Morphology of the temporalis muscle focusing on the tendinous attachment onto the coronoid process

Anatomical consideration of ultrasonography-guided intraoral injection for temporal tendinitis

Temporal tendinitis is characterized by acute inflammation often resulting from mechanical stress, such as repetitive jaw movements associated with jaw opening and closing and teeth clenching. Treatment for temporal tendinitis typically involves the administration of local anesthetic or corticosteroid injections. However, the complex anatomical structure of the coronoid process, to which the temporalis tendon attaches, located deep within the zygomatic arch, poses challenges for accurate injections. In this study, we aimed to establish guidelines for the safe and effective treatment of temporal tendinitis by using intraoral ultrasonography (US) to identify the anatomical structures surrounding the temporalis tendon and coronoid process. US was performed using an intraoral transducer on 58 volunteers without temporomandibular joint disease. The procedure involved placing the transducer below the occlusal plane of the maxillary second molar. Measurements were taken for the horizontal distance from the anterior border of the coronoid process, observed at the midpoint (MP) of the US images, and the depth of the coronoid process and temporalis muscle from the oral mucosa. The anterior border of the coronoid process was visualized on all US images and classified into three observed patterns at the MP: type A (anterior to the MP, 56.2%), type B (at the MP, 16.1%), and type C (posterior to the MP, 27.7%). The temporalis muscle was located at a mean depth of 3.12 ± 0.68 mm from the oral mucosa. The maxillary second molar is an intraoral landmark for visualizing the anterior border of the coronoid process. The new location information obtained using intraoral US could help identify the safest and most effective injection sites for the treatment of temporal tendinitis.

Electromyography Analysis of the Masseter Muscle's Activity in the Management of Oral Submucous Fibrosis

Introduction Oral submucous fibrosis (OSMF) is a persistent, collagen metabolic disorder distinguished by the presence of fibrosis of the connective tissue stroma in the oral mucosa with a higher malignant potential rate for oral cancer. This study aimed to analyze the utility of electromyography (EMG) as the prognostic assessment tool in the management of OSMF with conventional intralesional corticosteroid therapy. Materials and methods This study included 20 OSMF cases of age range 20 to 80 years without systemic comorbidities to assess pre-treatment and post-treatment changes with intralesional corticosteroid therapy as an intervention and to determine if it could be assessed using electromyographic study. Clinical and histopathological grading of OSMF was done. The five clinical parameters were evaluated for measuring treatment prognosis. Among them, mouth opening, tongue protrusion, and burning sensation assessments were quantitative parameters, and palpable fibrotic bands and mucosa colour were qualitative parameters. As OSMF involves changes in muscle plane in moderately advanced and advanced cases, EMG was used as an assessment tool for measuring muscle activity. Among the muscles of mastication, the masseter and temporalis were selected for evaluation. Twenty age and gender-matched healthy controls were required for this study as there are no standardized normal values for amplitude and onset of activity in muscle analysis. The EMG activity of the right and left temporalis and masseter muscles were recorded using surface electrodes and were correlated with five clinical assessment parameters. Results In the right masseter, the rest amplitude of 1.6010 µV of the OSMF was statistically significant (p-value: 0.050) when compared with 4.1275 µV of the control. The clench amplitude of 133.370 µV of the OSMF was statistically significant (p-value: 0.062) when compared with 94.310 µV of the control. In the left masseter, the rest amplitude of 1.6695 µV of the OSMF was statistically significant (p-value 0.066) when compared with 2.5735 µV of the control. In the left masseter, the onset of muscle action of 62.670 ms of the OSMF was statistically significant (p-value: 0.017) when compared with 131.835 ms of the control. The clench amplitude differences in the right masseter of 133.370 µV pre-treatment, and 102.775 µV post-treatment were statistically significant (p-value: 0.007). The clench amplitude in the left masseter of 102.535 µV pre-treatment, and 92.090 µV post-treatment were statistically significant (p-value: 0.036). The correlation was seen between tongue protrusion and rest amplitude in the right masseter in OSMF (r = 0.376, p-value: 0.023). Conclusion There was a correlation between tongue protrusion and rest amplitude in the right masseter muscle in OSMF patients before treatment. In the right and left masseter, during rest, the amplitude of the OSMF group was lesser than that of the control group. During clench, in the right masseter, the amplitude of the OSMF group was higher than that of the control group. During clench in the left masseter, the onset of muscle action was lesser in the OSMF group than in the control group. After treatment, there was a reduction in clench amplitude in OSMF patients from their pretreatment values signifying muscle relaxation and a better onset of muscle action.

Ultrasonographic examination of masticatory muscles in patients with TMJ arthralgia and headache attributed to temporomandibular disorders

This study used ultrasonography to compare the thickness and cross-sectional area of the masticatory muscles in patients with temporomandibular joint arthralgia and investigated the differences according to sex and the co-occurrence of headache attributed to temporomandibular disorders (HATMD). The observational study comprised 100 consecutive patients with TMJ arthralgia (71 females and 29 males; mean age, 40.01 ± 17.67 years) divided into two groups: Group 1, including 86 patients with arthralgia alone (60 females; 41.15 ± 17.65 years); and Group 2, including 14 patients with concurrent arthralgia and HATMD (11 females; 33.00 ± 16.72 years). The diagnosis of TMJ arthralgia was based on the diagnostic criteria for temporomandibular disorders. The parameters of the masticatory muscles examined by ultrasonography were subjected to statistical analysis. The pain area (2.23 ± 1.75 vs. 5.79 ± 2.39, p-value = 0.002) and visual analog scale (VAS) score (3.41 ± 1.82 vs. 5.57 ± 12.14, p-value = 0.002) were significantly higher in Group 2 than in Group 1. Muscle thickness (12.58 ± 4.24 mm) and cross-sectional area (4.46 ± 2.57 cm2) were larger in the masseter muscle than in the other three masticatory muscles (p-value < 0.001). When examining sex-based differences, the thickness and area of the masseter and lower temporalis muscles were significantly larger in males (all p-value < 0.05). The area of the masseter muscle (4.67 ± 2.69 vs. 3.18 ± 0.92, p-value = 0.004) and lower temporalis muscle (3.76 ± 0.95 vs. 3.21 ± 1.02, p-value = 0.049) was significantly smaller in Group 2 than in Group 1. An increase in VAS was significantly negatively correlated with the thickness of the masseter (r =  - 0.268) and lower temporalis (r =  - 0.215), and the cross-sectional area of the masseter (r =  - 0.329) and lower temporalis (r =  - 0.293). The masseter and lower temporalis muscles were significantly thinner in females than in males, and their volumes were smaller in patients with TMJ arthralgia and HATMD than in those with TMJ arthralgia alone. HATMD and decreased masseter and lower temporalis muscle volume were associated with increased pain intensity.

Bichectomy Surgery and EMG Masticatory Muscles Function in Adult Women: A Longitudinal Study

AIM

This longitudinal study aimed to evaluate the electromyographic activity of the masseter and temporal muscles in adult women who underwent buccal fat removal.

MATERIALS AND METHODS

The sample consisted of 20 healthy adult women with no temporomandibular dysfunction and normal occlusion, who were assessed before, 30, and 60 days after the surgery. The electromyographic signal of the masseter and temporal muscles was captured through mandibular tasks including rest, protrusion, right and left laterality, and maximum voluntary contraction with and without parafilm. The results obtained were tabulated and the Shapiro-Wilk normality test was performed, which indicated a normal distribution. Statistical analysis was performed using the repeated measures test (p < 0.05).

RESULTS

Significant differences were observed between time periods in maximum voluntary contraction for the left masseter muscle (p = 0.006) and in maximum voluntary contraction with parafilm for the right temporal (p = 0.03) and left temporal (p = 0.03) muscles.

CONCLUSION

Bichectomy surgery did not modify the electromyographic activity of the masseter and temporal muscles during the rest task but may have influenced variations in the electromyographic signal during different mandibular tasks after 60 days of surgery, suggesting compensatory adaptations and functional recovery.

CLINICAL SIGNIFICANCE

Understanding the impact of buccal fat removal surgery on the stomatognathic system function provides insights into postoperative functional recovery and potential compensatory adaptations, guiding clinical management and rehabilitation strategies for patients undergoing such procedures. How to cite this article: Cardoso AHDLS, Palinkas M, Bettiol NB, et al. Bichectomy Surgery and EMG Masticatory Muscles Function in Adult Women: A Longitudinal Study. J Contemp Dent Pract 2024;25(3):207-212.

Two-Stage Anatomic Myocutaneous Flap Dissection in Cranioplasty: Technical Nuances and Single-Surgeon Experience

BACKGROUND AND OBJECTIVES

Temporalis muscle management remains one of the most challenging aspects of cranioplasty, which accounts for considerable rates of dissection-related complications. Since 2019, the senior author has developed and consistently used a methodical, two-stage anatomic dissection technique to separate the scalp and temporalis muscle from the underlying brain. This technique is believed to facilitate dissection and minimize the risk of brain injury, while optimizing cosmetic outcomes.

METHODS

All patients who underwent cranioplasty between January 2019 and February 2023 were identified from a prospectively maintained database. Charts were retrospectively reviewed. Demographic, clinical, and procedural data were extracted and analyzed.

RESULTS

Twenty-nine patients, 20 men and 9 women with a median age of 37 years (range 17-72), were identified. Indications for craniectomy were traumatic brain injury in 18 (62.1%), hemorrhagic stroke in five (17.2%), ischemic stroke in four (13.8%), and aneurysmal subarachnoid hemorrhage in two (6.9%). Median precranioplasty modified Rankin Scale and Glasgow Coma Scale scores were 5 (range in series: 0-5) and 14 (range in series: 3-15), respectively. The median time to cranioplasty was 131 days (32-1717). Cranioplasty was technically successful in all patients, with a median operative time of 106 minutes (62-182). There were no intraoperative complications. Postoperative complications occurred in three patients (10.3%): hemorrhagic brain contusion (n = 1), meningitis (n = 1), and seizure (n = 1). Of those, one patient (3.4%) died 2 weeks after surgery from suspected pulmonary embolism. After a median follow-up of 4 months (1-44), all 28 survivors have either remained clinically stable or exhibited neurological improvement. Cosmetic results were good or excellent in 27 (96.4%) and fair in one (3.6%).

CONCLUSION

Two-stage anatomic dissection of the scalp and temporalis muscle during cranioplasty can maximize surgical efficiency and result in excellent outcomes. Cranioplasty should be considered a low-risk, low-complexity neurosurgical procedure. Safe and efficient management of the temporalis muscle is key.

Temporalis Muscle Transposition in Irreversible Facial Nerve Palsy:‎ A Vestibular Approach

Background The facial nerve plays a crucial role in innervating the motor supply of facial muscles, enabling essential facial expressions that facilitate human communication. Defects or damages to this nerve can have significant consequences, leading to functional, emotional, and social difficulties caused by the immobility of facial muscles. Patients suffering from irreversible facial nerve palsy often experience functional symptoms such as eyelid closure defects, mouth deviation, and limited movement. Methods This study aims to address these challenges and offer potential solutions for patients with irreversible facial nerve palsy. In this study, 18 patients (three males and 15 females) underwent temporalis transfer with an intraoral approach in the cranio-orbito-palpebral unity. Preoperative facial reanimation planning involved evaluating the smile's appearance on the unaffected side. Photographs were captured in various positions, and facial expressions were examined. Following this, botulinum toxin was injected into the normal side of the face seven days before the procedure to address the hyperactive condition of the mimic muscles. Results Temporalis transfer with an intraoral approach for oral commissure reanimation in the context of irreversible facial nerve palsy was performed. The surgical procedure combined coronal and orbital approaches and achieved the desired outcomes. Postoperative complications observed included hematomas and ossification. Functional outcomes, assessed using the House-Brackmann grading system, indicated a mean improvement of 2.5, signifying moderate dysfunction with normal tone and facial symmetry. Conclusion This intervention represents an alternative approach to actual techniques of facial palsy reanimation, especially in selected patients who can benefit from the absence of visible scars, such as young patients and those prone to hypertrophic and keloid scarring, as well as patients with non-prominent nasolabial folds.