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Objective To evaluate the effectiveness of fully guided botulinum toxin (BTX) injection in lateral pterygoid muscle (LPM) using muscle segmentation technique and compare it with electromyography (EMG) for management of symptomatic disc displacement with reduction (DDWR). Materials and methods This prospective randomized controlled trial (RCT) included 20 patients suffering from DDWR. Patients were randomly allocated to two groups receiving BTX injection in LPM using fully guided technique of muscle segmentation for LPM in group I (study) while using EMG in group II (control). Evaluation was done for disc position after 3 months and for maximum interincisal opening (MIO), temporomandibular joint (TMJ) and LPM tenderness, and clicking after 1,3 and 6 months. Results Maximum interincisal opening showed reduction at 1-month follow-up, followed by significant improvement in both groups. Significant disappearance of clicking, reduction in LPM and TMJ tenderness and disc position reduction were detected in both groups. However, the difference between both groups was not statistically significant except in LPM tenderness, there was a statistically significant difference in favor of group I at 3-and 6- month follow-up. Conclusion The findings suggest that the fully guided technique using muscle segmentation is a viable, cost-effective and reproducible alternative to EMG for BTX injection in LPM. Clinical relevance The fully guided technique by muscle segmentation in LPM is as effective as EMG, providing 3D virtual augmented environment of the muscle with its surrounding skeletal and dental structures. Trial registration This prospective RCT has been retrospectively registered at Clinical Trials.gov with identification number: NCT06633445, 2024–10-01.

This study aimed to investigate angular changes in the temporomandibular joint (TMJ) associated with anterior disc displacement (ADD) through axial magnetic resonance imaging (MRI). Specifically, the lateral pterygoid muscle (LPM) attachment angle and the condylar position angle were evaluated using a coordinate-based vector analysis method. A total of 151 patients and 302 TMJs were retrospectively evaluated. Joints were categorized into three groups: healthy, ADD with reduction (ADDwR), and ADD without reduction (ADDwoR). On axial MRI slices, angular measurements were obtained using a pixel-based coordinate system and calculated using the dot product method. Intra-observer reliability was assessed using intraclass correlation coefficients (ICCs). Measurement reliability was high (ICC = 0.965 for LPM angle, ICC = 0.969 for condylar angle). No significant differences were found in LPM angle between groups ( p  = 0.51). In contrast, condylar position angle was significantly lower in both ADD groups compared to healthy joints ( p  = 0.01). No statistically significant difference was observed between the ADDwR and ADDwoR groups. A significant decrease in condylar position angle was observed in joints affected by ADD, possibly indicating adaptive joint remodelling over time. However, no angular change was observed in the attachment angle of the lateral pterygoid muscle. The vector-based measurement method demonstrated high intra-observer reliability and may offer a reproducible approach for angular assessment of TMJ structures.

The correlation between the lateral pterygoid muscle attachment type to the disc-condyle complex and temporomandibular joint (TMJ) dysfunction has rarely been discussed and remains unclear. The study aimed to assess the correlation between the number and pattern of LPM attachment and the pathologic findings of the temporomandibular joint based on MR imaging findings. The study population comprised consecutive TMD patients. They were included if they had TMD requiring MRI examination for evaluation of internal derangement. Patients with either TMJ clicking, TMJ locking, restricted movement of the jaw, or pain in the TMJ region were included in the study. Patients with rheumatoid arthritis, condylar hyperplasia, and congenital craniofacial syndrome, and those who had undergone previous TMJ surgery were excluded from this study. Variations of the number of heads and the attachment pattern of the LPM to DCC was evaluated using MRI in the oblique sagittal and coronal images. The variation of the LPM heads and attachment patterns was correlated with pathologic changes of the TMJ. The sample size calculation was performed using G*Power version 3.1.9.2. The significance level was set at 0.05. The data were analysed using Instat statistical software (GraphPad Software, Inc., La Jolla, CA). A total of 255 patients (510 joints) were enrolled in the study. Of these, 52 (104 joints) were male and 203 (406 joints) were female, with ages ranging from 18 to 67 (mean age 32.05). Patients with internal derangement of TMJ were included. According to the data obtained from MRI examinations, LPM attachments to the disc condyle complex were categorized into four different types. The most common variation (type II-B) was shown to be two heads with the upper head attached to the disc and condyle, and the lower to the condyle. There was a statistical correlation between the type of LPM attachment and the pathological changes within the joint regarding disc displacement, osteoarthritis, joint effusion, disc degeneration, and condylar translation ( P  = 0.0003, r = -0.87, P  < 0.0001& r  = 0.29, P  = 0.0002 & r = -0.93, P  = 0.0061 & r = -0.98, and P  = 0.0004, r = -0.54 respectively). The current study shows a statistically significant direct correlation between LPM attachment and TMJ osteoarthritis, while the disc-condyle relationship, joint effusion, disc degeneration, and condylar translation shown significant inverse correlations with LPM attachment patterns.

Background The lateral pterygoid muscle (LPM) plays a critical role in the biomechanics of the temporomandibular joint (TMJ), particularly through its superior lateral pterygoid (SLPM) and inferior lateral pterygoid (ILPM) heads. Recent studies have suggested anatomical variations in LPM morphology and its attachment patterns, potentially contributing to internal derangements and temporomandibular joint disorders (TMDs). This study aimed to evaluate the correlation between LPM attachment types and articular disc displacement using magnetic resonance imaging (MRI). Materials and methods This retrospective study included 266 TMJs from 133 patients (108 female, 25 male) who presented with TMJ-related symptoms. MRI scans were categorized based on LPM attachment types into three groups: Type I (ILPM attached to condyle, SLPM to disc), Type II (ILPM to condyle, SLPM to both disc and condyle), and Type III (ILPM and medial fibers to condyle, SLPM to disc). Disc position was classified as normal, disc displacement with reduction (DDwR), or disc displacement without reduction (DDwoR). Statistical analyses, including Chi-square and Fisher’s Exact Test, were conducted using SPSS v26, with a significance level set at p  < 0.05. Results The distribution of LPM attachment types was as follows: Type I in 27.8% of joints, Type II in 62.4%, and Type III in 9.8%. Regarding disc positions, 36.4% of joints had normal disc position, 35.7% had DDwR, and 27.9% had DDwoR. No statistically significant correlation was found between LPM attachment types and disc displacement (Chi-square = 8.586, p  = 0.072). Conclusion Although anatomical variations in LPM attachments were observed, no significant correlation was identified between these variations and the presence or type of disc displacement. These findings suggest that while LPM morphology is diverse, its role in the pathogenesis of TMD requires further investigation with advanced imaging modalities and functional analysis.

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. 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. 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). 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.

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.

BackgroundIn 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.MethodIt was re-explored an archived computed tomography angiogram of a 60 y.o. female case.ResultsBilateral 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.ConclusionThe 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.

Background/Objectives: Variations in the course of the maxillary artery (MA) relative to the lateral pterygoid muscle (LPM) pose critical challenges in surgical, anesthetic, and interventional procedures involving the infratemporal fossa (ITF). These variations can increase the risk of hemorrhage, nerve injury, or incomplete anesthesia. The present study aimed to elucidate the topographic relationship between the MA and LPM by combining high-resolution radiological imaging with a comprehensive analysis of anatomical literature. Materials and Methods: A retrospective review of 250 brain computed tomography angiographies (CTAs), totaling 500 sides, was conducted to classify the MA course as lateral (superficial), medial (deep), or intramuscular. Additionally, a systematic review and meta-analysis of 32 eligible studies—including 5938 arteries—was performed following PRISMA 2020 and Evidence-Based Anatomy (EBA) guidelines. Study quality and risk of bias were assessed using the Anatomical Quality Assurance (AQUA) tool. Results: In the imaging cohort, the MA coursed lateral to the LPM in 64.2% of sides, medial in 29.6%, and through the muscle fibers in 6.2%. A rare temporalis-traversing variant was identified in 3.0% of cases. Bilateral symmetry was observed in 77.6% of patients. Meta-analytic findings indicated a pooled prevalence of 79.6% for the lateral course, 19.9% for the medial course, and 0.01% for the intramuscular course. Cadaveric studies and Asian populations showed a higher incidence of lateral variants, while imaging-based studies more frequently detected medial and transmuscular paths. Conclusions: While the MA most often follows a lateral course relative to the LPM, clinically significant variation—including medial, intramuscular, and temporalis-traversing routes—exists. These variants complicate access during maxillofacial surgery, TMJ procedures, and regional anesthesia. Findings emphasize the importance of individualized preoperative vascular mapping to improve procedural safety and outcomes in the ITF.

Background and Objectives: The lateral pterygoid muscle (LPM) is typically described as a two-headed muscle within the infratemporal fossa. However, cadaveric and imaging studies have revealed substantial variability in the number of heads, insertion patterns, and relations to neurovascular structures. Materials and Methods: An observational study of 250 brain computed tomography angiographies (CTAs) was performed to assess LPM morphology. Additionally, a systematic review and meta-analysis were conducted in accordance with PRISMA 2020 and Evidence-based Anatomy guidelines. Pooled prevalence estimates were calculated with random-effects models. Results: The current study included 250 CTAs for the original study and 1702 muscles for the meta-analytic evidence. During the original study, the two-headed configuration was most common (74.4%), followed by three-headed (14%), one-headed (10.8%), and four-headed (0.8%) morphologies. Symmetry was observed in 75.2% of patients. Meta-analysis confirmed the predominance of the two-headed type (73.98%, 95% CI: 68.22–79.38), with three-headed (16.82%), one-headed (4.37%), and four-headed (<0.01%) variants occurring less frequently. Subgroup analyses showed no significant differences by study type or sample size, though European populations exhibited a higher prevalence of one-headed forms. Conclusions: The LPM demonstrates considerable morphological variability, extending beyond the traditional two-headed model. Recognition of these variants is essential for understanding temporomandibular joint function, interpreting imaging, and planning surgical or interventional procedures within the infratemporal fossa. Advanced imaging provides a reliable tool for individualized anatomical assessment, supporting safer clinical practice.

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.