Tailored botulinum toxin type A injections in aesthetic medicine: consensus panel recommendations for treating the forehead based on individual facial anatomy and muscle tone

Anatomical considerations of medial eye wrinkles: Guidelines for botulinum neurotoxin injections

Crow's feet lines in the lateral canthal region are a common concern among aging patients, initially appearing as dynamic wrinkles during facial expressions and becoming more pronounced with age. Botulinum neurotoxin temporarily paralyzes muscles by inhibiting acetylcholine release, smoothing wrinkles and enhancing skin's youthful appearance. Effective treatment requires tailored approaches considering individual anatomy and muscle activity. Recent cadaveric studies identified the tear trough muscle, emphasizing its role in infraorbital support and aging. Clinically, patients often present medial eye wrinkles after BoNT treatment for crow's feet, prompting exploration of underlying mechanisms and management strategies. Three cases demonstrated that medial BoNT injections in the orbicularis oculi muscle significantly improve medial eye wrinkles and tear trough appearance. The study underscores the importance of understanding muscle hyperactivity and anatomical variations for precise treatment. Enhanced injection techniques targeting specific areas can achieve better outcomes and minimize complications, particularly in culturally sensitive regions where facial expressions are valued. This research highlights the necessity for comprehensive anatomical knowledge and patient-specific treatment strategies to address medial eye wrinkles effectively.

Optimized Aesthetic Outcomes When Treating Glabellar Lines with Botulinum Toxin Type A: GLO 3 + 2: A Precise Technique Based on Anatomy

Good patient outcomes after treatment of the glabellar complex with botulinum toxin type A entail elimination of glabellar lines and maintenance of a natural eyebrow position. A precise injection technique that accurately targets the muscles that influence eyebrow position is required to reduce the risk of adverse aesthetic outcomes or unmasking an underlying eyelid ptosis. Here, we describe the glabellar lines optimization (GLO 3 + 2) injection anatomy technique, a precise five-point injection pattern that is based on current understanding of facial functional anatomy and which aims to minimize the risk of affecting nontargeted muscles. Injection sites above the brow or that do not target the precise location of the muscles in the glabellar complex are likely to inadvertently expose the frontalis to botulinum toxin type A and result in undesirable aesthetic outcomes. Because the frontalis is a strong determinant of aesthetic outcomes, it is important to consider the overall effects of the interactions between the eyebrow depressors and the opposing forces of the frontalis on brow outcomes in both the resting brow position and during dynamic brow movement.

Impact of Glabellar Injection Technique With DaxibotulinumtoxinA for Injection on Brow Position

BACKGROUND

Precise injection technique is vital for avoiding suboptimal eyebrow position when treating glabellar lines with botulinum toxin type A.

OBJECTIVES

The aim of this study was to evaluate the impact of glabellar injection technique on eyebrow position in patients treated with DaxibotulinumtoxinA for Injection (DAXI).

METHODS

This retrospective post hoc analysis involved 60 adults who received a single treatment with DAXI 40 U to the glabella and had standardized facial photography. Median vertical and horizontal displacement of the brows (at rest) at baseline and 2 weeks after glabellar injection were measured. Brow position outcomes were evaluated by an oculoplastic surgeon and expert anatomist. Investigators were interviewed to ascertain individual injection techniques.

RESULTS

Precise injection location and depth, and median resting brow position following treatment varied between investigators. Positive brow outcomes were achieved with deep DAXI injections into the medial corrugator, superficial lateral corrugator injections placed between the midpupil and lateral limbus, and deep midline procerus injections. Glabellar injection technique that more precisely targeted the corrugator muscles resulted in longer glabellar line treatment duration compared to a less targeted technique. Medial corrugator injections above the medial brow; lateral corrugator injections administered deeply or more medially, toward the medial third of the brow; and procerus injections superior to the inferomedial brow tended to be associated with suboptimal outcomes that were more apparent during dynamic expression.

CONCLUSIONS

Aesthetically pleasing brow outcomes and greater duration of efficacy can be achieved with an injection pattern that precisely treats the anatomic location of the corrugator supercilii and procerus muscles, avoiding the frontalis.

LEVEL OF EVIDENCE: 4

Impact of DaxibotulinumtoxinA for Injection on Brow Position and Frontalis Muscle Activity Following Treatment of Glabellar Lines

BACKGROUND

Botulinum toxin type A (BoNTA) injections for the treatment of facial lines may lead to pleasant or undesirable changes in eyebrow height and position.

OBJECTIVES

The aim of this study was to evaluate the impact of glabellar injection of DaxibotulinumtoxinA for Injection (DAXI), a novel BoNTA formulation, on eyebrow position and frontalis activity.

METHODS

This study involved the post hoc analysis of adult patients from the Phase 2a forehead lines (FHL, N = 60) and open-label safety (OLS, N = 175) studies who received a single dose of DAXI 40 U to the glabella and for whom facial photographs were taken at rest and at maximum eyebrow elevation. Median vertical and horizontal displacement of the brows and median forehead strain (an objective quantitative assessment of frontalis activity) from baseline to 2 weeks after glabellar DAXI injection were measured.

RESULTS

Two weeks after glabellar DAXI injection, vertical eyebrow movement (at rest) of the lateral brow was observed. In both studies, vertical movement was greatest in the lateral (0.6-0.9 mm) and mid (0.5-0.7 mm) brow regions; movement in the medial brow was negligible (0-0.23 mm). In both studies, a graded reduction in forehead strain was observed 2 weeks post glabellar DAXI injection, with the greatest reduction being in the lower segment (FHL, -73%; OLS, -82%). Treatment with DAXI showed improvements in FHL wrinkle severity.

CONCLUSIONS

Glabellar injection of DAXI showed a positive reduction in dynamic frontalis activity that maintained or had a positive effect on eyebrow position. Vertical movement of the brow was suggestive of an improved eyebrow shape with a mild lateral arch.

LEVEL OF EVIDENCE: 4

Integrative Assessment for Optimizing Aesthetic Outcomes When Treating Glabellar Lines With Botulinum Toxin Type A: An Appreciation of the Role of the Frontalis

Despite the perception that treatment of glabellar lines with botulinum toxin A is straightforward, the reality is that the glabellar region contains a number of interrelated muscles. To avoid adverse outcomes, practitioners need to appreciate how treatment of 1 facial muscle group influences the relative dominance of others. In particular, practitioners need to understand the independent role of the frontalis in eyebrow outcomes and the potential for negative outcomes if the lower frontalis is unintentionally weakened by botulinum toxin A treatment. In addition, practitioners must recognize how inter-individual variation in the depth, shape, and muscle fiber orientation among the upper facial muscles can affect outcomes. For optimal results, treatment of the glabellar complex requires a systematic and individualized approach based on anatomical principles of opposing muscle actions rather than a one-size-fits-all approach. This review provides the anatomical justification for the importance of an integrated assessment of the upper facial muscles and eyebrow position prior to glabellar treatment. In addition, a systematic and broad evaluation system is provided that can be employed by practitioners to more comprehensively assess the glabellar region in order to optimize outcomes and avoid negatively impacting resting brow position and dynamic brow movement.

LEVEL OF EVIDENCE: 5

Use of LetibotulinumtoxinA for Aesthetic Treatment of Asians: A Consensus

Treatment of wrinkles and dynamic lines with botulinum toxin has been a routine practice for years in aesthetic clinical settings. The effective treatment of wrinkles requires a comprehensive understanding of facial expression muscles and their interactions, the mechanism of action of botulinum toxin, and individual patient preferences. The dose adjustment practice and injection technique of physicians are affected by cultural differences; most Asian patients prefer natural-looking results. This article aims to present an expert consensus on the injection sites, doses, and levels of botulinum toxin for various indications in Asians, with the hope of providing guidance to some clinicians. This consensus paper reviews LetibotulinumtoxinA for patient evaluation, dosage, and delivery techniques in Asians from the time LetibotulinumtoxinA was approved up to December 2022. Panelists proposed individualized treatment plans for botulinum toxin type A (BTxA) treatments in 3 areas-wrinkle removal, contour adjustment, and face lifting-for Asians based on their extensive experience and knowledge of facial anatomy. When using a different BTxA, clinicians should start with a conservative dose and carefully individualize the treatment for each patient, and adjust it according to feedback to obtain a higher satisfaction level.

LEVEL OF EVIDENCE: 5

SAMCEP Society consensus on the treatment of upper facial lines with botulinum neurotoxin type A: A tailored approach

BACKGROUND

The safety and efficacy of botulinum neurotoxin type A (BoNTA) treatments are well established, but injection techniques, target muscles, and toxin doses continue to evolve, with each refinement producing improvements in treatment outcomes. The recommendations in this consensus move away from standard templates and illustrate how to tailor treatments to individual patterns and strengths of muscle activity, and patient preferences.

METHODS

Seventeen experts in the fields of plastic surgery, dermatology, ophthalmology, otorhinolaryngology, and neurology convened in 2022 to develop consensus-based recommendations for the use of botulinum toxin A for the treatment of horizontal forehead lines, glabellar frown lines, and crow's feet lines that reflect current clinical practice. The focus was on how to tailor injections to individual patients to optimize treatment outcomes.

RESULTS

For each upper face indication, consensus members describe how to perform a dynamic assessment to optimize the dose and injection technique for each patient. A tailored treatment protocol is presented for commonly observed patterns of dynamic lines. Units of Inco are defined and the precise location of injection points, illustrated with the use of anatomical images.

CONCLUSION

This consensus provides up-to-date recommendations on the tailored treatment of upper facial lines based on the latest research and collective clinical experience of the expert injectors. Optimal outcomes require thorough patient evaluation, both at rest and during animation, using both visual and tactile cues; detailed understanding of facial muscular anatomy and how opposing muscles interact; and use of a BoNTA with high precision to target identified zones of excess muscle activity.

Dynamic Evaluation of Skin Displacement by the Frontalis Muscle Contraction Using Three-Dimensional Skin Displacement Vector Analysis

PURPOSE

Understanding the muscle actions and resultant skin movement can enable more safe and effective botulinum toxin injection for the treatment of forehead wrinkles. We aimed to investigate skin displacement patterns of the forehead and adjacent skin due to frontalis muscle contraction using three-dimensional skin vector displacement analysis.

MATERIALS AND METHODS

Thirty healthy individuals were enrolled. Photographs of the face were taken at rest and during maximal contraction of the frontalis muscle. Each expression image was aligned to its respective static image to compute the differences in the skin position.

RESULTS

When frontalis muscle contracts, forehead skin displacement vectors were mostly vertical (63.4%), followed by lateral oblique (33.3%) and medial oblique (3.3%). In 53.3%, only the lower part of the forehead moved upward, while 40.0% showed bidirectional skin movement with transition line at a mean distance of 59.4 mm above the pupil. Moreover, 86.7% showed asymmetric skin displacement, and 83.3% showed both glabellar and eyebrow skin displacement. Frontalis muscle contraction also induced medial 2/3 (50.0%) or entire (33.3%) skin movement of the temple.

CONCLUSION

Botulinum toxin injection into the forehead can be individualized by considering the vector and asymmetry of skin displacement. Vertical or medial vector requires more centrally located injections, while laterial vector requires more laterally located injections. The presence and location of the vertical transition line are important for preventing ptosis when treating forehead lines with botulinum toxin. Glabellar movement during frontalis contraction suggests the need for a concomitant injection into the glabella to prevent glabella wrinkle accentuation.

Real-World, Retrospective, Multicenter, Observational Study on the Use of the First Liquid AbobotulinumtoxinA in Italy

INTRODUCTION

Randomized controlled trials (RCTs) suggested that liquid formulation of botulinum toxin type A (aboBoNT-A) is safe and effective, but data confirming these characteristics in a real-life heterogenous set of patients are currently lacking. This study aimed to assess the efficacy and safety of the ready-to-use aboBoNT-A solution in adults with moderate-to-severe glabellar wrinkles.

METHODS

In this real-life, multicenter, retrospective, observational study, healthy adults were treated at baseline only with aboBoNT-A solution on the glabellar area and followed up for 24 weeks. Re-treatment after 20-24 weeks could also be combined with other aesthetic procedures. Family history of immune-mediated inflammatory diseases (IMIDs) was not an exclusion criterion. Patient-reported outcomes (patient's satisfaction and injection-related pain) and physician-reported outcomes (Physician Global Assessment, PGA) were collected.

RESULTS

Of the 542 patients enrolled in the study, 38 had IMID family history. Injection-related pain was reported in 128 (23.62%) as mild (pain VAS = 1.34 ± 0.87) mainly by non-botulinum toxin treatment-naïve women under 50 years of age. At 48 h, physicians rated the clinical result as "improved" in 64% of patients, conversely 264 patients (48.71%) self-evaluated as "satisfied"/"very satisfied". At 4 weeks a touch-up (< 10 units) was performed in 11 (2.03%) patients and 98.2% were "highly satisfied". Re-treatment was performed in 330 (61.45%) patients, mainly botulinum-experienced, at 20 weeks and in 207 (38.55%), mainly botulinum naïve, at 24 weeks. A total of 403 (74.35%) patients were re-treated with the three-point technique and 201 (37.08%) also received hyaluronic acid filler in the lower central face and middle third. There were no cases of de novo IMIDs.

CONCLUSIONS

Real-world data confirmed that aboBoNT-A is a fast, efficient, durable, reproducible, and easy-to-use drug which is also well tolerated in patients with family history of IMID.

Treatment of Upper Facial Lines With DaxibotulinumtoxinA for Injection: Results From an Open-Label Phase 2 Study

BACKGROUND

Simultaneous treatment of moderate-to-severe upper facial lines is reflective of real-world clinical practice.

OBJECTIVE

To evaluate the efficacy and safety of daxibotulinumtoxinA-lanm for injection (DAXI) for simultaneous treatment of glabellar, forehead, and lateral canthal (LC) lines.

METHODS

In this open-label, single-arm Phase 2 study, patients (48 enrolled, 94% completed, follow-up 24-36 weeks) received DAXI 40U (glabellar), 32U (forehead), and 48U (LC) lines. Key efficacy endpoints: percentages of patients achieving none/mild wrinkle severity (investigator-rated) for each upper facial line scale at Week 4.

RESULTS

At Week 4, most patients achieved none/mild wrinkle severity (investigator-rated): glabellar (96%), forehead (96%), and LC (92%). Median times to loss of none/mild response (investigator- and patient-rated) among all patients were: 24.6 (glabellar), 20.9 (forehead), and 24.9 (LC) weeks; and 25.0, 24.0, and 28.1 weeks, respectively, among Week-4 responders. At Week 4, most patients reported improvements (Global Aesthetic Improvement Scale: 96%-98%) and high satisfaction rates (85%-98%). Five patients experienced treatment-related adverse events: injection-site erythema (3 patients/7 events), facial discomfort (2 patients/2 events), and headache (1 patient/1 event). No patients experienced eyebrow or eyelid ptosis.

CONCLUSION

Simultaneous treatment of upper facial lines with DAXI was well tolerated and demonstrated high response rates, extended duration, and high patient satisfaction.

CLINICAL TRIAL REGISTRY

https://clinicaltrials.gov/ct2/show/NCT04259086.

Creating Lift in the Lower Face With Botulinum Toxin A Treatment: An Anatomical Overview With Videos and Case Studies Illustrating Patient Evaluation and Treatment

Background

Relaxation of depressor muscles in the lower face with botulinum toxin A (BoNT-A) can create a lifting effect and dramatically improve jawline contour and resting facial expression. Even with the recent increase in interest in lower face rejuvenation, BoNT-A is a relatively under-recognized tool for treatment of this area. When treating the lower face, an understanding of anatomy and the relationship between the facial muscles is especially important, as injection patterns must be customized for consistently positive outcomes.

Objectives

This study was aimed to provide basic knowledge of the activities of the muscles in the lower face and neck and to describe the basis for injecting BoNT-A to create lift in this area. Expert guidance for injection is also provided.

Methods

As part of a continuing medical education course on differentiating botulinum toxin products, a panel of 4 expert physician injectors participated in a live webinar to discuss the implications of increasing toxin use.

Results

The practical guidance in this manuscript is based on the most frequently requested information by audience members and the information considered critical for success by the authors. The authors outline the functional anatomy of the lower face most relevant for BoNT-A treatment and case studies as well as methods for patient evaluation and injection technique are also provided. Videos showing treatment planning and injection technique for the lower face and neck are included.

Conclusions

BoNT-A is an important nonsurgical tool for creating lift in the lower face.

Level of Evidence 5

Consensus on the Use of Hyaluronic Acid Fillers from the Cohesive Polydensified Matrix Range: Best Practice in Specific Facial Indications

Background

As the treatment indications for the Cohesive Polydensified Matrix^® hyaluronic acid (CPM-HA) portfolio continue to expand and diversify, injectors new to the range or those who are expanding the treatments they offer may be unsure of the optimal product and injection technique for specific facial areas. Each product in the CPM-HA portfolio has been intentionally designed to provide the best physical properties for a specific indication and target tissue. This document has been developed to provide a comprehensive, one-stop reference for clinicians using the portfolio.

Methods

An international panel of experts in the field of aesthetic medicine convened to develop guidelines on effective and safe injection technique when performing treatments with the CPM-HA range of soft-tissue fillers.

Results

Consensus members considered treatment indications in the upper, middle and lower face. Landmark deficiencies and anatomical considerations are described for each indication and consensus recommendations provided on the optimal product, injection depth and treatment technique. This is supplemented by the experts advice on avoidance of complications. Throughout, an evidence-based approach to selection of products and injection techniques is provided. The result is a fully tailored approach to a range of indications covering the full portfolio of CPM-HA products, including the newest addition for skin revitalization.

Conclusion

The recommendations in this consensus document are provided to assist clinicians in the selection of CPM-HA products, administration techniques and depths of injection with the aim of providing seamless and natural treatment results, enhanced safety and patient satisfaction.

[New botulinum toxins for aesthetic dermatology : A comprehensive review]

Facial rejuvenation is gaining immense popularity among patients and clinicians. Botulinum toxins derived from bacteria are well-tolerated options as minimally invasive interventions for facial rejuvenation or other aesthetic procedures. These products have revolutionized aesthetic treatments. Several types of botulinum toxins (BoNT) are available. Currently type A and B are clinically used and only BoNT‑A products are approved for use for cosmetic indications in the Germany and the United States. Each product is unique in terms of its composition. Understanding the various BoNT‑A products is essential in choosing the optimal treatment for our patients. In this article we discuss different BoNT‑A products used for aesthetic intervention.

Association Between Secondary Botulinum Toxin A Treatment Failure in Cosmetic Indication and Anti-Complexing Protein Antibody Production

Introduction

Botulinum toxin A (BoT/A) treatment failure (BTF) affects patients subjected to repeated BoT/A exposure for cosmetic indications. BoT/A’s general formulation contains core BoT/A and complexing proteins. BTF may be caused by antibody-induced treatment failure. Antibodies against core BoT/A can occur; however, anti-complexing protein antibodies have never been demonstrated, and tools for anti-complexing protein antibody detection have not been developed. The aim of this study was to evaluate immune involvement in BoT/A-nonresponsive patients.

Methods

Patients suspected of nonresponsiveness to BoT/A for cosmetic indications were recruited. All volunteers were categorized as BoT/A-responsive or BoT/A-tolerant according to frontalis testing with onabotulinumtoxinA (onaA). Twenty-two BoT/A-tolerant volunteers were recruited separately for frontalis testing with incobotulinumtoxinA (incoA). Anti-BoT/A and anti-complexing protein antibodies were quantified by special ELISA using sera from blood sampled before and after frontalis testing.

Results

Significantly higher levels of IgG against complexing protein were detected in onaA-tolerant sera but not in onaA-responders, leading to proposals that anti-complexing protein antibodies could cause onaA unresponsiveness. Some onaA-tolerant patients according to frontalis test with incoA were responsive to incoA. Newly developed absorption ELISA confirmed that incoA-responsive sera predominantly contained IgG against complexing proteins, whereas incoA-tolerant sera contained significant levels of IgG against core BoT/A. The presence of anti-complexing protein antibodies higher than 90.75% in sera of onaA-tolerant patients could respond to incoA. The ELISA technique might be employed as a tool to predict incoA responsiveness. Our frontalis testing after incoA treatment showed that anti-incoA IgG levels were not increased by incoA.

Conclusions

BoT/A-exposed patients may develop antibodies against core botulinum toxin and complexing proteins. Our study is the first to demonstrate that anti-complexing protein antibodies cause BTF. High levels of antibodies against complexing proteins can cause onaA unresponsiveness, although some patients were still incoA-responsive. Our developed ELISA to detect anti-complexing protein antibodies can determine whether onaA-tolerant patients respond to incoA without incoA frontalis testing.

Botulinum Toxin to Treat Horizontal Forehead Lines: A Refined Injection Pattern Accommodating the Lower Frontalis

BACKGROUND

When treating horizontal forehead lines with botulinum toxin type A the traditional approach requires that injection points should stay 1.5 to 2 cm above the orbital rim to avoid brow ptosis. Failure to treat the lower frontalis may potentially cause worse rhytides in the lower forehead.

OBJECTIVES

The aim of this study was to present a refined injection pattern accommodating the lower frontalis and evaluate its clinical efficacy and safety.

METHODS

Patients were categorized into 4 types according to the patterns of their forehead wrinkles. Moderate and severe wrinkles in the upper forehead were treated by the "safe zone" technique. Mild wrinkles and rhytides in the lower forehead were treated by the Microbotox technique. Standard photographs and measurements were taken before and after treatment. The effect on wrinkle reduction and changes in brow heights were assessed.

RESULTS

In total, 330 treatments were followed up in the clinic, and 246 treatments were followed up by telephone. Among the 330 treatments, 213 were evaluated in our clinic 2 to 4 weeks later, and the patients who received these treatments were recruited for effect evaluation and brow height measurements. The posttreatment severity of forehead wrinkles was significantly reduced (P < 0.05), and brow heights remained unchanged (P > 0.05). No severe adverse events were documented. Patient satisfaction was quite high.

CONCLUSIONS

The refined injection pattern is an effective and safe technique to treat horizontal forehead lines. The Microbotox technique enables treatment of the lower frontalis without changes in brow position.

LEVEL OF EVIDENCE: 3

The Bidirectional Movement of the Frontalis Muscle: Introducing the Line of Convergence and Its Potential Clinical Relevance

BACKGROUND

Cosmetic treatment of the forehead using neuromodulators is challenging. To avoid adverse events, the underlying anatomy has to be understood and thoughtfully targeted. Clinical observations indicate that eyebrow ptosis can be avoided if neuromodulators are injected in the upper forehead, despite the frontalis muscle being the primary elevator.

METHODS

Twenty-seven healthy volunteers (11 men and 16 women) with a mean age of 37.5 ± 13.7 years (range, 22 to 73 years) and of diverse ethnicity (14 Caucasians, four African Americans, three Asians, and six of Middle Eastern descent) were enrolled. Skin displacement vector analyses were conducted on maximal frontalis muscle contraction to calculate magnitude and direction of forehead skin movement.

RESULTS

In 100 percent of investigated volunteers, a bidirectional movement of the forehead skin was observed: the skin of the lower forehead moved cranially, whereas the skin of the upper forehead moved caudally. Both movements converged at a horizontal forehead line termed the line of convergence, or C-line. The position of the C-line relative to the total height of the forehead was 60.9 ± 10.2 percent in men and 60.6 ± 9.6 percent in women (p = 0.941). Independent of sex, the C-line was located at the second horizontal forehead line when counting from superior to inferior (men, n = 2; women, n = 2). No difference across ethnicities was detected.

CONCLUSIONS

The identification of the C-line may potentially guide practitioners toward more predictable outcomes for forehead neuromodulator injections. Injections above the C-line could mitigate the risk of neuromodulator-induced brow ptosis.

A personalized treatment approach of frontalis muscle with botulinum toxin A (Bont-A) related to functional anatomy: case studies

Background: The forehead is one of the most frequent sites of botulinum toxin (Bont-A) application. To date, few data are available about the anatomy of the frontalis muscle. Its anatomy is highly heterogeneous in Caucasian people. Consequently, personalized treatments with botulinum toxin-A (Bont-A) are needed to obtain good esthetic results and to reduce side effects. Recently, a study on cadavers found four anatomical shapes of the frontalis muscle, corresponding to four horizontal wrinkle patterns in live patients.Objective: To perform a personalized, reproducible, and safer treatment with Bont-A of the forehead, by classifying patients according to four specific anatomical shapes of the frontalis muscle related to skin wrinkle patterns during contraction.Methods: We treated four patients classified according to the four anatomic types (I, II, III, and IV). The patients' forehead was divided into 21 areas and matched with 4 horizontal wrinkle patterns. Detecting different activities of the muscle in the different areas of the forehead, treatment injections were performed with a different dose, dilution, and at different anatomical layers (intramuscular or intradermal) per point.Conclusions: We confirmed four different wrinkle patterns after forehead contraction according to the anatomical shape of the frontalis muscle. This allows us to perform a tailored treatment with Bont-A. Nevertheless, some patients with atypical patterns still need "ad hoc" treatment.

A 3D Morphometrical Evaluation of Brow Position After Standardized Botulinum Toxin A Treatment of the Forehead and Glabella

BACKGROUND

Botulinum toxin treatment for forehead wrinkles has been extensively studied and found to be a safe and reproducible procedure. However, the effect on the position of the eyebrows, which relies on the dynamic positioning of the treated muscles, has received less attention and has not been studied with 3-dimensional (3D) technology.

OBJECTIVES

The authors sought to evaluate the changes of eyebrow position after standardized botulinum toxin treatment of glabella or glabella and frontalis muscles with 3D imaging.

METHODS

In a prospective study, 2 groups of adult females were treated with botulinum toxin A at the glabella only (G) or at the glabella and the frontalis muscle (F/G). The brow position was measured at 5 positions with 3D photography before injection and 2 weeks, 3 months, and 6 months after injection. Results were statistically analyzed and related to patient age.

RESULTS

In the F/G group, the brow descended significantly almost across the whole brow length after 2 weeks. The descent lessened after 3 months and moved medially. No clear trend was evident in the G group. There was no significant change attributed to patient age in both groups.

CONCLUSIONS

Botulinum toxin treatment of the glabella and frontalis muscle impacts the position and configuration of the eyebrow. The degree of change is affected by the amount of frontalis weakening rather than by treatment of the glabella. While age in general is not a reliable predictor, individual factors play the major role in how pronounced a change of the brow can be expected.

LEVEL OF EVIDENCE: 2

Maximizing botulinum toxin injections for cosmetic and therapeutic applications with a single use, disposable, exact dose injection assist device

Background

Although freehand injection of botulinum toxin remains the status quo, it is an inaccurate technique for delivering precise amounts of neurotoxin at multiple injection sites with expediency. We developed an inexpensive, ergonomic, single-use, disposable exostructure device that rapidly converts a standard syringe into a highly accurate injection instrument.

Materials and methods

Based on the results of two independent injectors, we determined the comparative delivery dose accuracy, precision, and amount of product waste associated with a standard syringe using the freehand injection technique vs a prototype injection assist device. Fifteen experienced injectors were also surveyed regarding their satisfaction using the device in a controlled research setting.

Results

The average percentage difference from the expected dose value was <1% (0.00024 mL) for 1-unit doses (ie, 0.025 mL) with the injection assist device. In contrast, accuracy values with the freehand method were more than 10 times worse (ie, >10% or 0.0025 mL). Accuracy estimates were also superior with the device over freehand for 2- and 4-unit doses. Precision estimates favored the device for all comparisons and all dosing regimens. The magnitude of variability around the average difference ranged from 2.2 to 5.4 times worse for the freehand method compared to the device. The overall percentage of product waste was substantial with the freehand method (>10%) compared to the device (4.3%) (P=0.04) for 1-unit injections. The percentage of injections showing measurable product waste was also significantly lower with the device (78% vs 25%, P=0.01). Fourteen of 15 (93%) injectors surveyed would use the device in daily practice if it were included complimentary with the neurotoxin.

Conclusion

The injection assist device offered superior accuracy and precision compared to the freehand method across the entire injection regimen. The ancillary finding of a significant reduction in product waste with the device was particularly notable.