatoid arthritis (RA). This study aims to investigate the usefulness of MRI texture analysis of the lateral pterygoid muscle of patients with RA of the temporomandibular joint (TMJ)., Methods: We analyzed the data from 36 patients (18 non-RA patients and 18 RA patients) who complained of pain and underwent MRI between April 2008 and August 2021. From the MRI scans of these patients, 279 radiomics features were extracted using STIR image data of the ROIs on the lateral pterygoid muscle of patients with RA and analyzed using MaZda ver. 3.3. Seven gray-level co-occurrence matrix features (Sum entropy, Sum variance) were picked up using the Fisher coefficient, for comparison between the RA and non-RA groups. Data analysis was performed using the Mann-Whitney U test A P value of < 0.05 was considered as statistically significant., Results: All seven lateral pterygoid muscle radiomic features indicated significant differences between the non-RA and RA groups (P < 0.05)., Conclusion: MRI texture analysis shows potential for application in radiomics diagnosis of RA in TMJ., (© 2022. The Author(s) under exclusive licence to Japanese Society for Oral and Maxillofacial Radiology.)

Objective: To compare volume and surface area measurements of the lateral pterygoid (LPM), medial pterygoid (MPM), and masseter muscles (MM) as calculated on magnetic resonance imaging (MRI) based on the position of the temporomandibular joint disk, mouth position, and patient sex, and to calculate the correlations of the measurements among the muscles., Study Design: Measurements of muscle volume and area were performed on the MRIs of 51 patients. Wilcoxon, Kruskal-Wallis, and Mann-Whitney U tests were used to calculate the significance of differences in measurements. The Spearman correlation coefficient calculated the correlation of measurements among the muscles. The significance of difference was established at P < .05., Results: Volume and area of the left MPM in patients with disk displacement without reduction (DDWOR) were larger than in patients with normal disk position (P ≤ .040). MM volumes were smaller with DDWOR than with DD with reduction bilaterally (P ≤ .031). The volume and area of LPM and MM were significantly different between closed and open mouth positions (P < .001). Differences in volume and area between females and males were significant for all muscles in volume (P ≤ .021) and for MPM and MM in area (P ≤ .021). Significant positive correlations were found among all muscles for volume and area., Conclusion: Volume and area measurements of the masticatory muscles varied according to disk and mouth position and patient sex and exhibited significant positive correlations., Competing Interests: Declaration of interest None., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Objectives: The aim of this study was to assess whether magnetic resonance imaging (MRI) texture features of the lateral pterygoid muscle can distinguish between rheumatoid arthritis (RA) and osteoarthritis (OA) of the temporomandibular joint (TMJ)., Methods: The authors extracted 279 texture features from 36 patients with RA and OA from the region of interest set for the lateral pterygoid muscle on short tau inversion recovery (STIR) images using MaZda Ver.3.3. A total of 10 texture features were selected using Fisher's coefficients, as well as probability of error and average correlation coefficients. Data observed to have a non-normal distribution using the Kolmogorov-Smirnov test were compared using the Mann-Whitney U-test. Receiver operating characteristic (ROC) curves were used to assess the ability of the 10 texture features to distinguish RA and OA of the TMJ., Results: A total of 10 features (5 Correlation, 3 Run Length Nonuniformity, 1 Sigma, and 1 Teta) were selected from 279 texture features. These texture features revealed significant differences between the RA and OA groups ( p < 0.01). The sensitivity, specificity, accuracy, and area under the ROC curve of the texture features for distinguishing RA from OA were 0.78-0.94, 0.89-1.0, 0.86-0.92, and 0.89-0.95, respectively., Conclusion: MRI texture analysis of the lateral pterygoid muscle may be useful for distinguishing between RA and OA of the TMJ.

Purpose: To describe the anatomic relationship of the lingual nerve with the lateral oropharyngeal structures., Methods: An anatomic dissection of the lateral oropharyngeal wall was conducted in eight sides from four fresh-frozen cadaveric heads. Small titanium clips were placed along the lingual nerve and the most anterior and medial border of the medial pterygoid muscle. Radiological reconstructions were employed for optimal visualization; the coronal view was preferred to resemble the surgical position. The distance between the lingual nerve and the medial pterygoid muscle at its upper and lower portion was measured radiologically. The trajectory angle of the lingual nerve with respect to the pterygomandibular raphe was obtained from the intersection between the vector generated between the clips connecting the upper and lower portion of the medial pterygoid muscle with the vector generated from the lingual nerve clips., Results: The mean distance from the upper portion of the medial pterygoid muscle and superior lingual nerve clips was 10.16 ± 2.18 mm (mean ± standard deviation), and the lower area of the medial pterygoid muscle to the lingual nerve was separated 5.05 ± 1.49 mm. The trajectory angle of the lingual nerve concerning to the vector that describes the upper portion of the most anterior and medial border of the medial pterygoid muscle with its lower part was 43.73º ± 11.29., Conclusions: The lingual nerve runs lateral to the lateral oropharyngeal wall, from superiorly-inferiorly and laterally-medially, and it is closer to it at its lower third., (© 2022. The Author(s).)

Purpose: The aim of this study was to evaluate the lateral pterygoid muscle (LPM) area, attachment type, signal intensity and presence of arthrosis, effusion in the temporomandibular joint (TMJ) by magnetic resonance imaging (MRI) according to the position of the articular disc., Methods: The study included a total of 126 TMJs belonging to 69 patients over the age of 18 years who had MRI due to TMJ complaints. The position of the articular disc, the area, attachment type, and signal intensity of the LPM, the presence of arthrosis on the condyle surface, and the presence of effusion in the joint space were evaluated., Results: The attachment type of the LPM did not show a statistically significant difference according to the position of the articular disc. The groups were not statistically different in terms of LPM intensity. Although the distribution of the LPM area was found to be low in the anterior disc displacement with reduction (R+DD) group and high in the anterior disc displacement without reduction (R-DD) group. It was determined that the rate of arthrosis at the condyle head was significantly higher in the R-DD group compared to the normal disc position group. The incidence of effusion was found significantly higher in the R-DD and R+DD groups than joints with normal disc position., Conclusions: Pathological changes in LPM and TMJ can be detected by MRI. In the group with R-DD, the rate of arthrosis at the condyle head, effusion, LPM area, and intensity of the Sup. LPM were higher., (Copyright © 2022 Elsevier Masson SAS. All rights reserved.)

Purpose: Lateral pterygoid muscle ossification has not been reported in condylectomy patients. This study aimed to explore the incidence, risk factors, and imaging characteristics of 38 cases with lateral pterygoid muscle ossification among 54 patients after condylectomy via intraoral approach., Methods: This retrospective study included 54 patients following simultaneous orthognathic surgery and condylectomy with coronoid process resection via intraoral approach. The authors evaluated the preoperative, 1 week, 6 months, and 1 year or more postoperative computed tomographic (CT) scans for the presence of lateral pterygoid muscle ossification and its characteristics. Sex, age at the time of surgery, disease course, affected side, preoperative alkaline phosphatase, pathology diagnosis, the height of the removed condyle, condylar shape, operator, preoperative temporomandibular joint movement, and clinical symptoms were assessed as risk factors for ossification., Results: No incidence of lateral pterygoid muscle ossification was found on preoperative CT images. Various small-size osseous masses were observed in the lateral pterygoid muscles on postoperative 6 months CT images in 38/54 patients (70.37%) after condylectomy. But no apparent enlargement of the osseous masses was found. No patients complained of clinical discomfort or functional disorder during the follow-up period (23.11 ± 13.16 months). No significant risk factors for ossification were found., Conclusions: Lateral pterygoid muscle ossification is relatively common in patients after condylectomy via intraoral approach. However, its enlargement is self-limited and remains stable 6 months after surgery. it has no adverse effects on the temporomandibular joint functional movement., Competing Interests: The authors report no conflicts of interest., (Copyright © 2022 by Mutaz B. Habal, MD.)

It has been suggested that the variations in the trajectory of the maxillary artery (MA) near the lateral pterygoid muscle (LPM) play a critical role in Botulinum neurotoxin (BoNT) injections in patients with jaw-opening/deviation dystonia (JOD). In the case of a lateral course to the LPM, an extraoral injection entails risks of MA injury, pain, and hematoma. Previous reports suggest geographical differences in variations of the MA-LPM relationship. We aimed to determine these variations in Turkish individuals and highlight the need to establish a consensus on approach to LPM injections. In 284 individuals, contrast-enhanced magnetic resonance angiography (MRA) images were evaluated by two radiologists on both sides for the variations in the course of the MA in the infratemporal fossa. Images of 44 were excluded due to trauma, arteriovenous malformation, mass, surgery, and imaging artifacts. Of the included, 62.1% were female. In 480 evaluations of 240 individuals, the MA passed lateral to the LPM in 65.6% (n = 315). No sex difference was noted. In 51 individuals (21.3%), the MA course differed on the right and left sides (medial-lateral asymmetry). These results confirm that the lateral course of the MA is more frequent. In patients with JOD, the trajectory of the MA should be determined with imaging prior to extraoral BoNT injections. In the case of a lateral course, an intraoral approach seems to be safer to avoid a potential MA injury., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Objective: Occlusal alteration due to tooth loss may cause overload of masticatory muscle and promote muscle dysfunction. This study explored the feasibility of using functional magnetic resonance imaging (fMRI) to evaluate muscle dysfunction in an established unilateral exodontia animal model., Methods: 6 rabbits were extracted right maxillary molars. T2 mapping, T2* mapping and Iterative Decomposition of water and fat with Echo Asymmetry and Least Square Estimation (IDEAL-IQ) were performed one day before extraction and every 2 weeks (2th~12th week) after extraction. The T2 and T2* values and fat fraction (FF) of bilateral temporal muscle (TM), masseter muscle (MM) and medial pterygoid muscle (MPM) were measured and compared between the extraction side and the contralateral side. Parameters of three monitoring time points (0th, 6th, 12th week) were also analyzed., Results: T2 values of MM on extraction side were significantly higher than those of contralateral side-from fourth week to 12th week after extraction ( p < 0.05). T2 values of MM and MPM on extraction side and TM on contralateral side were significantly higher in 12th week than those in 0th week ( p < 0.05). And FF of bilateral MM was significantly higher in 12th week than those in 0th week ( p < 0.05). T2* value showed no significant difference between extraction side and contralateral side and also at above three time points., Conclusion: T2 and T2* value and FF can be used as indicators of masticatory muscle dysfunction. fMRI is expected to be a non-invasive method for in vivo and real-time evaluation of masticatory muscle functional abnormality.

Objective : This study explored the effect of qat chewing (QC) on the lateral pterygoid muscle (LPM), using magnetic resonance imaging (MRI). Methods : Forty qat chewers (QG), divided into three subgroups, according to duration of QC, and 20 non-qat chewers (NQG) were included. MRI sections were obtained to assess hypertrophy and atrophy of the superior belly (SB) and inferior belly (IB) of the LPM on the chewing and contralateral non-chewing side. Results : There was a significantly higher prevalence of atrophy of the IB ( p < 0.001) and hypertrophy of the SB and IB ( p = 0.002) in the QG. Hypertrophy of SB and IB was marked ( p = 0.001) on the chewing side. Conversely, SB atrophy was marked on the non-chewing side ( p = 0.003). MRI demonstrated a positive correlation between LPM alterations and the duration of QC in subgroup analysis. Conclusion : Unilateral QC might be a cause of LPM alterations.

Background: Pathological alterations of lateral pterygoid muscle (LPM) are implicated in temporomandibular joint anterior disk displacement (ADD). However, quantification of the fatty infiltration of LPM and its correlation with ADD have rarely been reported. The aim of this study was to evaluate the fatty infiltration, morphological features and texture features of LPM in patients with ADD using T1-weighted Dixon sequence., Methods: This retrospective study included patients who underwent temporomandibular joint MRI with T1-weighted Dixon sequence between December 2018 and August 2020. The temporomandibular joints of the included patients were divided into three groups according to the position of disk: Normal position disk (NP) group, Anterior disk displacement with reduction (ADDWR) group and Anterior disk displacement without reduction (ADDWOR) group. Fat fraction, morphological features (Length; Width; Thickness), and texture features (Angular second moment; Contrast; Correlation; Inverse different moment; Entropy) extracted from in-phase image of LPM were evaluated. One-way ANOVA, Welch's ANOVA, Kruskal-Wallis test, Spearman and Pearson correlation analysis were performed. Intra-class correlation coefficient was used to evaluate the reproducibility., Results: A total of 53 patients with 106 temporomandibular joints were evaluated. Anterior disk displacement without reduction group showed higher fat fraction than normal position disk group (P = 0.024). Length of LPM was negatively correlated with fat fraction (r = -0.22, P = 0.026). Angular second moment (ρ = -0.32, P < 0.001), correlation (ρ = -0.28, P = 0.003) and inverse different moment (ρ = -0.27, P = 0.005) were negatively correlated with fat fraction, while positive correlation was found between entropy and fat fraction (ρ = 0.31, P = 0.001). The intra-class correlation coefficients for all values were ranged from 0.80 to 0.97., Conclusions: Patients with ADDWOR present more fatty infiltration in the LPM compared to NP or ADDWR patients. Fatty infiltration of LPM was associated with more atrophic and higher intramuscular heterogeneity in patients with ADD. Fat fraction of LPM quantitatively and noninvasively evaluated by Dixon sequence may has utility as an imaging-based marker of the structural severity of ADD disease process, which could be clinical helpful for the early diagnose of ADD and predication of disease progression., (© 2022. The Author(s).)

Objective: This study aimed to explore the feasibility of functional evaluation of the lateral pterygoid muscle (LPM) using diffusion tensor imaging (DTI) in patients with temporomandibular joint disorders (TMDs)., Materials and Methods: A total of 119 patients with TMD (23 male and 96 female; mean age ± standard deviation, 41 ± 15 years; 58 bilateral and 61 unilateral involvements for a total of 177 joints) and 20 healthy volunteers (9 male and 11 female; 40 ± 13 years; 40 joints) were included in this prospective study. Based on DTI of the jaw in the resting state, the diffusion parameters, apparent diffusion coefficient (ADC), fractional anisotropy (FA), λ1, λ2, and λ3 of the superior and inferior heads of the LPM (SHLPM and IHLPM) were measured. Patients with TMD with normal disc position (ND), anterior disc displacement with reduction (ADWR), and anterior disc displacement without reduction (ADWOR) were compared., Results: Patients with TMD overall, and ADWR and ADWOR subgroups had significantly higher ADC, λ1, λ2, and λ3 in both the SHLPM and IHLPM than those in volunteers ( p < 0.05 for all), whereas the ND subgroup only had significantly higher ADC and λ1 ( p < 0.001). Meanwhile, significant differences in FA in the SHLPM and IHLPM were found between volunteers and ADWOR ( p = 0.014 and p = 0.037, respectively). Among the three TMD subgroups, except for λ3 and FA in the ADWR subgroup, ADWR and ADWOR subgroups had significantly higher ADC, λ1, λ2, and λ3 and lower FA than those in the ND group ( p < 0.050). There was no significant difference in diffusion variables between ADWR and ADWOR. In ADWOR, the osteoarthritis group had significantly higher λ3 and lower FA values in the IHLPM than those in the non-osteoarthritis group., Conclusion: DTI successfully detected functional changes in the LPM in patients with TMD. The unsynchronized diffusivity changes in the LPM in different subgroups of TMD signified the possibility of using diffusion parameters as indicators to identify the severity of LPM hyperfunction at various stages of TMD., Competing Interests: The authors have no potential conflicts of interest to disclose., (Copyright © 2022 The Korean Society of Radiology.)

Objective: The objective of the study is to determine the role of Lateral Pterygoid Muscle LPM in the articular disc displacement ADD, which is considered controversial due to the variations in the pattern of insertion of the Superior Lateral Pterygoid Muscle SPLM., Background: It is well understood that the superior head of the lateral pterygoid muscle has only a single insertion pattern among individuals, in which the muscle is attached to the articular disc and capsule. However, recent findings in many studies have shown a noticeable variation in the insertion pattern of the upper LPM., Methods: MRI examinations were collected at King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia. Scans of 61 patients (41 females, 20 males; mean age 33 years old) with symptoms of temporomandibular dysfunction were reviewed retrospectively. The direction of their articular disc displacement was evaluated through sagittal and coronal views in both open and closed mouth positions., Results: There was no statistical significance found between the LPM attachment types and TMJ disc position. The chi-square test also showed no significant difference between the type of LPM attachment and the condylar location. Forty-five percent of the articular discs were located between the articular eminence and the glenoid fossa. The majority of the disc displacement was in the anterior direction., Conclusion: There was no statistically significant association found between the type of LPM attachments and the direction of disc displacement., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

This retrospective case-series study aimed to elucidate the three-dimensional attachment morphometric features and to quantify the volumetric changes of the masticatory muscles following free fibular flap reconstruction of the mandibular condyle. Navigation software (iPlan, version 3.0; Brainlab) was used to perform delineation and volumetric measurement of the masticatory muscles using DICOM data. In total, 30 patients were included in this retrospective case series. In 25 cases (83.33%), the lateral pterygoid muscle achieved reattachment within 6 months postoperatively. The medial pterygoid muscles on the affected side achieved ectopic attachment in all cases. However, masseter reattachment on the affected side was achieved in only three cases. On the normal side, the volumes of lateral pterygoid muscle, medial pterygoid muscle, and masseter had recovered to almost preoperative levels at 1 year postoperatively. On the affected side, the volume of medial pterygoid muscle had decreased significantly (p = 2.4e-04) at 3 months postoperatively. The volumes of lateral pterygoid muscle and masseter showed mild decreases at 3 months postoperatively, but these were not significant (p = 0.52 and p = 0.05 for the pterygoid muscle and masseter, respectively). At 6 months after surgery, with the exception of the volume of the lateral pterygoid muscle (p = 0.06), the total volume of the masticatory muscles decreased significantly on the affected side. The volumes of lateral pterygoid muscle, medial pterygoid muscle, and masseter showed significant decreases at 1 year postoperatively (p = 0.03, p = 4.7e-08, and p = 1.1e-05, respectively) on the affected side. The postoperative volumes of the masseter, medial pterygoid, and lateral pterygoid muscles showed significant decreases due to the loss of reattachment. The results of this study may not help to ascertain whether reattachment of masticatory muscles will lead to better function. As a consequence, clinical trials of higher quality are needed., Competing Interests: Declaration of competing interest None., (Copyright © 2021 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.)

The aim of the study was to examine lateral pterygoid muscle (LPM) and temporomandibular joint (TMJ) disc before and after Le Fort I osteotomy with and without intentional pterygoid plate fracture and sagittal split ramus osteotomy (SSRO) in class II and class III patients. Le Fort I osteotomy and SSRO were performed in class II and class III patients. LPM measurements using oblique sagittal computed tomography (CT) images and TMJ disc position using magnetic resonance imaging (MRI) were examined. Statistical comparisons were performed for the LPM and TMJ between class II and class III patients and between those with and without intentional pterygoid plate fracture in Le Fort I osteotomy. The subjects comprised 60 female patients (120 sides), with 30 diagnosed as class II and 30 as class III. Preoperatively, the width of the condylar attachment, width at eminence, length of the LPM, angle of the LPM, and square of the LPM were significantly smaller in the class II group than in the class III group (p < 0.05). After 1 year, the width of the condylar attachment, width at eminence, and angle of the LPM remained significantly smaller in the class II group than in the class III group (p < 0.0001). TMJ disc position was significantly related to the width of the condylar attachment of the LPM, both pre- and postoperatively (p < 0.0001). However, postoperative disc position did not change in all patients. Next, the class II patients (60 sides) were divided into two groups who underwent Le Fort I osteotomy with or without intentional pterygoid plate fracture. Changes in all measurements of the LPM showed no significant differences between these two groups. Our study suggested that TMJ disc position classification could be associated with the width of condylar attachment of the LPM before and after surgery, while the surgical procedure, including Le Fort I osteotomy with intentional pterygoid plate fracture, might not affect postoperative LMP or disc position in class II patients., Competing Interests: Declaration of competing interest None declared., (Copyright © 2021 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.)

The purpose of this study was to explore the status of the lateral pterygoid muscle (LPM) after detachment in artificial temporomandibular joint replacement (TJR) surgery. Patient clinical and computed tomography imaging data were collected before and after unilateral artificial TJR with LPM detachment. The volume of the LPM on the operated and unoperated sides was measured before and after surgery (at 1, 3, 6, 12 months) using ProPlan CMF 3.0 software. The volumes of the LPM on both sides, the patient's mandibular movements, quality of life (QoL), and pain and diet scores (visual analogue scales) were evaluated and compared at the different follow-up stages. Ten patients were included in the study. After surgery, the volume of the operated LPM was significantly reduced to 60.78% at 3 months (P=0.007), and gradually stabilized to 51.58% at 6 months (P=0.025) and 54.68% at 1 year postoperative (P=0.002). There were no significant LPM volume changes on the unoperated side (P=0.67). Lateral movement of the operated joint was significantly reduced (P=0.021) and correlated with the LPM volume change after surgical detachment (P=0.042). The LPM shrank after detachment in the artificial TJR surgery and the muscle detachment affected the movement of the replaced joint., (Copyright © 2021 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

Background : The pterygoid fovea on the mandibular neck is superomedial to the mandibular notch and serves to attach the lateral pterygoid muscle. Clinical presentation : During a retrospective cone beam computed tomography study, a 67-year-old male patient was found to exhibit a peculiar variant that contradicted normal anatomy. The patient's mandibular condyles were asymmetrical in terms of their shapes and sizes, although their lateral poles (lateral condylar tubercles) were both prominent. On the left side, the lateral condylar tubercle had a second, or accessory, pterygoid fovea, which was located outside the mandibular notch. Further, the left lateral pterygoid muscle was attached to the entire width of the mandibular condyle, including the accessory fovea. Clinical significance : Such rare anatomical variants lead to asymmetrical temporomandibular joints, although their occurrence has not previously been reported. Thus, they should be further documented in clinical studies of temporomandibular joint dysfunction. Abbreviations: LPM: Lateral pterygoid muscle; MC: Mandibular condyle; PF: Pterygoid fovea; TMJ: Temporomandibular joint; MCC: Mandibular condylar cartilage; MPR: Multiplanar Reconstruction; VC: Vascular canal.

Objective To evaluate lateral pterygoid muscle(LPM)contraction in the patients with temporomandibular disorders(TMD)based on 3D-T2 weighted imaging(3D-T2WI).Multiplanar reconstruction(MPR)was employed to measure the length of LPM in the images taken in closed-and open-mouth positions. Methods Seventeen TMD patients [age of(29.82±10.70)years,males/females=8/9] and 13 normal volunteers [control,age of(23.54±3.31)years,males/females=6/7] received 3D-T2WI of the temporomandibular joints in closed-and open-mouth positions from November 2019 to April 2020 in Department of Radiology,Hainan Hospital of Chinese PLA General Hospital.According to the position of the discs,the subjects were classified into the following groups:TMD with disc displacement without reduction(TMD-DDwoR),TMD with disc displacement with reduction(TMD-DDwR),TMD without disc displacement(TMDwoDD),and normal control without disc displacement(NCwoDD).MPR was employed to measure the maximal length of the superior belly of LPM.One-way analysis of variance,receiver operating characteristic curve,and permutation test were employed for the statistical analyses. Results The contraction of LPM was significantly shorter in TMD-DDwoR group [(3.36±1.96)mm] than in TMDwoDD group [(7.90±3.95)mm],NCwoDD group [(8.77±3.13)mm]( F =12.891, P =0.000),and TMD-DDwR group[(7.12±3.69)mm]( χ 2 =5.314, P =0.031). Conclusion This study confirmed that the contraction of LPM decreased in patients with TMD-DDwoR,which provided imaging evidence for the study of disc displacement mechanism in TMD patients.

Aim: The aim of this study was to determine the lateral pterygoid muscle (LPM) in relation to preauricular skin measured from computed tomography (CT) scan measurements., Materials and Methods: CT scans of 160 patients aged between 18 and 75 years were retrospectively collected and analyzed, and the distances were measured to determine the location of the LPM center in relation to the preauricular skin. On axial CT crossing the maximum muscle width, two lines [the first line is below the center of the zygomatic arch (first position), while the second line was 5 mm posterior to the first one (second position)] were drawn from the preauricular skin to the medial border and then extended to the lateral border of the muscle. These measurements were used to calculate the distance to the center of the muscle mathematically. Data were statistically analyzed, and the differences between both genders and both sides were investigated. The level of significance was set at p -value <0.05., Results: Males displayed larger mean values in two positions (36.6 ± 2.25 and 35.97 ± 4.19, respectively) than females (33.66 ± 4.46 and 32.80 ± 3.21, respectively). The difference between both genders was found to be statistically significant. Measurements on the right side were also larger than those on the left side, but with no significant difference., Conclusion: LPM center can be approached safely in males by inserting the needle about 36 mm at the first position and 33 mm at the second position. However, in females, these distances are located 3 mm shorter in both positions., Clinical Significance: The outcome of this study will provide the clinicians with measurements that can help in directing the needle or electromyography (EMG) electrode during the extraoral injection technique of the LPM. How to cite this article: Al-Tairi NH, Al-Sharaee YA, Alhajj MN. Lateral Pterygoid Muscle Location in Relation to Preauricular Skin Measured from CT Scans among a Sample of Yemeni Adults. J Contemp Dent Pract 2021;22(5):522-526.

Objectives: The purpose of this study was to examine changes in lateral pterygoid muscle and temporomandibular joint (TMJ) disc position in classes II and III patients, before and after bi-maxillary surgery., Materials and Methods: The subjects were comprised of 48 patients (96 sides), 23 of whom were diagnosed as class II and 25 as class III patients who underwent Le Fort I osteotomy and sagittal split ramus osteotomy (SSRO). The cross-sectional measurements of the lateral pterygoid muscles were measured at two levels of horizontal plane images (condyle and mandibular notch levels) by computed tomography (CT), before and 1 year after the operation. The relationship between these measurements regarding lateral pterygoid muscle and disc position by magnetic resonance image (MRI) was also examined statistically., Results: Preoperatively, class II was significantly larger than class III in condylar angle at the upper level and in long diameter, square, condylar angle, and muscle angle at the lower level (P < 0.05). After 1 year, class II was significantly larger than class III in condylar angle, long diameter, and muscle angle at the upper level and in long diameter, short diameter, square, condylar angle, and muscle angle at the lower level (P < 0.05). TMJ disc position classification correlated significantly with condylar angle at the upper level and long diameter and condylar angle at the lower level (P < 0.0001)., Conclusion: This study suggested that there were differences in the cross-sectional measurements of the lateral pterygoid muscles between class II and class III patients, before and after bi-maxillary surgery.

Objective: To compare the size of Ostmann's fat pad (OFP) between healthy ears and ears with chronic otitis media with cholestatoma (COMwC) using magnetic resonance imaging (MRI)., Methods: Twenty-six patients with unilateral COMwC underwent mastoidectomy. Pre-operative MRI records were reviewed retrospectively. The healthy ears served as the control group. OFP is represented by the maximum diameter of the high intensity area medial to the tensor veli palatini muscle (TVP); M1. A reference diameter was defined from the medial border of OFP reaching the medial border of the medial pterygoid muscle; M2. Values of M1, M2 and the ratio of M1:M2 was compared between the healthy and pathological ear in each patient., Results: All 26 patients (16 females,10 males) had unilateral cholestatoma. Mean age was 37.6 years (range 19-83). In the healthy ( H ) ears group, mean M1 H was 2.04 ± 0.53 mm, mean M2 H was 9.57 ± 2.57 mm.In the pathological ( P ) ears group; mean M1 P was 2.03 ± 0.55 mm, mean M2 P was 9.86 ± 2.37 mm. A comparison of M1 and M2 values between the healthy and pathological ear groups was not statistically significant ( P  = .853 and P  = .509, respectively).Mean M1 H :M2 H ratio in the healthy ears group was 0.22 ± 0.05, mean M1 P :M2 P ratio in the pathological ear group was 0.21 ± 0.06. A comparison between these ratios found no significant statistical correlation ( P  = .607)., Conclusion: The size of Ostmann's fat pad does not affect the development of chronic otitis media with cholestatoma in adults.

Objective: The aim of the present study was to evaluate the accuracy of an extraoral CBCT-planned 3D-printed surgical guide aimed to percutaneous injection of substances into the temporomandibular joint (TMJ) and the lateral pterygoid muscle (LPM)., Methods: Nine human cadaver heads were used. Pre-planning CBCT and facial scans were obtained and three percutaneous injection sites were planned: one for the lower compartment of the TMJ and two for the LPM. A digital surgical guide was then designed with small titanium sleeves and printed by a 3D printer. After the injections, new CBCT scans with the needles in place were obtained in order to assess the accuracy of the procedure in relation to the virtual planning., Results: The mean values for angle deviation were very low (range 1.13 o -4.08 o ), the same happening for the mean difference in the length reached (range 1.82-2.64 mm), as well as for the mean difference in the needle tip dislocation (range 0.94-2.03 mm)., Conclusion: The guide seems to be a reliable tool for accurate percutaneous injection of drugs into the inferior compartment of the TMJ and the LPM. Further studies are necessary to test the efficacy and validate the method in an in vivo study.

Objectives: The aim of this study was to evaluate lateral pterygoid muscle (LPM) signal intensity changes related to different degrees of disc status groups using magnetic resonance imaging (MRI)., Methods: Four groups were established according to disc displacement of examined temporomandibular joint (TMJ) and opposing TMJ. MRI scans were obtained with a 1.5 T device. The signal intensity was measured from the sagittal slice where midportion of the muscle belly was observed. The regions of interest were placed over the superior and inferior heads of LPM. To normalize differences in signal intensity, signal intensity of the grey matter and white matter of the brain was also measured. Signal intensity ratio (SIR) was calculated. Measurements were performed in both T1- and T2-weighted images., Results: In the intergroup comparisons, a statistically significant difference was found for SIR1 sup., SIR1 inf., SIR2 sup. and SIR2 inf. variables (p < 0.01). According to multiple comparison test (Tukey), no significant difference was found between group 0 and group 1 for SIR1 sup., SIR1 inf., SIR2 sup. and SIR2 inf. variables (p > 0.05). For SIR1 sup., SIR1 inf., SIR2 sup. and SIR2 inf. variables, significant differences were found between five binary comparison groups (1-2, 1-3, 2-3, 0-2, 0-3) (p < 0.05)., Conclusion: In conclusion, SIR is correlated with the degree of disc displacement. The internal derangement of the opposite joint did not affect SIR of superior and inferior heads of examined LPM in both T1- and T2-weighted images. The inferior head of LPM was also found affected by disc displacement.

Objective: To evaluate the functional changes of lateral pterygoid muscle (LPM) in the patients with temporomandibular disorders (TMD) using histogram texture analysis. Methods: A total of 28 TMD patients, including 15 males and 13 females, aged (26.2±12.1) years (15-62 years), were enrolled in the outpatient clinic of Department of Radiology, Hainan Hospital of Chinese PLA General Hospital from May 2016 to April 2020. At the same time, 13 volunteers with normal temporomandibular joint [6 males and 7 females, aged (23.5±3.3) years (20-30) years] were recruited. All participants were performed with temporomandibular joint MRI scan, and the subjects were classified into 3 groups according to the disc displacement: TMD with disc without displacement (TMD-DwoD), TMD with disc displacement without reduction (TMD-DDwoR) and NC with disc displacement without reduction (NC-DwoD) for each temporomandibular joint. The area, signal intensity, coefficient of variation (CV) of mean signal intensity and histogram texture of the superior belly of LPM (SBLPM) and inferior belly of LPM (IBLPM) were measured using regions of interests. Results: The area of SILPM presented significantly smaller in TMD-DwoD [(67.36±30.23) mm 2 ] compared with that in NC-DwoD [(91.42±45.01) mm 2 ] ( P <0.05) and in TMD-DDwoR group [(72.27±37.53) mm 2 ] ( P >0.05). The mean signal intensity of SBLPM was identified significantly higher in TMD-DwoD (304.20±29.90) and TMD-DDwoR (315.06±40.20) compared with that in NC-DwoD (269.79±25.54) ( P <0.05). The CV of mean signal intensity of SBLPM presented significantly higher in TMD-DwoD (8.89±2.60) compared with that in NC-DwoD (6.76±1.82) and TMD-DDwoR (7.63±1.62) ( P <0.05). The skew and kurtosis showed no significantly differences among three groups for SBLPM ( P >0.05). The mean signal intensity and CV for IBLPM presented significantly higher in TMD-DwoD (286.69±23.48 and 9.96±2.24, respectively) and TMD-DDwoR (275.98±30.55 and 10.25±1.96, respectively) compared with that in NC-DwoD (243.56±17.04 and 8.49±1.94, respectively) ( P <0.05). The skewness showed significantly lower in TMD-DwoD (0.90±0.94) and TMD-DDwoR (0.73±0.97) compared with that in NC-DwoD (1.40±1.03) ( P <0.05). The area and kurtosis for IBLPM showed no significant differences among three groups ( P >0.05). Conclusions: The MR histogram texture analysis could primarily be considered as a tool to evaluate the LPM function in TMD patients.

Purpose: Pterygoid process fractures (PPFs) are classically associated with Lefort fractures but can also be encountered in association with other facial fractures such as mandibular fractures. The aim of this study was to estimate the frequency of PPFs associated with mandibular fractures and identify factors associated with PPF., Materials and Methods: We conducted a retrospective cross-sectional study using computed tomography scanning of patients having a mandibular fracture between November 2018 and April 2020. PPFs were classified using the classification by An et al. Volume, length, and width of both lateral pterygoid muscles have been evaluated by using an image processing software. Study population has been divided into 2 groups: fracture of pterygoid process or the absence of PPF. To evaluate the implication of lateral pterygoid muscle in the pathophysiology of PPF, we compared lateral pterygoid muscle volume, its maximal length, and width between both groups. Patients with bilateral fractures were excluded from this analysis., Results: About 304 patients with at least 1 mandibular fracture have been included in this study. About 18 patients presenting an association of mandibular fracture and PPF were finally selected. About 83.33% of the patients were concerned by a fracture of the posterior part of the mandible. The PPF was classified as type IIA by the classification of An et al for 94.4% of patients. The lateral pterygoid muscle volumes were significantly larger on the side of the PPF (P = .02). However, there were no significant differences in the maximum length (P = .49) and width (P = .1) of lateral pterygoid muscle., Conclusions: Our study showed an association between mandibular fractures (mainly ipsilateral posterior) and isolated PPF through a lateral pterygoid muscle volume increase., (Copyright © 2020 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

The aim of this study was to examine the lateral pterygoid muscle (LPM) parenchyma, myotendinous junction, and tendon in temporomandibular disorder (TMD) patients using 3T magnetic resonance imaging (MRI). Results were compared with findings reported in the literature, in which the LPM has been attributed a major role in triggering TMD. 3T MRI was used for temporomandibular joint (TMJ) imaging. The MRI images of 63 patients were analysed for muscle contracture and atrophy, tendon rupture, signal alterations of the tendon, tendon contrast enhancement, and peritendinous fluid collection. Descriptive statistics and the coefficient estimate method were used for statistical analysis. Focus was placed on the association between LPM tendon pathology and TMJ lesions like osteoarthritis and disc displacement. Severe lesions of the LPM tendon and muscle parenchyma, like rupture or fibrosis, were detected in very few cases. Only moderate signs of tendinosis were found in TMD patients. In contrast, there was a clear correlation between tendon lesions and osteoarthritis or anterior disc displacement. These results indicate the need to discuss and question the role of the LPM and its tendon in TMD. Data suggest that LPM and tendon lesions are part of complex degenerative changes of the TMJ, and it seems less likely that a LPM disorder is causative in TMD., (Copyright © 2020 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

Aim: To investigate the imaging features of chondrosarcoma of the temporomandibular joint (TMJ) and review the literature., Materials and Methods: Computed tomography (CT), magnetic resonance imaging (MRI), and integrated positron-emission tomography (PET)/CT images of nine patients with histopathologically confirmed chondrosarcoma of the TMJ were reviewed retrospectively. Imaging features regarding the direction of lesion growth, bone destruction, infiltration into the tendon of the lateral pterygoid muscle (LPM) in the pterygoid fovea, enhancement pattern, calcification, periosteal reaction, markedly hyperintense T2 signal area, and qualitative PET signal intensity were evaluated., Results: Seven of nine patients (77.8%) presented with lesion growth that was outward from the medulla of the mandibular condyle. Infiltration into the tendon of LPM in the pterygoid fovea was observed in all cases, and 77.8% (7/9) of them demonstrated >50% infiltration. All the lesions showed a mixed peripheral and internal enhancement, and revealed a markedly hyperintense T2 signal intensity area, which showed no enhancement. Although five of nine cases demonstrated higher FDG uptake compared with that of the liver, the other four cases showed less FDG uptake than that of the liver., Conclusion: Chondrosarcoma of the TMJ demonstrated several imaging features, including outward growth from the mandibular condyle, resultant infiltration into the tendon of LPM in the pterygoid fovea, various patterns of internal enhancement, and a markedly hyperintense T2 signal intensity area. These imaging features may be helpful to differentiate chondrosarcoma from other lesions of the TMJ., (Copyright © 2020 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Objectives: To compare the volume and voxel intensity of articular disc and lateral pterygoid muscle (LPM) between a group of migraine patients and a control group (those without history of headache) by using magnetic resonance imaging (MRI). Patients and methods: MRI scans of 17 migraine patients and 15 healthy controls subjects were analysed and processed, using ITK-SNAP software, by a single investigator, for calculation of volumes and voxel intensity of articular disc and superior and inferior head of LPM. Results: There were statistically significant differences between migraine patients and controls regarding the volume and voxel intensity of articular disc and inferior head of LPM, increasing in migraine patients. Intra-rater was highly consistent and reproducible (intra-class correlation coefficient [ICC] = 1). Conclusions: Higher voxel intensity in disc and inferior head of LPM of MRI scans was linked to the increased volume of articular disc, inferior head of LPM and migraine.

Background: Texture features were the intrinsic properties of the human tissues and could efficiently detect the subtle functional changes of involved tissue. The pathologic changes of the lateral pterygoid muscle (LPM) were significantly correlated with the temporomandibular disc displacement. However, the occult functional changes of LPM could not be detected by the naked eye on the medical images. The current study was aimed to evaluate the functional changes of the LPM in the patients with temporomandibular disorders (TMDs) using texture analysis., Methods: Twenty-nine patients with TMD were performed with magnetic resonance (MR) imaging on a 3.0T MR scanner, who were consecutively recruited from the TMD clinic of Hainan Hospital of Chinese People's Liberation Army General Hospital from February 2019 to September 2019. The patients were classified into three groups according to the disc displacement: disc without displacement (DWoD), disc displacement with reduction (DDWR) and disc displacement without reduction (DDWoR). The gray-level co-occurrence matrix method was applied with the texture analysis of LPM on the axial T2-weighted imaging. The texture features included angular second moment, contrast, correlation, inverse different moment, and entropy. One-way analysis of variance was used for grouped comparisons and receiver operating characteristics (ROC) curve analysis was applied to evaluate the diagnostic efficacy of the texture parameters., Results: Texture contrast of LPM presented significantly lower in DDWoR (46.30 [35.03, 94.48]) than that in DWoD (123.85 [105.06, 143.23]; test statistic = 23.05; P < 0.001). Texture entropy of LPM showed significant differences among DWoD (7.62 ± 0.33), DDWR (6.76 ± 0.35), and DDWoR (6.46 ± 0.39) (PDWoD-DDWR < 0.001, PDWoD-DDWoR < 0.001, and PDDWR-DDWoR = 0.014). Area under the ROC curve (AUC) demonstrated that texture entropy had an excellent diagnostic accuracy for DWoD-DDWR (AUC = 0.96) and DWoD-DDWoR (AUC = 0.98)., Conclusion: The texture contrast and entropy could identify the altered functional status of LPM in patients with TMD and could be considered as the effective imaging biomarker to evaluate the functional changes of LPM in TMD.

Objective: The aim of this study was to analyse the volumetric and crossectional parameters of masseter and medial pterygoid muscles in the relation with mandibular skeletal morphology in individuals with different underlying growth patterns in the vertical dimension., Material and Methods: The study originally involved 76 individuals with definite clinical and radiological criteria: 31 skeletal Class III and 26 skeletal Class II patients before the orthognathic surgery and 20 skeletal class I (normal) individuals with complaints of wisdom teeth and associated medical problems. On the basis of cephalometric measurement of the mandibular plane and sella-nasion (MP-SN), the study sample was categorised according to the vertical facial dimension in 3 different growth pattern subgroups: 19 subjects with horizontal growth pattern, 25 subjects with vertical growth pattern and 33 subjects with neutral growth pattern. MRI was performed for the masseter and medial pterygoid muscles, and volume and cross-sectional area measurements were performed. Cone beam computed tomography (CBCT) investigation was performed for the assessment of craniofacial structures and the following measurements of the mandibular parameters were obtained: height of ramus, length of mandibular corpus, overall mandibular length, inter-angular width and intercondylar width., Results: There were statistically significant differences among all study groups regarding masseter volume (p<0.006) and CSA (p<0.006), with the highest values in the horizontal growth pattern group and the lowest values in vertical growth pattern group. After Bonferroni correction, statistically significant difference (p<0.004 and p<0.008) was noted between the horizontal and vertical growth pattern groups, respectively. A similar tendency was observed for the medial pterygoid, but with no statistical significance. A statistically significant negative correlation was observed between MP-SN and the volume of masseter and medial pterygoid in the overall sample. Of the seven muscular and mandibular variables included in the regression analysis, the final model included only four variables that were significantly associated with MP-SN and explained 37% of its variance (masseter volume (p=0.017), mandibular overall length (p<0.001), height of mandibular ramus (p=0.003), and length of mandibular corpus (p<0.001))., Conclusions: The masseter muscle seems to be more sensitive to the variation in mandibular morphology than the medial pterygoid muscle, and volume as the biomechanical characteristic seems to be a more significant parameter of the size of the interaction with vertical skeletal growth patterns.

Objectives: To investigate the olfactory fossa depths and lateral lamella lengths of patients with different types of developmental disorders of paranasal sinuses in comparison with normal controls., Study Design: Retrospective, archival, radio-anatomical study., Methods: We included 58 patients with maxillary sinus hypoplasia, 50 patients with frontal sinus hypoplasia/aplasia, 50 patients with sphenoid sinus hypoplasia/aplasia, and 40 normal controls. Reviewing paranasal computerized tomography scans, we noted the olfactory fossa depths and lateral lamella lengths of all the groups and compared between the hypoplasia groups and the control group., Results: Compared with the normal controls, the maxillary hypoplasia group (P < 0.001), frontal hypoplasia/aplasia group (P = 0.004), and sphenoid hypoplasia/aplasia group had significantly deeper olfactory fossa (P = 0.003). The mean lateral lamella lengths in the type 1, type 2, and type 3 hypoplastic maxillary sinus groups were significantly greater compared with that in the control group (P < 0.001). Additionally, the mean lateral lamella lengths in the hypoplastic frontal sinus, aplastic frontal sinus, and hypoplastic sphenoid sinus groups were significantly greater compared with that in the control group (P < 0.001)., Conclusion: The patients with pneumatization defects of the maxillary, frontal, and sphenoid sinuses had deeper olfactory fossa and longer lateral lamella related to increased risk of skull base injury during endoscopic sinus surgery., Level of Evidence: 3 Laryngoscope, 129:2458-2463, 2019., (© 2019 The American Laryngological, Rhinological and Otological Society, Inc.)

Myositis ossificans (MO) is a rare non-neoplastic disorder characterized by heterotopic ossification in soft tissues, mainly muscles. MO traumatica is characterized by ossification of the soft tissues after acute or repetitive trauma, burns, or surgical intervention. Muscular or soft tissue trauma is usually present as the underlying etiology. MO traumatica usually involves the extremity muscles. The number of reported cases involving the masticatory muscles is extremely low. The most common clinical sign of this condition is progressive limitation of mouth opening. Surgical resection of the ossified tissue has been the most commonly used treatment for this disorder, with a high postoperative recurrence rate. We report a case of traumatic MO of the medial pterygoid muscle to draw attention to the possibility of the condition in patients with a limited mouth opening and to review the reported data about MO traumatica involving the medial pterygoid muscle., (Copyright © 2018 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

Background and Objectives: We aimed to describe a novel technique of ultrasound-guided selective mandibular nerve block with a lateral pterygoid plate (LPP) approach and to assess its feasibility and accuracy in a soft cadaver model., Methods: Ten soft cadavers were studied. A curved array ultrasound transducer was applied over 1 side of the face of the cadaver, in an open-mouth position. The transducer was placed transversely below the zygomatic arch and tilted in the caudal-to-cranial direction to identify the boundary of the LPP. The needle was inserted in-plane, in an anterior-to-posterior direction, into the posterior border of the uppermost part of the LPP, and 3 mL of methylene blue was injected., Results: Mandibular nerve block was successfully performed in all 10 cadavers using an LPP approach under ultrasound guidance. The mandibular nerve and its branches were seen to be stained with methylene blue in all cadaveric specimens. No accidental injection into the facial nerve or maxillary artery was observed., Conclusions: This cadaveric study suggests that this novel technique, using an LPP approach under ultrasound guidance, is helpful for selective mandibular nerve block, with high accuracy and feasibility. Further studies are required to establish its safety and efficacy for clinical application., Clinical Trial Registration: This study was registered at the Thai Clinical Trials Registry (ClinicalTrials.in.th), identifier TCTR20160601004.

Introduction: Meckel's cave is a dural-lined cavity in the middle fossa skull base in which lies the Gasserian ganglion, a potential site for tumors and inflammatory lesions. A variety of lesions can be predominantly isolated to Meckel's cave, including extension from head and neck cancers, other malignant tumors, as well as benign lesions. Clinical presentation and imaging findings are often insufficient to establish a diagnosis. Hence, histologic confirmation is required to determine the appropriate treatment strategy. Several surgical approaches have been used to reach this deep-seated area, often with significant morbidity and prolonged recovery. Given advancements in endoscopy and greater facility with the technique, the endoscopic endonasal approach has been used increasingly to reach lesions in the region., Methods: A single-institution, retrospective chart review over a 10-year period was performed to identify and describe patients with pathologically differing but imaging-similar lesions with their epicenter in Meckel's cave., Results: Of a total of 21 cases of lesions in Meckel's cave approached by an endoscopic endonasal transpterygoid approach, we present 6 patients with imaging-ambiguous lesions involving Meckel's cave that were biopsied via the extended endoscopic endonasal approach. Among this diverse group, pathology included B-cell lymphoma, squamous cell carcinoma, adenocarcinoma, malignant schwannoma, benign schwannoma, and neurosarcoidosis., Conclusions: We explore not only the relevance of this approach in the armamentarium of the modern skull-base surgeon but also its limitations and conclude that the endoscopic endonasal approach provides a safe and relatively direct, minimally invasive corridor to many lesions of Meckel's cave., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Objective: To review the results of sphenoid sinus lateral recess (SSLR) cerebrospinal fluid (CSF) leaks treated with the endoscopic endonasal minimal transpterygoid approach (EEMTPA) and to discuss the surgical technique and outcomes., Methods: We performed a retrospective analysis of 13 cases who underwent SSLR CSF leak repair through the EEMTPA in our clinic between September 2008 and December 2017. Demographic and etiological features with reconstruction and surgical outcomes were examined. Mean follow-up time was 6.1 years., Results: In regard to etiology, the SSLR CSF leaks included 9 patients with spontaneous, 2 patients with traumatic, and 2 with iatrogenic causes. CSF leak was at the left lateral recess in 8 cases and at right lateral recess in 5 cases. Nine patients had empty sella syndrome, and 11 patients had meningoencephaloceles in addition to SSLR CSF leaks. All patients underwent surgery through the EEMTPA, and a multilayer closure with tissue overlay grafts were used for reconstruction. A pedicled nasoseptal flap and/or pedicled middle turbinate flap were applied to the area of the leak in all cases. One patient had a persistent CSF leak and another had recurrence, both of which required revision surgery. Our overall success rate was 100%., Conclusions: EEMTPA is a safe and effective method that can be used to treat challenging pathologies at the SSLR, including CSF leaks accompanying meningoencephaloceles. Furthermore, the success rate of EEMTPA for SSLR CSF leaks can be increased by applying endoscopic skull base reconstruction techniques such as the pedicled nasoseptal flap and pedicled middle turbinate flap., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background and Objectives: This study aimed to describe and assess the accuracy and feasibility of a novel technique for ultrasound-guided maxillary nerve block using the lateral pterygoid plate (LPP) approach via the pterygopalatine fossa (PPF) in a soft cadaveric model., Methods: Ten soft cadavers were studied. The curved array ultrasound transducer probe was applied over 1 side of the face of the cadavers in the open-mouth posture. It was placed transversely below the zygomatic arch for identifying the border of the maxillary tuberosity and the LPP. We tilted the curve probe from the caudal to the cranial direction until the uppermost part of the PPF was identified. The in-plane needle approach was used from the anterior-to-posterior and lateral-to-medial directions through the fossa, and 3 mL of methylene blue dye was injected., Results: The spread of injectate after ultrasound-guided maxillary nerve block using the LPP approach was successfully performed in all cadavers as demonstrated by visualized moderate to marked traces of methylene blue within the PPF. No accidental injections in the maxillary arteries or facial nerves were observed., Conclusions: This cadaveric study suggests that ultrasound-guided maxillary nerve block using the LPP approach via the PPF has a high degree of accuracy and feasibility. Further studies are required to confirm its efficacy and safety for clinical application.

Objectives: To evaluate non-invasively the morphological features of both lateral pterygoid muscle (LPM) and masseter muscle by using diffusion tensor Imaging on two patients affected by mandibular asymmetry., Methods: Two female patients with mandibular excess and asymmetry who underwent Le Fort I osteotomy and bilateral sagittal split osteotomy were recruited for this study. Morphological (T 1 weighted) and diffusion weighted images were acquired with a 3T scanner 1 week before (T0) and 1 month after the surgery (T1). Probabilistic tensor-based tractography reconstruction of bilateral masseters and LPMs was performed and mean fractional anisotropy (FA) values for both muscles were extracted., Results: Diffusion tensor imaging was able to identify the muscle geometrical morphology and diffusion microstructural changes. Both at T0 and T1, mean FA values had no significant differences between the right and left side of masseter (at T0: p = 0.91; at T1: p = 0.54) and LPM (at T0: p = 0.92; at T1: p = 0.43), respectively. Both patients reported a significant improvement in FA mean values of the left LPM (p = 0.03) between T0 and T1, whereas no diffusion parameters' changes were observed for the bilateral masseter muscles and right LPM., Conclusions: We found that after the surgery the LPM ipsilateral to the deviation side showed a significant increase of FA compared to the baseline. Although preliminary, our findings suggest that diffusion tensor imaging may represent a promising tool to investigate non-invasively the masticatory muscles in temporomandibular joint disorders.

In a previous study, we used muscle functional magnetic resonance imaging to show that the anterior movement of the occlusal point increased the activity of the superior head of the ipsilateral lateral pterygoid muscle (ipsilateral SHLP) during unilateral single-tooth clenching. The purpose of this study was to verify the hypothesis that the increased activity of the ipsilateral SHLP described above serves to antagonise the occlusal force acting on the condyle. In total, 9 healthy volunteers were requested to perform left unilateral clenching at the first molar or first premolar region for 1 minute at 20% or 40% maximum voluntary clenching force. Changes in the mean proton transverse relaxation time (∆T2) were examined from the magnetic resonance images obtained before and after each clenching act as an index of the activity in all masticatory muscles. Correlation analyses of the mean ΔT2 for each volume of interest were performed with the first molar or premolar clenches to analyse the correlation between the activities in each muscle. A statistically significant correlation was exhibited between the ipsilateral temporal and ipsilateral SHLP (r = .651, P = .003) during first premolar clenching. However, no significant correlations were observed in the ipsilateral SHLP during first molar clenching. The results of this study suggest that the ipsilateral SHLP may contribute to the pulling of the mandibular condyle forward against the occlusal force generated by the ipsilateral temporal muscle., (© 2017 John Wiley & Sons Ltd.)

Objectives: Pathological changes of the lateral pterygoid muscle (LPM) have been investigated using various modalities, including magnetic resonance (MR) imaging and electromyography. Fluid-attenuated inversion recovery (FLAIR) is an MR sequence that we hypothesized can be used to evaluate abnormalities of the LPM. The purpose of this study was to analyze the FLAIR signal intensity of the LPM in painful temporomandibular joints (TMJs) and investigate the pathological changes of the muscle., Methods: The study was based on 149 TMJs of 77 patients who were referred for MR imaging of the TMJ. Patients rated their degree of pain during chewing and mouth opening using a visual analog scale (VAS). Regions of interest were placed over the superior and inferior heads of the LPM and gray matter on FLAIR sagittal images. Using the signal intensity of gray matter as a reference, the signal intensity ratio (SIR) of the LPM was calculated. Spearman's rank-correlation coefficient was used to analyze the correlation between the SIR and the VAS score (p < 0.05)., Results: A significant correlation was present between the SIR on FLAIR images and the VAS score., Conclusions: These results suggest that the FLAIR signal intensity of the superior and inferior heads of the LPM significantly increases as TMJ pain becomes more severe. Thus, FLAIR could be useful in assessing the relationship between the MR signals of the LPM and clinical symptoms.