Comparison of clinical marking and ultrasound-guided injection of Botulinum type A toxin into the masseter muscles for treating bruxism and its cosmetic effects

Ultrasound-Guided Botulinum Toxin-A Injections into the Masseter Muscle for Both Medical and Aesthetic Purposes

With the increasing use of Botulinum toxin type A (BoNT-A) injections in the masseter muscles for both medical and aesthetic purposes, there is a constant need to continually enhance the efficacy of these treatments and reduce the risk of potential adverse events. This review provides an in-depth analysis of the masseter muscle's anatomical structure and essential landmarks and emphasizes the advantages of ultrasound (US) guidance in improving the precision of BoNT-A injections compared to conventional blind methods. The review is supplemented with comprehensive figures, including graphics, clinical images, and ultrasound visuals, to support the discussion. Potential complications such as paradoxical bulging, inadvertent injections into the risorius muscle or parotid gland, facial paralysis, and the risk of bone resorption are examined. Future research should aim at refining injection techniques and assessing the long-term effects of repeated treatments to ensure optimal patient care and safety.

Botulinum toxin for bruxism treatment: a nationwide study among oral and maxillofacial surgeons in Germany

INTRODUCTION

This study aimed to evaluate the use of botulinum toxin (BTX) for the treatment of bruxism in oral and maxillofacial surgery in Germany.

MATERIAL AND METHODS

A dynamic online questionnaire comprising 7 to 25 questions was formulated to gather general and specific information regarding using BTX to treat bruxism. The questionnaire underwent internal and external assessments for validation. Subsequently, it was distributed to 906 oral and maxillofacial surgeons (OMFS) affiliated with the German Association for Oral and Maxillofacial Surgery (DGMKG). Weekly reminders were dispatched over four weeks to enhance response rates. Participation in the study was voluntary and anonymized. Descriptive methods were employed for data analysis.

RESULTS

107 OMFS participated in the study, yielding a response rate of 11.81%. On average, 17 patients with bruxism were per month, with 4 of these patients receiving BTX therapy. BTX administration was frequently accompanied by splints and physiotherapy (35.51% of participants). Botox® (Allergan) was the preferred BTX preparation, utilized by 40.79% and reconstituted with saline by 92.11% of participants. The masseter muscles were primarily targeted for BTX treatment (67.57% of participants), averaging 29 BTX (Allergan-) units per side. Injection points for each masseter muscle typically amounted to six per side, preferred by 30.67% of participants. Follow-up assessments post-BTX treatment were conducted regularly, predominantly after four weeks, by 36% of participants. In 8% of cases, additional BTX injections were necessary due to inadequate outcomes. Side effects were reported in 4% of cases, commonly manifesting as a non-disturbing reduction in bite force. Most participating OMFS (61.84%) using BTX for bruxism therapy regarded bruxism treatment with BTX as evidence-based. Notably, 97.37% of respondents expressed their willingness to recommend BTX-based bruxism treatment to their colleagues. Overall, the efficacy of BTX therapy for bruxism was rated as good (53.95%) and very good (40.79%).

CONCLUSION

The use of BTX for the management of bruxism among OMFS in Germany has demonstrated efficacy. Substantial variances in certain facets of bruxism treatment employing BTX have been observed.

CLINICAL RELEVANCE

Additional research endeavors are warranted to comprehensively investigate distinct elements of BTX therapy for bruxism, including the optimal dosage of BTX units and the precise localization of injection sites across various muscles.

Functional and esthetic effects of botulinum toxin injection into the masseter muscles: evaluation of 80 patients from a dermatological perspective

BACKGROUND

Masseter muscle hypertrophy is characterized by a symmetrical or asymmetrical increase in muscle volume. Although it can be asymptomatic, it may be associated with bruxism. Therefore, patients may seek intervention for esthetic and/or functional concerns. This study aimed to establish patient characteristics, purpose of undergoing botulinum toxin injection into the masseter muscles, efficacy, and side effects of the procedure at a dermatology clinic.

METHODS

A retrospective chart review was carried out over a period of one year from January 2022 to January 2023 for the patients who underwent botulinum toxin injection into the masseter muscles. The general characteristics of patients, the purpose of botulinum toxin treatment, relief levels regarding bruxism according to the Visual Analog Scale (VAS), side effects, and complications were recorded.

RESULTS

The study group comprised 74 female and 6 male patients with a mean age of 31.20 ± 6.71 years. Eighteen (22.5%) patients were treated only for narrowing the lower face contour, 28 (35%) patients were treated only for the relief of bruxism, and 34 (42.5%) patients were treated for both indications. Fifteen (18.8%) patients experienced 16 treatment-related side effects, including two (2.5%) with smile asymmetry and two (2.5%) with paradoxical bulging.

CONCLUSIONS

Botulinum toxin injection into the masseter muscles with the intention of lower face contouring and/or relieving bruxism offers a minimally invasive, safe, and effective treatment option. Although it has a favorable safety profile, the risks of significant side effects or complications remain.

Ultrasound-Guided Injections for Treatment of Facial Paralysis Sequelae: A Randomized Study on Body Donors

BACKGROUND

Botulinum toxin injection is the accepted standard treatment for synkinesis and gustatory hyperlacrimation in patients with facial paralysis. However, poor injection accuracy can result in inconsistent treatment outcomes, variable treatment durations, and complications. Ultrasound guidance should increase injection accuracy in the facial region; however, this has not been proven.

METHODS

Twenty-six hemifaces of nonembalmed cadavers were studied in a randomized split-face manner. Ink was injected with ultrasound or landmark guidance into the lacrimal gland and three common synkinetic muscles: the orbicularis oculi, depressor anguli oris, and mentalis. Injection accuracy was evaluated using several measures.

RESULTS

Using ultrasound guidance, most ink (>50%) was found inside the correct target in 88% of cases, compared with 50% using landmark guidance ( P < 0.001). This was most pronounced in the lacrimal gland (62% versus 8%), depressor anguli oris (100% versus 46%), and mentalis (100% versus 54%) ( P < 0.05). All ink was found inside the correct target (no ink outside) in 65% using ultrasound guidance versus 29% without ( P < 0.001). Injection accuracy (any ink in target) was 100% when using ultrasound guidance versus 83% without ( P < 0.01). Twenty-three percent of the landmark-guided depressor anguli oris injections stained the facial artery ( P = 0.22).

CONCLUSIONS

Ultrasound guidance significantly increased injection accuracy and reduced the amount of ink lost in the surrounding tissue compared with landmark guidance. Clinical trials are needed to explore the effects of ultrasound guidance on treatment outcome, duration, and complications in patients with facial paralysis.

Key Points to Select a Device for Dermatologic Ultrasound

What points to consider when selecting a device for practicing dermatologic ultrasound is an excellent question. After we met the requisites published in the guidelines for practicing dermatologic ultrasound, it is necessary to consider the main objective of the use because it is not the same to be focused mostly on the avoidance of the puncture of important facial vessels such as the case of injectors of cosmetic fillers in comparison to the use of operators that need to deal with the diagnosis and monitoring of a wide range of dermatologic pathologies. Currently, a broad variety of ultrasound devices meets the minimum requirements for practicing these examinations in the market. Thus, small, portable, and high-end devices may present advantages and limitations that must be balanced according to the primary purposes and the budget. Moreover, the shape and footprint of the probes can make difficult or facilitate a dermatologic procedure. Other points to consider are the type of storage and the need for technical service. In summary, there are key points that we need to consider when we select a dermatologic ultrasound device in dermatology or aesthetics.

The growing importance of ultrasonography in cosmetic dermatology: An update after the 23rd IMCAS Annual World Congress (2022)

BACKGROUND

Ultrasound (US) has been used for many years in the field of medicine. Many specialties have embraced US as a quick, painless, and relatively inexpensive tool to assist the clinician in determining anatomy, pathology, and aid in diagnostic or therapeutic procedures. US allows for precise mapping of cutaneous and subcutaneous structures in the face, in particular vascular structures. The use of US leads to reduced chances of complications and clinical failures, rendering more safety and high quality.

METHODS

US is considered the first-imaging technique for dealing with fillers and managing their potential complications. US can be deployed for vascular mapping, safe placement of fillers, and directed low-dose hyaluronidase reversal of vascular adverse events. It is a noninvasive imaging modality that provides a good definition for studying the skin, deeper layers, and blood flow in real time. In other words, we go from static to dynamic anatomy. In addition, US can guide with the application of botulinum toxin, in order to define the muscular planes. US may contribute to a more personalized procedure, better cosmetic results, and help to avoid complications. In general, physicians tend to use it for prevention. Last, for research purposes, US examination provides valuable information on the behavior, longevity, and interaction of the filler within the tissues.

CONCLUSION

This new approach for US-guided treatments is a very practical and an effective method in cosmetic dermatology. As doctors, we owe it to our patients to do our best to prevent any harm. We feel that in near future, US will be an essential diagnostic tool in any dermatology or cosmetic doctor's office to both ensure safety and provide legal protection for the professional.

The Evaluation of the Relationship between Changes in Masseter Muscle Thickness and Tooth Clenching Habits of Bruxism Patients Treated with Botulinum Toxin A

Background

Bruxism is defined as recurrent masticatory muscle activity. Although there is not an agreed treatment method for bruxism, the application of botulinum toxin A (BT-A) has become a reliable lately. This study aimed to evaluate the correlation between the changes in masseter muscle thickness and clenching habits in bruxism patients treated with BT-A.

Methods

Twenty-five patients, 23 females and 2 males, diagnosed with possible sleep bruxism were included in the study. The Fonseca Anamnestic Index was applied to the patients to determine their clenching habits and depression levels both before the treatment, and 6 months after it. The masseter muscle thickness was measured using ultrasonography before the treatment and 3 months and 6 months after the treatment. All the patients were injected with a total of 50 U of BT-A, 25 U to each masseter.

Results

A statistically significant decrease in masseter muscle thickness was observed in the ultrasonography 3 and 6 months after the BT-A treatment. There was a statistically significant decrease in the Fonseca scores, in which the teeth clenching habits of the patients were evaluated 6 months after the treatment. Although there was a decrease in the depression levels of the patients 6 months after the treatment, this difference was not statistically significant.

Conclusion

When the results of this study were evaluated, it was seen that the BT-A injections are an effective, safe, and side effect-free method in the treatment of bruxism and masseter hypertrophy.

Botulinum Toxin Injection for Masseteric Hypertrophy Using 6 Point Injection Technique - A Case Report. Proposal of a Clinical Technique to Quantify Prognosis

Introduction

Masseter hypertrophy presents as unilateral or bilateral swellings over the ramus and angle of the mandible. It is caused by malocclusion, clenching, TMJ disorders, etc and alters facial symmetry, leading to discomfort and negative cosmetic impact in many patients, making this a popular request for aesthetic and functional correction.

Materials and Methods

This case report involves injecting Botulinum toxin into 6 equidistant bulging points on the masseter. Standardized photography and clinical parameters were used to assess facial contour and masseter muscle thickness at baseline and successive follow ups.

Results and Discussion

Significant masseteric bulk reduction was observed in subsequent follow ups.

Conclusion

The 6-point technique was found to be an effective treatment modality for Botox injection in masseteric hypertrophy. The clinical method to quantify prognosis was easy and economical.

Ultrasonographic observation of the masseter muscle after injection of different botulinum toxin type A

BACKGROUND

Botulinum toxin type A (BoNT-A) injection is a popular cosmetic procedure in East Asian countries, and there are multiple types of toxins on the market. Whether different toxin types induce different changes in the masseter has not been studied.

OBJECTIVE

We aimed to investigate and compare the changes induced by injection of different types of BoNT-A in the masseter.

METHODS

Upon retrospective review of clinical records and routine ultrasound examination results of patients who underwent BoNT-A injection, four groups were set for comparison: unapproved toxin, OnabotulinumtoxinA, LanbotulinumtoxinA, and non-injected. Clinical records and ultrasound images were collected. Ultrasound images were taken in both horizontal and coronal planes. Elasticity of the masseter muscle was also investigated by measuring the surface wave speed.

RESULTS

A total of 24 patients were included (six patients per group). All patients were young females. For the non-injected group, the deep inferior tendon was clear and the muscle bundles were arranged, with little fibrous content. Patients who received unapproved toxin injection showed highly disarranged muscle and fiber bundles, with much fiber content present. The changes in OnabotulinumtoxinA and LanbotulinumtoxinA groups were in between those in the non-injected and unapproved toxin groups. Muscle rigidity was the highest in the unapproved toxin group, and generally higher in injected groups compared with the non-injected group.

CONCLUSION

Different types of BoNT-A may induce different changes in the masseter.

Botulinum toxin A in dentistry and orofacial surgery: an evidence-based review - part 1: therapeutic applications

Objective An evidence-based review on the safety and efficacy of botulinum toxin type-A (BoNTA) in orofacial conditions, focusing on the therapeutic applications and role of BoNTA as an adjuvant treatment.Data source and selection Data was collected using PubMed (Medline), Cochrane Library of Systematic Reviews and Cochrane Central Register of Controlled Trials electronic databases. Having satisfied the search parameters, 32 studies for therapeutic applications and 26 for BoNTA as an adjunctive treatment were included. The quality of relevant studies was assessed using the Best Evidence Topics (BETs) Critical Appraisal Tool.Data extraction The highest level of evidence (LOE) behind BoNTA safety and efficacy was for wound healing and scar management in the orofacial surgery context, where BoNTA was presented as an adjunctive modality. Level-I evidence was controversial for temporomandibular disorders and bruxism. However, it showed promising results for painful temporomandibular disorders of myogenic origin refractory to conservative therapies, and to decrease muscle contraction intensity in sleeping bruxism. There was only one level-II study for persistent recurrent aphthous stomatitis. Data showed limited level-III evidence for orofacial pain conditions (temporomandibular joint recurrent dislocation and pain, burning mouth syndrome or atypical odontalgia), oral cancer complications, or as an adjuvant to maxillofacial and orthognathic surgeries. Benefits of BoNTA in prosthodontics had weak level-IV evidence. No evidence was found among the periodontology field.Conclusion There is growing evidence to support the safety and efficacy of BoNTA in the investigated orofacial pathological conditions, with high levels of satisfaction from the patient and clinician perspective. However, there are some inconsistencies and limited high-quality evidence available. Well-designed controlled clinical trials are necessary to evaluate long-term safety, efficacy and cost-effectiveness before BoNTA is widely adopted with irrefutable evidence-based clinical guidelines.

Efficacy of botulinum toxin in masseter muscle hypertrophy for lower face contouring

BACKGROUND

Masseter muscle hypertrophy (MMH) usually presents with cosmetic concerns as it may lead to widening of the lower face. Apart from the traditional surgical approaches, botulinum toxin type A (BTA) injection is a non-invasive treatment option available. There are no standard guidelines for this procedure.

OBJECTIVES

To study the efficacy of botulinumtoxin A in MMH for lower face contouring.

METHODOLOGY

The Cochrane Library, PubMed/MEDLINE, Google-scholar, Science-Direct database, and ResearchGate from inception until September 2021 were searched using the keywords "botulinumtoxin type A," "masseter muscle hypertrophy," "lower face contouring," and "masseter botox." All available retrospective and prospective studies, case-series, case-reports, and expert reviews were included with an emphasis on efficacy of BTA in MMH and units injected into the muscle, points of placement, adverse events, and the duration of its effect. Reference lists of the resultant articles, as well as relevant reviews, were also searched.

RESULT

40 articles were shortlisted for the review, of which 14 studies with sample-size ≥10 in accordance with the study requirements were summarized in a tabular form for analysis and easy comparison and reference.

CONCLUSION

BTA injection is a non-invasive, safe, and effective treatment for MMH. The optimum number of BTA units could not be ascertained due to wide variability in the studies as well as ethnicity of patients and extent or some measurement of MMH. The points of placement of injection should be well within the boundaries of the masseter muscle. The maximum effect of BTA after a single injection session is usually seen in ~3 months, and the duration may last for 6-12 months. Multiple injection sessions may be required to maintain a long-term effect. Injection technique and total number of injection units of neuromodulator must be individualized for each patient.

Ultrasound-Guided OnabotulinumtoxinA Injections to Treat Oromandibular Dystonia in Cerebral Palsy

Cerebral palsy (CP) is a group of non-progressive disorders of motor function in children resulting from an injury to an immature brain. In addition to abnormal limb and trunk movement, individuals with CP can experience involuntary muscle contractions of the lower facial muscle groups, causing oromandibular dystonia (OMD). Contraction of the lateral pterygoids and submandibular muscles depresses the mandible. OMD involving the lateral pterygoids can therefore lead to involuntary jaw opening posture, affecting the ability to feed and speak effectively. We present a case series of five patients with CP and OMD that received novel ultrasound-guided onabotulinumtoxinA to the lateral pterygoid muscles. Our goal was to determine if chemodenervation would improve the mouth-closing ability, thus in turn improving the ability to swallow, chew, manage secretions, and communicate. We describe this unique injection method and report a subjective improvement in eating abilities and communication, in addition to a positive upward trend in most patients’ weights, with no significant adverse side effects.

The "Visible" Muscles on Ultrasound Imaging Make Botulinum Toxin Injection More Precise: A Systematic Review

BACKGROUND

Botulinum toxin (BoNT) injection is the most commonly performed procedure in cosmetic surgery. However, blind injection is unable to take individual anatomical variations into consideration, which is the main contributing factor to complications. Ultrasound (US) imaging was introduced to reduce complications and improve effects. This article will review uses of US in aesthetic BoNT injection.

METHOD

A systematic electronic search was performed using the PubMed, MEDLINE, Web of science. Search terms were set to focus on aesthetic BoNT injection. Two independent reviewers subsequently reviewed the resultant articles based on strict inclusion and exclusion criteria. Selected manuscripts were analysed and grouped by procedure categories. Clinical cases were all performed by one plastic surgeon in our department.

RESULTS

The search finally retained 24 articles. Five procedural categories were identified, including masseter (n = 16), frontalis (n = 2), glabella complex (n = 2), trapezius (n=1), and gastrocnemius (n = 3). US imaging is practical and instructive for pre-operative assessments as in needle-type selection, injection point localization and depth setting, as well as post-operative follow-ups regarding injection feedback (for instance, the extent of muscle volume decreases). What's more, ultrasound-guided injection makes needle trajectory visualized so as for the needle to reach the target muscle in avoidance of potential damage to neurovascular bundle, gland or adjacent muscle.

CONCLUSION

Muscles, such as masseter, frontalis, glabella complex, trapezius and gastrocnemius, and their adjacent structures can be well visualized using US, and as such, US can be a useful tool for a variety of pre-operative, intra-operative and post-operative procedures.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Effects of ultrasound-assisted botulinum neurotoxin-A injection in patients with bruxism and masseter hypertrophy

Objectives

This study aims to explore effects of ultrasound-assisted injection of the botulinum neurotoxin-A (BoNT-A) on muscle thickness (MT) in patients with masseter hypertrophy.

Patients and methods

Between December 2018 and December 2019, a total of 20 patients (3 males, 17 females; mean age: 28±6.9 years; range, 18 to 42 years) with bruxism who underwent BoNT-A injections were reviewed retrospectively. The patients were treated using individualized injection dosages and sites. Assessment methods included length between the tragus and the angle of the mouth, maximal bite force, and MT of the masseter muscle. Follow-up data were collected from the hospital electronic database.

Results

There were 26 masseter muscles with masseter hypertrophy in 20 patients. There was a significant difference in ultrasonographic measurements of the relaxed and contracted masseter muscles between the baseline and two weeks, one month and three months after the treatment (p<0.05). In the ultrasonographic measurement of the relaxed masseter muscle, post-treatment third month values significantly differed from the second week values. The differences in the measurement of the line between the tragus and the angle of the mouth between the baseline and two weeks, one month and three months after the treatment were statistically significant (p<0.05). In the maximal bite force measurements, no significant difference was observed between the baseline and post-intervention measurements (p>0.05).

Conclusion

The MT decreases after a single dose of BoNT-A injection in patients with masseter muscle hypertrophy and ultrasonography is a convenient imaging modality for BoNT-A injection to the masseter.

Botulinum toxin type A injections for masticatory muscles hypertrophy: A systematic review

The aim of this study is to compare the efficacy of single-point injection of botulinum toxin A versus multi-point operative protocols found in the literature in reducing hypertrophy in patients with masticatory muscle hypertrophy. A systematic review was performed in accordance with the Park et al., 2018 guidelines, selecting articles from PubMed, Google Scholar, Web of Science and Ovid databases up to July 8, 2020.28 studies met the eligibility criteria. 748 patients were treated for masseter hypertrophy (MH) and 4 patients for temporal muscle hypertrophy. As for MH: in 45.2% of cases 3 injection sites (IS) were used, in 18.8% 1 IS, in 16.2% 2 IS, in 13% 5 IS, in 4.1% 6 IS, 2.7% 4 IS. At three months, the mean reduction in masseter muscle thickness is 26-31% when 1 IS was used, 28% in 2 IS, 12-27% in 3 IS and 22-30% in 6 IS. Heterogeneity of results, high bias level and selective reports led to a difficult efficacy comparison of the injection techniques described. Data suggest that the lowest number of IS possible should be used until stronger evidences are presented. Homogeneity in pre- and post-operative protocols is needed to establish a reliable setting for the condition under study.

European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) Position Statement on Dermatologic Ultrasound

Dermatologic ultrasound is a recent application of ultrasound for the evaluation of healthy skin and appendages and their diseases. Although the scientific literature regarding this application is still not sufficient for evidence-based guidelines, general recommendations issued by scientific societies are necessary. The EFSUMB (European Federation of Societies for Ultrasound in Medicine and Biology) steering committee for dermatologic ultrasound has developed a series of consensus position statements regarding the main fields of dermatologic ultrasound (technical requirement, normal skin and appendages, inflammatory skin diseases, tumoral skin diseases, aesthetic dermatology and practice-training requirements). This document is the foundation for future evidence-based recommendations and guidelines for dermatologic ultrasound practice.

High-frequency ultrasound in the 21st century

The beginnings of skin ultrasound date back to about 50 years ago. However, the dynamic progress of skin ultrasound took place in the last twenty years, when the unprecedented development of computer technologies occurred, which resulted in the popularization of and easier access to modern ultrasound equipment. Skin tests can be performed with both classic scanners equipped with broadband transducers with a minimum frequency of 15 MHz, and specially dedicated skin systems with high-frequency scanners, which are equipped with mechanical transducers with a frequency of 20 MHz to up to 100 MHz. Owing to technologically advanced machines, ultrasonography has proved to be useful in many areas. The aim of this study was to present the current knowledge and possibilities of skin imaging using high-frequency ultrasonography. Te paper discusses technical aspects, types of devices available on the market, as well as methods for the analysis of ultrasound skin images and parameters useful in their interpretation. We also present current applications of skin ultrasound, with particular emphasis on dermatology and aesthetic medicine. In the field of dermatology, we discussed imaging of focal lesions as well as an assessment of pathologically changed skin and treatment monitoring. We also focused on the use of high-frequency ultrasonography in aesthetic medicine and cosmetology. The popularity of this method is constantly growing in these fields, and ultrasound is now used in everyday practice to assess the skin, plan and monitor procedures, as well as to treat potential complications. High-frequency ultrasonography is a highly effective method for skin evaluation, although still underappreciated in may fields. Further research is needed to standardize this modality, as well as to implement training for operators, and to popularize this imaging technique.

Ultrasound Imaging of Injections in Masseter Muscle without Contrast Agent Using Strain Elastography and a Novel B-Mode Spatiotemporal Filter

Botulinum toxin type A (BTX-A) injections in masseter muscle can alleviate muscle tightness and aching pain caused by idiopathic masticatory myalgia, a subform of the myofascial pain syndrome. Yet the injection procedure (number, amount) is currently empirical. In this ex vivo study, we determined the feasibility of using contrast-free ultrasound imaging to visualize the short-term injectate propagation. Ultrasound annotations of BTX-A injectate spread in N = 12 porcine masseter muscles were compared with the histopathology of the excised masseter. BTX-A presence was automatically detected in the ultrasound cine by: compensating tissue motion and deformation during injection with a novel spatiotemporal filtering (SF) algorithm, and by imaging tissue swelling strains with strain elastography (SE). BTX-A injectate introduced 6.5% (standard deviation = 5.0%) echogenicity contrast and 13.9% (standard deviation = 3.7%) tissue swelling strain. Muscle fasciae were a border for BTX-A distribution. The SF algorithm achieved significantly higher noise rejection (contrast-to-noise ratio = 4.63) than SE (2.56, p = 0.01), and state-of-the-art 2-D digital image correlation (1.81, p < 0.001) and direct image subtraction (1.29, p < 0.001) methods. Histopathology agreed well with ultrasound (Dice coefficient = 0.48), with deviations mainly explained by the three-dimensional inhomogeneous distribution of BTX-A. Preliminary in vivo patient results indicated that SF and SE discard artifactual BTX-A detection outside the injection region. The proposed methods contribute to objectivize ultrasound-guided injections, with additional applications, for instance, to monitor injectate spread of local anesthetics.

Comparison between Conventional Blind Injections and Ultrasound-Guided Injections of Botulinum Toxin Type A into the Masseter: A Clinical Trial

The aim of the study was to propose a more efficient and safer botulinum toxin type A (BoNT-A) injection method for the masseter by comparing the conventional blind injection and a novel ultrasonography (US)-guided injection technique in a clinical trial. The 40 masseters from 20 healthy young Korean volunteers (10 males and 10 females with a mean age of 25.6 years) were included in this prospective clinical trial. The BoNT-A (24 U) was injected into the masseter of each volunteer using the conventional blind and US-guided injection techniques on the left and right sides, respectively, and analyzed by US and three-dimensional (3D) facial scanning. One case of PMB (paradoxical masseteric bulging) was observed on the side where a conventional blind injection was performed, which disappeared after the compensational injection. The reduction in the thickness of the masseter in the resting state differed significantly at 1 month after the injection between the conventional blind injection group and the US-guided injection group by 12.38 ± 7.59% and 17.98 ± 9.65%, respectively (t(19) = 3.059, p = 0.007). The reduction in the facial contour also differed significantly at 1 month after the injection between the conventional blind injection group and the US-guided injection group by 1.95 ± 0.74 mm and 2.22 ± 0.84 mm, respectively (t(19) = 2.908, p = 0.009). The results of the study showed that the US-guided injection method that considers the deep inferior tendon by visualizing the masseter can prevent the PMB that can occur during a blind injection, and is also more effective.

Muscular Contribution to Adolescent Idiopathic Scoliosis from the Perspective of Stem Cell-Based Regenerative Medicine

Adolescent idiopathic scoliosis (AIS) is a relatively frequent disease within a range 0.5%-5.0% of population, with higher frequency in females. While a resultant spinal deformity is usually medically benign condition, it produces far going psychosocial consequences, which warrant attention. The etiology of AIS is unknown and current therapeutic approaches are symptomatic only, and frequently inconvenient or invasive. Muscular contribution to AIS is widely recognized, although it did not translate to clinical routine as yet. Muscle asymmetry has been documented by pathological examinations as well as systemic muscle disorders frequently leading to scoliosis. It has been also reported numerous genetic, metabolic and radiological alterations in patients with AIS, which are linked to muscular and neuromuscular aspects. Therefore, muscles might be considered an attractive and still insufficiently exploited therapeutic target for AIS. Stem cell-based regenerative medicine is rapidly gaining momentum based on the tremendous progress in understanding of developmental biology. It comes also with a toolbox of various stem cells such as satellite cells or mesenchymal stem cells, which could be transplanted; also, the knowledge acquired in research on regenerative medicine can be applied to manipulation of endogenous stem cells to obtain desired therapeutic goals. Importantly, paravertebral muscles are located relatively superficially; therefore, they can be an easy target for minimally invasive approaches to treatment of AIS. It comes in pair with a fast progress in image guidance, which allows for precise delivery of therapeutic agents, including stem cells to various organs such as brain, muscles, and others. Summing up, it seems that there is a link between AIS, muscles, and stem cells, which might be worth of further investigations with a long-term goal of setting foundations for eventual bench-to-bedside translation.

Ultrasonographic and Three-Dimensional Analyses at the Glabella and Radix of the Nose for Botulinum Neurotoxin Injection Procedures into the Procerus Muscle

Botulinum neurotoxin (BoNT) injections are widely used for facial rejuvenation procedures, and the procerus muscle is a major target in cases of glabellar transverse lines or rhytids. Although there have been many cadaveric studies of the procerus, its depth and thickness have not been investigated thoroughly. The aim of this study was to measure the depth and thickness of the procerus and identify the location of the intercanthal vein using ultrasonographic (US) imaging and the three-dimensional scanning method, which is needed to know to avoid side effects during BoNT injections. The morphology of the procerus was classified into two types based on the US images obtained at the glabella. The procerus was located deeper below the skin surface at the glabella than the sellion (3.8 ± 0.7 mm versus 2.7 ± 0.6 mm). The width of the procerus in US images increased from the sellion (10.9 ± 0.2 mm) to the glabella (14.5 ± 4.6 mm), whereas its thickness decreased (from 1.6 ± 0.6 mm to 1.1 ± 0.5 mm). The intercanthal vein was located 5.1 ± 4.0 mm superior to the sellion and 3.0 ± 0.6 mm below the skin’s surface. The present findings provide anatomical knowledge as well as the reference location information for use when injecting BoNT into the procerus.

Ultrasonography of the internal architecture of the superficial part of the masseter muscle in vivo

It is unclear whether the deep inferior tendon (DIT) is equally present in vivo, and little anatomical information is available regarding the existence and morphology of the DIT in healthy young subjects. The aim of this study was to characterize the DIT of the masseter muscle in healthy young subjects using ultrasonography and to compare the morphology of this tendon with previously reported data for healthy young subjects in order to provide the most-effective injection methods for botulinum neurotoxin treatments of masseteric hypertrophy. This study investigated two fresh cadavers and 30 healthy subjects. Ultrasonography scanning in both longitudinal and transverse directions was applied to the masseter muscle. The DIT within the superficial part of the masseter was observed in both the fresh cadavers and the living subjects. The posterior region of the masseter muscle was compartmentalized (entirely covered) by the DIT in 26.7% of the specimens. The superficial part of the masseter muscle was divided by the DIT transversely and longitudinally into the superficial and deep muscle bellies in 35% and 38.3% of the specimens, respectively. The present findings suggest applying a DIT-based injection technique under guidance by ultrasonography prior to treating masseteric hypertrophy. Clin. Anat. 32:446-452, 2019. © 2019 Wiley Periodicals, Inc.

Botulinum Toxin A for Spastic Trismus Due to Brain Stem Encephalitis in a Pediatric Intensive Care Setting: A Unique Case Report

Injection of botulinum toxin A to masseter and temporalis muscles improved mouth opening and facilitated suction and oral care in a child with spastic trismus. This is the first such report in a 3.5-year-old child on mechanical ventilator in pediatric intensive care unit setting.

Current applications of high-frequency ultrasonography in dermatology

The era of ultrasounds in dermatology started in 1979, when pioneering use of 15 MHz by Alexander and Miller in measuring the skin thickness was introduced. Since then, some new applications of high-frequency ultrasonography (HF-USG) have emerged providing the clinicians with an extra hand in their everyday practice. The main advantages of HF-USG include the possibility of real-time imaging, measurements of morphological and physiological aspects of the skin, safety associated with the use of non-ionizing media as well as the lack of contraindications to its performance. Currently the main clinical use of HF-USG in dermatology regards preoperative assessment of the depth of invasion in melanomas and basal cell carcinomas. The ultrasound image analysis allows noninvasive follow-up of inflammatory skin diseases, like atopic dermatitis, psoriasis and may be used for monitoring effectiveness of therapy in skin lymphomas and sclerotic skin diseases.

The Anatomical Basis of Paradoxical Masseteric Bulging after Botulinum Neurotoxin Type A Injection

The aim of this study was to determine the detailed anatomical structures of the superficial part of the masseter and to elucidate the boundaries and locations of the deep tendon structure within the superficial part of the masseter. Forty-four hemifaces from Korean and Thai embalmed cadavers were used in this study. The deep tendon structure was located deep in the lower third of the superficial part of the masseter. It was observed in all specimens and was designated as a deep inferior tendon (DIT). The relationship between the masseter and DIT could be classified into three types according to the coverage pattern: Type A, in which areas IV and V were covered by the DIT (27%, 12/44); Type B, in which areas V and VI were covered by the DIT (23%, 10/44); and Type C, in which areas IV, V, and VI were covered by the DIT (50%, 22/44). The superficial part of the masseter consists of not only the muscle belly but also the deep tendon structure. Based on the results obtained in this morphological study, we recommend performing layer-by-layer retrograde injections into the superficial and deep muscle bellies of the masseter.