Botulinum toxin: examining duration of effect in facial aesthetic applications

Exploring Nonresponse to Botulinum Toxin in Aesthetics: Narrative Review of Key Trigger Factors and Effective Management Strategies

Background

Nonresponse to botulinum toxin type A (BoNT-A) has been reported in both medical and aesthetic applications. Secondary nonresponse (SNR) occurs when BoNT-A is initially effective before failure commences at a later point. Most reported cases involve SNR in aesthetics. Several aspects of this complication remain elusive or controversial.

Objective

We aimed to address unanswered questions regarding the prevalence and etiology of SNR. Additionally, we investigated the immunogenicity of BoNT-A formulations, mainly focusing on the development of neutralizing antibodies that hinder the toxin's pharmacologic effects. Furthermore, we sought to examine the management strategies for SNR.

Methods

The PubMed and Google Scholar databases were searched from inception for articles on nonresponse to BoNT-A therapy. Articles were evaluated based on their contribution to the field. Expert opinions and panel recommendations regarding management and data gaps were also included in the review.

Results

There are limited data on SNR prevalence in aesthetic applications compared to therapeutic uses. Trigger factors of SNR include improper handling of BoNT-A; incorrect injection practices; and impurities present in the formulation, such as clostridial complexing proteins that may increase immunogenicity. Other contributing factors include infection; patient characteristics; and treatment parameters that encompass an increased frequency of BoNT-A injections (ie, <3 months apart), higher cumulative dosages, elevated treatment dosages, and booster injections (retreatment within 3 weeks of the initial injection). Neutralizing antibodies developed with first-generation formulations, such as onabotulinumtoxinA and abobotulinumtoxinA that contain clostridial proteins, but not with second-generation BoNT-As, such as incobotulinumtoxinA and daxibotulinumtoxinA, which lack these proteins. Among patients who developed SNR after using first-generation BoNT-A for aesthetic purposes, switching to incobotulinumtoxinA therapy did not result in the development of immune responses. Switching to a protein-free BoNT-A formulation such as incobotulinumtoxinA upon development of SNR has been advocated. To effectively manage SNR, it is crucial to minimize the identified trigger factors.

Conclusions

Nonresponse to BoNT-A is gaining importance in aesthetic treatments. Considering the potential for immunogenicity is essential when selecting a BoNT-A formulation. Preventing SNR is crucial, given the lack of solid data on effective treatments.

Botulinum Toxin in Aesthetic Medicine: A Bibliometric Analysis of Research Trends and Methodological Quality of the Top 100 Cited Publications

Background

Botulinum toxin is widely used in aesthetic medicine, with numerous studies examining its efficacy and safety.

Objectives

This bibliometric analysis aims to describe research trends and assess the methodological quality of the highest-impact botulinum toxin research in aesthetic applications.

Methods

The authors of this study identified the 100 most-cited publications on botulinum toxin in aesthetics using Web of Science, covering all available journal years (from inception to October 2024). The Oxford Centre for Evidence-Based Medicine Level of Evidence (LOE) was used to assess the methodological quality of each study.

Results

The authors identified 1728 articles on the aesthetic uses of botulinum toxin, with the top 100 most-cited articles spanning from 1994 to 2021. The United States dominated the research landscape with 50 articles, followed by Canada (15). The University of California (United States) and the University of British Columbia (Canada) emerged as the top contributing institutions. Among journals, Dermatologic Surgery led in publication count, followed by Plastic and Reconstructive Surgery and Aesthetics Surgery Journal. Notably, Professors Jean Carruthers and Alastair Carruthers from Canada were the leading researchers, topping both publication count and citation metrics. Notably, more than half of the studies were classified as LOE 5 (Expert Opinion/Narrative Review).

Conclusions

This bibliometric analysis reveals a paucity of high-quality studies in the field of botulinum toxin in aesthetic medicine, with research predominantly concentrated in western countries. These findings highlight the need for more rigorous, evidence-based studies and increased global collaboration to advance the understanding and application of botulinum toxin in aesthetics.

Level of Evidence 4 Therapeutic

The effect of botulinum neurotoxin A injections on meibomian glands and dry eye

PURPOSE

To assess the influence of Botulinum neurotoxin A (BoNT-A) injection on meibomian gland function and dry eye in patients diagnosed with Blepharospasm (BPS) and Hemifacial spam (HFS).

METHODS

Adult patients aged 18 years or older who suffer from periocular dystonia, and were treated with BoNT-A injections, were recruited in this interventional prospective study between 2023 and 2024. Each patient was followed up for a period of three months. The following parameters were compared at baseline, 14 and 90 days post BoNT-A injections: Visual acuity, meibography, tear break up time (TBUT), Schirmer test, meibum expression, tear meniscus height, fluorescein corneal staining, meibomian gland dysfunction (MGD) grading, and ocular surface disease index (OSDI). In addition, patients underwent subjective quality of life questionnaire for BPS and HFS.

RESULTS

Thirty-six eyes of twenty-six patients were included in this study. The mean age ±SD was 59 ± 17.33 years. There was a significant statistical difference in vascular changes on the lid margin, TBUT, corneal and conjunctival fluorescein staining and meibum expression (P < 0.001 in all). The differences were statistically significant when compared to baseline vs visit 2, and visit 2 vs visit 3 (p-value<0.05). Jankovic rating scale and HFS score improved significantly between the time periods (P < 0.001 in both). There was no significant difference in meibomian gland loss, tear meniscus height, Schirmer test, and OSDI.

CONCLUSION

BoNT-A injection is an effective treatment for periocular dystonia, but it worsens ocular surface and dry eye disease. Moreover, it affects the meibomian glands by disturbing their secretion.

Effect of zinc or copper supplementation on the efficacy and sustainability of botulinum toxin A "Botox" injection in masseter muscle of albino rats

OBJECTIVES

This study aimed to evaluate whether oral zinc or copper supplementation affected the efficacy and sustainability of botulinum toxin-A (BTX-A) injection in masseter muscle of albino rats.

MATERIALS AND METHODS

32 adult male albino rats were allocated equally into four groups: group I (control), group II received 10U BTX-A injection, group III received 10U BTX-A injection + zinc (1 mg, 4 days pre-injection), and group IV received 10U BTX-A injection + copper (0.04 mg, 7 days post-injection). Rats were euthanized at 2 and 12 weeks (4 rats per subgroup) after injection. The masseter muscle was examined via histological, histochemical, histomorphometrical and real-time polymerase chain reaction (qRT-PCR) analyses.

RESULTS

The histopathological results of the BTX-A group showed atrophied muscle fibers with increased atrophy with time compared to the control group. The BTX-A + zinc group displayed more atrophy compared to BTX-A group. Conversely, the BTX-A + copper group demonstrated improved histology of muscle fibers compared to BTX-A and BTX-A + zinc groups. Histomorphometric analysis of Masson trichrome staining at 2 and 12 weeks revealed that collagen area percentage was the highest in the BTX-A + copper and control groups, followed by BTX-A and BTX-A + zinc groups. At 12 weeks, the nuclear factor kappa beta (NF-κB) mRNA expression was significantly higher in BTX-A + zinc and BTX-A groups compared to BTX-A + copper group and relative to the control group.

CONCLUSION

Zinc supplementation significantly improved the effectiveness and durability of BTX-A, whereas copper supplementation reduced its efficacy.

Different Dilutions of Mesobotox in Facial Rejuvenation: Which is Better?

BACKGROUND

Microbotulinum toxin A treatment is a technique of delivering multiple intradermal injections of diluted botulinum toxin type A into the dermis or the interface between the dermis and the superficial layer of the facial muscles to preserve the facial mobility. The current study aimed to evaluate and compare the clinical effect of different dilutions of microbotulinum toxin A in periorbital and mid-facial rejuvenation.

METHODS

This randomized prospective interventional study included 30 female patients with different types of wrinkles in periorbital and/or mid-face. Patients were divided into three groups: group I (10 patients): 100U botulinum toxin in 5 ml saline, group II (10 patients): 100U botulinum toxin in 7 ml saline and group III (10 patients): 100U botulinum toxin in 10 ml saline.

RESULTS

A statistically significant better global esthetic improvement scale (GAIS) scores after 1 month were observed in group I compared to groups II and III. Also, after 6 months better GAIS scores were observed in group I compared to group II and in group II compared to group III. Assessment of different esthetic parameters measured by the Antera 3D camera revealed a statistically significant improvement in all parameters (periorbital and mid-face) in group I and in most of parameters (periorbital and mid-face) in groups II and III with more evident improvement after 1 month compared to after 6 months.

CONCLUSION

Intradermal microbotulinum toxin A is a cost-effective method for improving periorbital and mid-face wrinkles with a better effect of 1:5 than 1:7 and 1:10 dilutions. Facial wrinkles possess a great burden on patients' psychological status, and the emergence of novel rejuvenation technique with minimal side effects is necessary. MicroBoNT-A usage in the literature was through variety of dilutions and concentrations. Therefore, a conclusive and comparative study was essential to compare the effect of different microBoNT-A dilutions. In this context, the current study aimed to evaluate and compare the clinical effect of different dilutions of microBoNT-A in periorbital and mid-facial rejuvenation.

LEVEL OF EVIDENCE III

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 .

Botulinum Toxin for Pain Relief in Cancer Patients: A Systematic Review of Randomized Controlled Trials

Cancer pain is one of the most disabling symptoms complained by cancer patients, with a crucial impact on physical and psychological well-being. Botulinum neurotoxins (BoNTs) type A and B have emerged as potential interventions for chronic pain; however, their role in these patients is still debated. Thus, this systematic review of randomized controlled trials aimed at assessing the effects of BoNT treatment for cancer pain to guide physicians in an evidence-based approach integrating BoNT in cancer care. Out of 5824 records, 10 RCTs satisfied our eligibility criteria and were included in the present work for a total of 413 subjects with several cancer types (breast, head and neck, esophageal, and thoracic/gastric cancers). While some studies demonstrated significant pain reduction and improved quality of life post-BoNT-A injections, outcomes across different cancer types were inconclusive. Additionally, several effects were observed in functioning, dysphagia, salivary outcomes, esophageal strictures, gastric emptying, and expansions. This review emphasizes the need for further standardized research to conclusively establish the efficacy of BoNT in comprehensive cancer pain management.

Minimally invasive cosmetic procedures for mothers of brides: Strategies and considerations

The pivotal role of the bride's mothers in wedding celebrations is an effective motivation to seek cosmetic therapies, making them frequent patients in a dermatologists' offices. Addressing their aesthetic concerns contributes to their holistic well-being, but faces an intricate relationship between time availability, financial factors, and the critical emotional context. This article underscores the varying behavioral patterns of mothers of brides when seeking aesthetic treatments, providing tailored strategies for effective communication and decision-making, based on individual personalities. Additionally, this paper presents a specific timeline for the implementation of these interventions, including neuromodulators, collagen stimulators, and fillers. Understanding the unique traits and expectations of this particular population can lead to improved patient satisfaction, enhanced outcomes, and an overall positive experience.

The Patient Journey in Facial Aesthetics: Findings from a European Consensus Meeting on Improving the Quality of Life for Patients Receiving Botulinum Toxin Injections

Purpose

Successful treatment of facial lines with botulinum toxin is largely dependent on patient satisfaction; thus, a structured treatment journey that uses patient-reported outcomes (PROs) is helpful for maximizing botulinum toxin results. To develop a patient-centric approach for botulinum toxin injections in facial aesthetics, a group of clinicians met to provide opinions on an optimal treatment journey that uses PROs to quantify treatment benefits on patient quality of life.

Patients and Methods

A multidisciplinary panel of 9 clinicians with expertise in facial aesthetic procedures convened for an advisory board that was preceded by and followed up with a structured, multistep consensus discussion. Based on current literature, the panel's expertise, structured questions, and group discussion, panelists assessed, reconciled, and agreed upon on a patient journey for botulinum toxin treatment in facial aesthetics.

Results

Panelists agreed that an optimal patient journey includes screening, assessment, treatment, posttreatment, and follow-up visits. A compact, easy-to-complete, and digital PRO questionnaire should be provided before the visit. During screening, thorough assessments are integral for a successful patient journey because they provide an opportunity to understand treatment goals, address patient concerns, discuss risks and benefits, obtain medication lists/medical history, and take pretreatment photographs. Treatment strategies should include discussing and educating on the approach/choice of botulinum toxin and ensuring patients are comfortable. Posttreatment, clinicians should request intense muscle movements to enhance product uptake and be available to address patient concerns. Finally, during follow-up, PRO questionnaires can be provided to gauge patient satisfaction with treatment, and pretreatment photographs can be provided to allow patients to track their progression. Follow-ups should be scheduled with new patients or those reporting low satisfaction.

Conclusion

Establishing a relationship, being aware of the patient's goals, and developing an individualized care plan allows for a structured, patient-centered treatment journey that promotes positive aesthetic outcomes.

Neuromodulators for Skin

Neurotoxins are the most popular nonsurgical aesthetic procedure for men and women of all ages. Five botulinum toxin A (BoNTA) products represent the current palette of available BoNTA for cosmetic use. Off-label uses of BoNTA continue to expand and are now used for skin rejuvenation, to treat various skin disorders, and in facial nerve paralysis. Dermal and subdermal injections of dilute BoNTA has grown in popularity and been shown to improve skin texture and quality. Common targets for chemodenervation in facial nerve synkinesis are ipsilateral orbicularis oculi, mentalis, depressor anguli oris, buccinator, corrugator muscles, and the ipsilateral and/or contralateral frontalis.

The Efficacy and Duration of Onabotulinum Toxin A in Improving Upper Facial Expression Lines With 64-Unit Dose Optimization: A Systematic Review and Meta-Analysis With Trial Sequential Analysis of the Randomized Controlled Trials

BACKGROUND

Onabotulinumtoxin A (Onabot A) was the first treatment to be approved for aesthetic indications, namely glabellar lines (GLs), crow's feet lines (CFLs), and forehead lines (FHLs), with a cumulative dose of 64 U.

OBJECTIVES

The aim of this study was to conduct a meta-analysis to combine the available data for approved doses for GLs, CFLs, and FHLs to explore the effect and duration of simultaneous treatment with Onabot A.

METHODS

PubMed/MEDLINE, Embase, and other national clinical trial registries were searched for randomized controlled trials from January 2010 to July 2022. The meta-analysis, trial sequential analysis, and investigator-assessed time to return to nonresponder status in GLs, CFLs, and FHLs following Onabot A were plotted to elicit a cumulative dose-adjusted response curve based on Kaplan-Meier analysis with a log-rank test.

RESULTS

Fourteen randomized controlled trials were eligible for quantitative analysis. A total of 8369 subjects were recruited across the trials. The meta-analysis results show that Onabot A is very effective in reducing moderate to severe GLs, CFLs, and FHLs. The cumulative Z-curve for GLs, CFLs, and FHLs also exceeds the required information size (RIS). Kaplan-Meier analysis with a log-rank test demonstrated that simultaneous treatment of GLs, CFLs, and FHLs requires 182 days (95% CI = 179, 215 days) (P < 0.00002) to return to nonresponder status.

CONCLUSIONS

Treatment of the upper facial expression lines with Onabot A is effective, and the approved cumulative dose of 64 U gives longer-lasting effects.

LEVEL OF EVIDENCE: 1

Functional Deimmunization of Botulinum Neurotoxin Protease Domain via Computationally Driven Library Design and Ultrahigh-Throughput Screening

Botulinum neurotoxin serotype A (BoNT/A) is a widely used cosmetic agent that also has diverse therapeutic applications; however, adverse antidrug immune responses and associated loss of efficacy have been reported in clinical uses. Here, we describe computational design and ultrahigh-throughput screening of a massive BoNT/A light-chain (BoNT/A-LC) library optimized for reduced T cell epitope content and thereby dampened immunogenicity. We developed a functional assay based on bacterial co-expression of BoNT/A-LC library members with a Förster resonance energy transfer (FRET) sensor for BoNT/A-LC enzymatic activity, and we employed high-speed fluorescence-activated cell sorting (FACS) to identify numerous computationally designed variants having wild-type-like enzyme kinetics. Many of these variants exhibited decreased immunogenicity in humanized HLA transgenic mice and manifested in vivo paralytic activity when incorporated into full-length toxin. One variant achieved near-wild-type paralytic potency and a 300% reduction in antidrug antibody response in vivo. Thus, we have achieved a striking level of BoNT/A-LC functional deimmunization by combining computational library design and ultrahigh-throughput screening. This strategy holds promise for deimmunizing other biologics with complex superstructures and mechanisms of action.

A Preclinical Study Comparing the Activity and Potency of OnabotulinumtoxinA and PrabotulinumtoxinA

Objective

The goal of this study was to compare the unit-to-unit biological activity of the vacuum-dried formulation of prabotulinumtoxinA (prabotA) and onabotulinumtoxinA (onabotA) in preclinical assays.

Methods

Reconstituted 100 U vials of prabotA and onabotA were tested in 3 distinct assays: plate-capture light chain activity (PC-LCA), measuringlight chain enzymatic activity after recovery of toxin from reconstituted product using a proprietary toxin capture step; cell-based potency assay (CBPA), measuring the intoxication steps of binding, translocation, and light chain activity (synaptosomal-associated protein 25 [SNAP25] cleavage); and mouse Digit Abduction Score (DAS), evaluating muscle paresis. Each assay tested 3 separate prabotA and onabotA lots on several independent test dates.

Results

Multiple orthogonal assays established that when assessed on a unit-to-unit basis, the biological activity of prabotA is lower than that of onabotA. In the PC-LCA and CBPA assays, onabotA displayed 1.51 ± 0.14-fold higher (mean ± SD) and 1.33 ± 0.07-fold higher (mean of pooled lots ± SEM) activity than prabotA, respectively. Similarly, the mouse DAS data showed that onabotA had 1.4 ± 0.1-fold higher (mean ± SEM) potency than prabotA. Results of all 3 assays demonstrated differences in potency, efficacy, and duration of action between onabotA and prabotA on a unit-to-unit basis.

Conclusion

Preclinical assays established differences in the biological activity of onabotA and prabotA, supporting that the units of biological activity are not interchangeable.

Efficacy and safety of long-term botulinum toxin treatment for acquired cervical dystonia: a 25-year follow-up

Botulinum toxin A (BoNT/A) is the first-line treatment for idiopathic cervical dystonia (ICD) and is widely used in the clinical setting. To date, scanty data are available on the effectiveness of BoNT in treating acquired cervical dystonia (ACD). Here we present a long-term follow-up of ACD patients treated with BoNT/A that focused on safety and efficacy. The study included subjects who had received at least six treatments of three commercially available BoNT/A drugs [abobotulinumtoxinA (A/Abo), incobotulinumtoxinA (A/Inco) and onabotulinumtoxinA (A/Ona)]. Safety and efficacy were assessed based on patients' self-reports regarding adverse effects (AE), duration of improvement of dystonia and/or pain relief. Global clinical improvement was measured on a six-point scale. 23 patients with ACD were administered 739 treatments (A/Abo in 235, A/Inco in 72, A/Ona in 432) with a mean number of treatments of 31 ± 20 (range 6-76) and duration of 10 ± 6 weeks (range 2-25). The mean dose was 737 ± 292 U for A/Abo, 138 ± 108 U for A/Inco and 158 ± 80 U for A/Ona. The average benefit duration was 89 ± 26 (A/Abo), 88 ± 30 days (A/Inco), and 99 ± 55 days (A/Ona) (p = 0.011); global clinical improvement for all sessions was 4 ± 1. ANOVA one-way analysis indicated that A/Ona had the best profile in terms of duration (p < 0.05), whereas A/Abo had the best pain relief effect (p = 0.002). Side effects were reported in 9% of treatments (67/739), with ten treatments (1%) complicated by two side effects. Most side effects were rated mild to moderate; severe side effects occurred following three treatments with the three different BoNT; two required medical intervention. No allergic reactions were reported. Even after 25 years of repeated treatments, all serotypes of BoNT demonstrate positive effects in treating ACD with long-lasting efficacy and safety.

Risk Factor-Driven Prehabilitation Prior to Abdominal Wall Reconstruction to Improve Postoperative Outcome. A Narrative Review

All abdominal wall reconstructions find themselves on a scale, varying between simple to highly complex procedures. The level of complexity depends on many factors that are divided into patient comorbidities, hernia characteristics, and wound characteristics. Preoperative identification of modifiable risk factors provides the opportunity for patient optimization. Because this so called prehabilitation greatly improves postoperative outcome, reconstructive surgery should not be scheduled before all modifiable risk factors are optimized to a point where no further improvement can be expected. In this review, we discuss the importance of preoperative risk factor recognition, identify modifiable risk factors, and utilize options for patient prehabilitation, all aiming to improve postoperative outcome and therewith long-term success of the reconstruction.

Efficacy and Safety of DaxibotulinumtoxinA for Injection in the Treatment of Glabellar Lines by Age and Race: Subgroup Analysis of the SAKURA Clinical Trials

BACKGROUND

DaxibotulinumtoxinA for Injection (DAXI) is a novel botulinum toxin type A formulation approved for the treatment of glabellar lines. The efficacy, safety, and extended duration of response of DAXI 40 U for glabellar lines were demonstrated in 2 Phase 3, randomized, double-blind studies (SAKURA 1 and 2) and a Phase 3 open-label trial (SAKURA 3).

OBJECTIVES

The aim of this study was to evaluate the efficacy and safety of the first DAXI 40 U treatment received in SAKURA 1, 2, or 3 across age and race subgroups.

METHODS

Adults with moderate-to-severe glabellar lines (Investigator Global Assessment-Frown Wrinkle Severity [IGA-FWS] and Patient FWS [PFWS] scales) were evaluated for glabellar line severity for ≤36 weeks after the first DAXI treatment. Efficacy and safety were analyzed by age (18-45, >45-55, and >55 years) and race (Asian, Black and African American, and White).

RESULTS

Overall, 2785 patients were included in the efficacy analysis. The proportion of patients achieving none or mild glabellar line severity at maximum frown (IGA-FWS) after DAXI treatment was high in all age and race subgroups (>96% at Week 4). Glabellar line severity of none or mild by composite IGA-FWS and PFWS rating was maintained for a median of 24.0 weeks in all age subgroups, and for 27.0, 25.3, and 24.0 weeks in the Asian, Black and African American, and White subgroups, respectively. Treatment-emergent adverse events were similar across all subgroups.

CONCLUSIONS

Consistent with the overall study population, DAXI 40 U demonstrated a high response rate and duration of effect of ≥24 weeks across all age and race subgroups.

Comparison of Effectiveness and Safety of a Botulinum Toxin Monotherapy and a Combination Therapy with Hyaluronic Acid Filler for Improving Glabellar Frown

BACKGROUND

Among numerous cosmetic procedures for face rejuvenation performed all over the world, botulinum toxin type A (BoNT-A) for wrinkles is one of the most widely practiced procedures. However, for severe frowns, the application of botulinum toxin is often insufficient. In this study, the effects of hyaluronic acid filler combination therapy and the BoNT-A alone were evaluated.

METHODS

Forty subjects with 2 or higher points (moderate to severe) of a facial wrinkle scale (FWS) when frowning in the glabellar area were assigned to 2 group: Botulinum toxin type A monotherapy group and a combination regimen of the toxin and hyaluronic acid filler group. Subjects visited outpatient department every 4 weeks until 28 weeks after the injection, and the assessment of the efficacy using FWS, subject satisfaction at both resting and maximum frowning and safety analysis were performed.

RESULTS

Subjects of both group was administered 18U of BoNT-A and the subjects of the combination group received additional 0.45mL of hyaluronic acid filler regimen. Both at rest and maximum frown, the combination group scored lower FWS than the toxin and showed significance in the week-20 and week-28. And at final visit, subject satisfaction score of the combination was higher than that of toxin group.

CONCLUSION

For patients with moderate to severe glabellar frown, the combined administration of BoNT-A and hyaluronic acid filler could be a considerable treatment for improving wrinkles.

LEVEL OF EVIDENCE III

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 .

Long-term Effects of Repeated Botulinum Toxin Injection in Cosmetic Therapeutics

BACKGROUND

Botulinum toxin (BT), a potent neurotoxin, has been used in clinical medicine since the 1970s for cosmetic and therapeutic purposes. Studies have consistently shown positive outcomes with a very limited adverse effect profile and a conventional understanding that results dissipate after 3 to 5 months. However, more recent evidence suggests that changes in muscle composition, function, and appearance persist for much longer, even years. To examine the potential implications of these findings on cosmetic use of BT injections in reduction of skin lines and wrinkles, we first needed to further our understanding of the current literature on long-term outcomes after repeated BT injections.

METHODS

A comprehensive review of the literature on long-term outcomes after repeated BT injections for cosmetic indications was performed. We evaluated the study designs, and results were compared.

RESULTS

A total of 22 publications met our inclusion criteria, of which 14 were clinical trials. Few studies extended outcome measurement past 6 months postinjection, and many were funded or supported by industry. However, the studies that extended follow-up saw persistent changes after BT injection, in some cases as far as 4 years postinjection.

CONCLUSION

The current body of knowledge on the long-term results after repeated cosmetic BT injections is very limited, and the available literature provides insufficient evidence on how prolonged effects could alter clinical use of BT. Further clinical studies with extended follow-up periods with inclusion of both subjective and objective measured outcomes of appearance and muscle function are required to better understand the long-term impacts of repeated BT injections.

The Action of Botulinum Toxin A on the Sternocleidomastoid Muscle: An Experimental Study on Rats

In this study, we aim to investigate the effective dose of botulinum neurotoxin A that results in paralysis of the sternocleidomastoid muscle for a minimum duration of 28 days in Wistar rats. This research is the first in a series of studies to investigate the value of botulinum toxin A in the healing of clavicle fractures through the temporary paralysis of the sternocleidomastoid. A surgical incision was made under general anaesthesia, and botulinum neurotoxin A in respective doses of 4 and 6 international units (IU) or normal saline in equivalent volumes were injected directly into the exposed muscle. Electromyography was conducted on days 0, 7, and 28 following substance administration to determine the extent of muscle paralysis. Electromyography on day 0 showed no paralysis in either group. Animals injected with neurotoxin all exhibited paralysis on days 7 and 28 that was weaker in the group injected with the smaller dose of 4 IU. One death occurred in the group injected with the higher dose (6 IU), whereas in the control group, no paralysis was seen. Botulinum neurotoxin A in a dose of 6 IU resulted in complete paralysis of the sternocleidomastoid in rats for a minimum of 28 days. A dose of 4 IU resulted in less potent paralysis but was safer in our research. Botulinum neurotoxin is a substance utilised in cosmetics and therapeutics for many years, yet research shows that its use can be expanded to target a wider range of pathologies. In this series of studies, we aim to explore the neurotoxin's applications on the treatment of clavicle fractures. To investigate this, we need to first establish the duration of its action on the sternocleidomastoid muscle.

Time to onset and duration of botulinum toxin efficacy in movement disorders

Background

Botulinum toxin (BoNT) is a valuable treatment in movement disorders; however, time to onset and duration of efficacy may widely differ among patients. We aimed to clarify the impact of main demographic and clinical features on time to onset and duration of BoNT efficacy.

Methods

We analyzed time-to-onset and duration of BoNT efficacy in 186 consecutive patients treated with BoNT for blepharospasm, cervical dystonia, facial hemispasm, oromandibular dystonia, limb dystonia, and sialorrhea due to Parkinsonism. The following factors were considered as potential efficacy predictors: doses and types of toxin, sex, age, years of treatment, and clinical condition. Kruskall–Wallis, Spearman correlation, and multivariate linear regression were used for statistical analysis.

Results

The average time to onset was 6.7 ± 5 days and duration of BONT efficacy 78.5 ± 28.4 days. Both time to onset and duration of efficacy were correlated with BoNT doses (p: 0.007 and p: 0.02). The multiple regression analysis showed that sex, age, years of BoNT treatment, doses, type of toxin, and clinical condition significantly predicted time to onset (F(11, 171) = 2.146, p: 0.020) with age being the strongest predictor (p: 0.004).

The same model explained 20.1% of the variance of duration of BoNT efficacy, showing a significant prediction of the outcome (F(11, 164) = 3.754, p < 0.001), with doses (p < 0.001), type of toxin (p: 0.017), and clinical condition (p < 0.001) being the strongest predictors.

Conclusion

Our findings suggest that age, type of toxin, clinical condition and especially doses may account for the variability of BoNT efficacy in terms of time to onset and duration.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-022-10995-2.

High Anal Canal Pressure and Rectal Washouts Contribute to the Decrease of Anal Basal Pressure After Botulinum Toxin Injections in Paediatric Patients With Chronic Constipation

INTRODUCTION

Chronic constipation can be treated by injecting botulinum toxin into the anal sphincter to decrease anal basal pressure. To assess the effect of botulinum toxin, we investigated the factors that contribute to changes in anal basal pressure after injection.

METHODS

This was a retrospective study conducted in a tertiary hospital in the Netherlands. We included children with chronic constipation treated with botulinum toxin injections and measured anal basal pressure before and after each injection. Multivariable linear regression analyses were used.

RESULTS

We investigated 30 cases with idiopathic constipation. Their median age was 20.5 (7.75-53.25) months. Anal basal pressure decreased after injection in 20 cases. The mean decrease of anal basal pressure after injection was 18.17 ± 35.22 mmHg. The anal basal pressure change was linearly correlated with preinjection pressure (R ² = 0.593, P < 0.001). A significant decrease of pressure was observed in patients with preinjection pressure > 70 mmHg. Preinjection anal basal pressure (β = -0.913, P < 0.001) and rectal washouts (β = -21.015, P = 0.007) contributed significantly to pressure changes. Changes in anal basal pressure were also significantly associated with patients' weights (β = 0.512, 95% CI, 0.011-1.013) and sex (β = 22.971, 95% CI, 9.205-36.736).

CONCLUSIONS

Botulinum toxin significantly decreases anal basal pressure when preinjection pressure is higher than 70 mmHg. In patients with severely elevated anal basal pressure, we recommend rectal washouts to promote the decrease of anal basal pressure.

A Randomized, Single-Blind, Crossover Study Evaluating the Impact of OnabotulinumtoxinA Treatment on Mood and Appearance During the COVID-19 Pandemic

Background

The emergence of Coronavirus disease of 2019 (COVID-19), quickly became one of the most severe disease outbreaks in modern history. This caused many aesthetic practices around the country to close temporarily and led to a unique time period to evaluate the impact neurotoxin has in the setting of an ongoing pandemic.

Objectives

To examine whether the administration of onabotulinumtoxinA (BOTOX Cosmetic, Allergan plc, Coolock, Ireland), in regular users, synergistically amplifies the elevation in mood/happiness, self-satisfaction with appearance and overall satisfaction, in the context of the ongoing pandemic.

Methods

A randomized single-blind cross-over study was designed to evaluate the impact of neurotoxin treatment in the upper third of the face on mood, self-satisfaction with appearance, and overall satisfaction. The placebo group crossed over to treatment after 1 month. Surveys evaluating patient happiness, self-satisfaction with appearance and overall efficacy were completed among both groups, and again to the placebo group again following crossover to treatment.

Results

Forty-five subjects were enrolled with 30 in the treatment and 15 in the control/cross-over group. The placebo group demonstrated no change in happiness or self-satisfaction in appearance until cross-over to the treatment group. Both groups, once receiving, onabotulinumtoxinA reported increased happiness, self-satisfaction with appearance and overall treatment satisfaction.

Conclusions

OnabotulinumtoxinA treatment to the upper face in the midst of the COVID-19 pandemic was found to increase patient happiness, self-satisfaction with appearance, and overall treatment satisfaction.

Comparative Effectiveness of Injection Therapies for Hemiplegic Shoulder Pain in Stroke: A Systematic Review and Network Meta-Analysis

Hemiplegic shoulder pain (HSP) hampers post-stroke functional recovery and is not well managed with conservative treatments. This systematic review aimed to examine the various injection therapies for HSP and investigate their effectiveness at different time points. The protocol of this meta-analysis was registered on INPLASY with a registration number of INPLASY202180010. PubMed, EMBASE, and Scopus were searched from their inception to 4 August 2021 for the clinical studies investigating comparative effectiveness of different injection regimens for treating hemiplegic shoulder pain in patients with stroke. The primary outcome was the weighted mean difference (WMD) on the visual analog scale (VAS) of pain reduction in the fourth-week and between the fourth and twenty-fourth weeks. Ranking probabilities of the WMD for each treatment were obtained using simulations. Seventeen studies with 595 participants were included. The network meta-analysis showed that at the fourth-week, intra-muscular botulinum toxin (BoNT) injections and suprascapular nerve blocks (SSNB) were superior to a placebo, with WMDs of 1.55 (95% CI, 0.09 to 3.01) and 1.44 (95% CI, 0.07 to 2.80), respectively. SSNB possessed the highest probability (53.3%) and appeared to be the best treatment in the fourth-week, followed by intra-muscular BoNT injections (42.6%). Intramuscular BoNT injections were better than the placebo, with a WMD of 1.57 (95% CI, 0.30 to 2.84) between the 4th and 24th weeks. Intramuscular BoNT injections had the highest probability (79.8%) as the best treatment between the 4th and 24th weeks. SSNB was likely to rank first in relieving HSP at the fourth post-treatment week, whereas intra-muscular BoNT injections had the highest probability to achieve the best treatment effectiveness in the post-injection period between the fourth and twenty-fourth weeks. However, as some of the included studies used a non-randomized controlled design, more randomized controlled trials are needed in the future to validate and better understand the short- and long-term efficacy of different injection therapies for management of HSP.

Long-term therapy with botulinum toxin in facial synkinesis: Retrospective data analysis of data from 1998 to 2018

OBJECTIVES

Treatment with botulinum toxin A (BoNT) is the therapy of choice for many patients with facial synkinesis. Repeated injections relieve hypertonicity and hyperkinesis of reinnervated mimic muscles. Aim of the study was to prove if the injection regime and dosage of BoNT change during long-time therapy.

DESIGN

Retrospective analysis of patients´ data, who were treated for synkinesis with BoNT from 1998 to 2018.

SETTING

Tertiary referral facial nerve centre.

PARTICIPANTS

Injection pattern of BoNT was based on clinical symptoms, observations of the specialist and on previous treatment pattern. Onabotulinumtoxin (OnaBoNT), Incobotulinumtoxin (IncoBoNT) and Abobotulinumtoxin (AboBoNT) were available for treatment. Patients consulted our department for following treatment as soon as the symptoms re-occurred.

MAIN OUTCOME MEASURES

Change in dosage and injection pattern, the time intervals between treatments over the entire therapy period.

RESULTS

Seventy-three patients were repeatedly injected. The median number of treatments was 18, the median treatment interval was 3.0 months. During the initial treatment, orbicularis oculi and the mentalis muscles were the most frequently injected muscles (94%). During repeated treatment, the number of injected muscles increased significantly (P < .0001), whereas the dose per muscle remained stable. The initial dose was 24 U (95%-CI 22-27 U) for OnaBoNT and IncoBoNT; 69 U for AboBoNT(95%-CI 44-94 U). We observed a significant increase in dosage for OnaBoNT and IncoBoNT (P < .0001) during the long-term therapy. The time intervals between treatments were stable for all three BoNT preparations (P > .05).

CONCLUSIONS

We observed significant change in treatment dose and injection pattern of BoNT in patients with facial synkinesis. These results provide an orientation in dose finding and injection regimen of BoNT in the long-term course of therapy.

The mechanisms of action and use of botulinum neurotoxin type A in aesthetics: Key Clinical Postulates II

BACKGROUND

The literature on botulinum neurotoxin type A (BoNT-A) is extensive, often contradictory, and confounded by a competitive market of products and research attempting to distinguish brand individuality.

METHODS

A comprehensive review of literature on the principles of BoNT-A in aesthetics as well as clinical examples.

RESULTS

In 2017, the Eight Key Clinical Postulates were formulated as a guide for the aesthetic practitioner in understanding BoNT-A pharmacodynamics and to compare different toxins. These are now updated to include (a) All type A toxins act identically; (b) The mathematical relationship between toxin and receptor is the basis of efficacy, and clinical efficacy is influenced by molecular potency and patient attributes including muscle mass, gender, age, and ethnicity; (c) Efficacy, onset, and duration are functions of "molecular potency" defined as the number of active 150 kDa molecules available for binding; (d) "Molecular potency" is difficult to objectively quantify for commercially available toxins; (e) Up to a point, increased molecular potency decreases time to onset and increases duration of effect, and the "Molecular Potency Quotient" is a construct for comparing molecular potency commercial cost; (f) The area of effect of a toxin injection is dependent upon molecular potency, diffusion (passive), and spread (active); (g) Differing reconstitution volumes; and (h) Increased number of injection sites can affect spread, onset, and duration of effect.

CONCLUSIONS

The principles of BoNT-A use in aesthetics are complex yet understandable as outlined in the framework of the updated Eight Key Clinical Postulates and serves as a useful tool for providing the most effective treatment and interpreting research on present and future toxin formulations.

Botulinum Toxin A as a Treatment for Provoked Vestibulodynia: A Randomized Controlled Trial

OBJECTIVE

To evaluate pain reduction after two injections of 50 units botulinum toxin A compared with placebo for provoked vestibulodynia.

METHODS

We conducted a double-blinded, placebo-controlled randomized trial of 50 units botulinum toxin A or placebo injected in the bulbocavernosus muscles twice, 3 months apart, in women with provoked vestibulodynia. Primary outcome was self-reported dyspareunia or pain at tampon use on a visual analog scale (VAS, 0-100). Secondary outcomes were pain at weekly tampon insertion (VAS score), reduction of pelvic floor hypertonicity (measured with a vaginal manometer), adverse events, and sexual function and distress. A sample size of 38 participants for each group was calculated to achieve a statistical power of 80% based on an effect size of 20 VAS units (0-100) (mean score range 56-76±31 SD).

RESULTS

Between May 2016 and June 2018, 124 women with provoked vestibulodynia were assessed, and 88 were randomized to botulinum toxin A (BTA group, n=44) or placebo (placebo group, n=44). Primary outcome showed a lower but statistically nonsignificant pain rating by 7 VAS units (95% CI -15.0 to 0.4) in the BTA group compared with the placebo group. Secondary results showed a significant decrease in pain at weekly tampon insertion by 11 VAS units (95% CI -16.6 to 6.0) with botulinum toxin A injection. The vaginal manometer measured lower maximum contraction strength by 7 mm Hg (95% CI -12.7 to -2.4) and lower 10-second endurance strength by 4 mm Hg (95% CI -7.72 to -1.16) in the BTA group compared with the placebo group. No changes were observed for sexual function and distress, but there was a significant increase in women attempting vaginal intercourse in the BTA group (0.27, 95% CI 0.06-0.48). No severe adverse events were reported.

CONCLUSION

Twice-repeated injections of 50 units of botulinum toxin A in women with provoked vestibulodynia did not reduce dyspareunia or pain at tampon use, but secondary outcomes suggested positive effects of the treatment.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT02773641.

Repeated intrastriatal application of botulinum neurotoxin-A did not influence choline acetyltransferase-immunoreactive interneurons in hemiparkinsonian rat brain - A histological, stereological and correlational analysis

In Parkinson's disease, dopamine depletion leads to hyperactivity of cholinergic interneurons in the caudate-putamen (CPu). Botulinum neurotoxin-A (BoNT-A) inhibits the release of acetylcholine in the peripheral nervous system and is also thought to act as a local anticholinergic drug when injected intrastriatally. In hemiparkinsonian (hemi-PD) rats, a unilateral intrastriatal injection of 1 ng BoNT-A significantly diminished apomorphine-induced rotation behavior for at least 3 months, the effect fading thereafter. A second intrastriatal BoNT-A application, 6 months after the first one, led to a stronger and longer-lasting, beneficial behavioral reaction. As a single BoNT-A injection was not cytotoxic in the rat striatum and resembled BoNT-A treatment in clinical practice, here, we investigated the structural outcome of repeated intrastriatal BoNT-A injections with respect to striatal volume, the number of choline acetyltransferase-immunoreactive (ChAT-ir) interneurons and of the length of their dendritic arbors, and the numeric density of ChAT-ir BoNT-A-induced varicosities (BiVs). Repeated unilateral intrastriatal BoNT-A application decreased the volume of the injected CPu, but did not significantly change the number of striatal ChAT-ir interneurons. Also, the total dendrite length of ChAT-ir interneurons after repeated BoNT-A application resembled the values in double vehicle-injected hemi-PD rats. In repeatedly BoNT-A-injected hemi-PD rats, the numeric density of ChAT-ir BiVs in the CPu was increased compared with rats only intrastriatally injected once with BoNT-A. Even repeated BoNT-A injections in rat striata did not cause substantial morphological changes in ChAT-ir neuron, except for the increased numeric density of ChAT-ir BiVs.

Botulinum toxin B suppresses the pressure ulcer formation in cutaneous ischemia-reperfusion injury mouse model: Possible regulation of oxidative and endoplasmic reticulum stress

BACKGROUND

We previously identified that botulinum toxin A (BTX-A) suppressed pressure ulcer (PU) formation after cutaneous ischemia-reperfusion (I/R) injury; however, regulation of cutaneous I/R-induced oxidative and endoplasmic reticulum (ER) stress by BTX-B was not investigated. Additionally, the efficacy of BTX-B injection has never been examined.

OBJECTIVE

Objective was to assess the effects of BTX-B on the formation of PU by cutaneous I/R injury, and the regulation of oxidative and ER stress in I/R injury by BTX-B.

METHODS

BTX-B was subcutaneously injected into I/R area, and wound size, vascular damage, hypoxic area, and apoptotic cells in I/R area were analyzed. We evaluated the extent of oxidative and ER stress in I/R area by using OKD48 mice and ERAI mice, respectively, which enabled evaluating oxidative and ER stress through bioluminescence detection.

RESULTS

BTX-B injection significantly suppressed the formation of PU by cutaneous I/R injury. Cutaneous I/R-induced vascular damage, hypoxic area, and number of oxidative-damaged cells and apoptotic cells were suppressed by BTX-B injection. BTX-B administration significantly inhibited I/R-induced oxidative stress signal in OKD48 mice. BTX-B reduced the I/R-induced oxidative stress-associated factors. BTX-B significantly inhibited the oxidant-induced reactive oxygen species and apoptosis of endothelial cells and fibroblasts. BTX-B significantly inhibited I/R-induced ER stress signal in ERAI mice. Cutaneous I/R injury-induced ER stress-response factors and GRP78/BiP and CHOP-positive cells in I/R area were significantly decreased by BTX-B injection.

CONCLUSION

BTX-B injection might have protective effects against PU formation after cutaneous I/R injury by reducing vascular damage, hypoxia-induced oxidative and ER stress, and apoptosis.

Repeated Intrastriatal Botulinum Neurotoxin-A Injection in Hemiparkinsonian Rats Increased the Beneficial Effect on Rotational Behavior

Injection of botulinum neurotoxin-A (BoNT-A) into the striatum of hemiparkinsonian (hemi-PD) rats reduced apomorphine-induced rotation behavior significantly, for at least 3 months. Thereafter, rotation behavior increased again. We injected hemi-PD rats with 1 ng BoNT-A twice, the second injection following 6 months after the first one and tested the rats for apomorphine-induced rotations and spontaneous motor behaviors, i.e., corridor task and stepping test. To test the hypothesis that BoNT-A reduced striatal hypercholinism in hemi-PD rats, the acetylcholinesterase inhibitor donepezil was injected prior to separate apomorphine-induced rotation tests. In hemi-PD rats, the first BoNT-A injection led to a clear reduction of the apomorphine-induced rotations, and the second BoNT-A injection to a more massive and prolonged reaction. In hemi-PD rats whose apomorphine-induced rotation behavior was strongly reduced by an intrastriatal BoNT-A, subsequent donepezil injections led to significant increases of the rotation rate. Concerning corridor task and stepping test, neither first nor second BoNT-A injections changed hemi-PD rats' behavior significantly. The data give evidence for the possibility of repeated intrastriatal administrations of BoNT-A, for treatment of motor symptoms in experimental hemi-PD over a longer time.

Botulinum neurotoxin formulations: overcoming the confusion

Botulinum toxin A is produced by anaerobic spore-forming bacteria and is used for various therapeutic and cosmetic purposes. Botulinum toxin A injections are the most popular nonsurgical procedure worldwide. Despite an increased demand for botulinum toxin A injections, the clinical pharmacology and differences in formulation of commonly available products are poorly understood. The various products available in the market are unique and vary in terms of units, chemical properties, biological activities, and weight, and are therefore not interchangeable. For safe clinical practice and to achieve optimal results, the practitioners need to understand the clinical issues of potency, conversion ratio, and safety issues (toxin spread and immunogenicity). In this paper, the basic clinical pharmacology of botulinum toxin A and differences between onabotulinum toxin A, abobotulinum toxin A, and incobotulinum toxin A are discussed.

Injectable and topical neurotoxins in dermatology: Basic science, anatomy, and therapeutic agents

Botulinum toxin is a potentially deadly anaerobic bacterial toxin that acts by inhibiting release of acetylcholine at the neuromuscular junction, thereby inhibiting contraction of the exposed striated muscle. There are currently 4 botulinum toxin preparations approved by the US Food and Drug Administration (FDA): onabotulinumtoxin, abobotulinumtoxin, incobotulinumtoxin and rimabotulinumtoxin. While significant overlap exists, each product has unique properties and specifications, including dosing, diffusion, and storage. Extensive physician knowledge of facial anatomy, coupled with key differences of the various neurotoxin types, is essential for safe and successful treatments. The first article in this continuing medical education series reviews key characteristics of each neurotoxin, including new and upcoming agents, and provides an anatomic overview of the most commonly injected cosmetic sites.

Duration of Clinical Efficacy of OnabotulinumtoxinA in Crow's Feet Lines: Results from Two Multicenter, Randomized, Controlled Trials

BACKGROUND

Duration of esthetic treatments may contribute to subject satisfaction.

OBJECTIVE

Describe response duration with onabotulinumtoxinA in crow's feet lines (CFL) and the association of duration with perception of improvement.

METHODS

Subjects from 2 double-blind, placebo-controlled trials received onabotulinumtoxinA 24 U in CFL; Study 2 subjects could also receive 20 U in glabella. At Day 30, responders achieved ≥1-grade improvement in Facial Wrinkle Scale (FWS) scores. Median duration of effect for responders and for responders stratified by Subject's Global Assessment of Change in CFL (SGA-CFL) was determined.

RESULTS

Of 1,362 subjects, 833 received onabotulinumtoxinA. In Study 2, 305 subjects also received 20 U in glabella. In Study 1 (150-day follow-up), per investigator and subject assessments, respectively, median response duration was 125 and 144 days for dynamic lines and 137 and 148 days for static lines. Median response duration for dynamic and static lines in Study 2 (120-day follow-up) was 119 to 121 days per investigator and subject assessments. Subjects reporting greater improvement on the SGA-CFL tended to have a longer duration of response on investigator FWS scores at maximum smile.

CONCLUSION

Response duration with onabotulinumtoxinA in CFL was ≥4 months. Subject perception of CFL improvement may be associated with response duration.

Botulinum Toxin and Muscle Atrophy: A Wanted or Unwanted Effect

While the facial rejuvenating effect of botulinum toxin type A is well known and widespread, its use in body and facial contouring is less common. We first describe its use for deliberate muscle volume reduction, and then document instances of unanticipated and undesirable muscle atrophy. Finally, we investigate the potential long-term adverse effects of botulinum toxin-induced muscle atrophy. Although the use of botulinum toxin type A in the cosmetic patient has been extensively studied, there are several questions yet to be addressed. Does prolonged botulinum toxin treatment increase its duration of action? What is the mechanism of muscle atrophy and what is the cause of its reversibility once treatment has stopped? We proceed to examine how prolonged chemodenervation with botulinum toxin can increase its duration of effect and potentially contribute to muscle atrophy. Instances of inadvertent botulinum toxin-induced atrophy are also described. These include the "hourglass deformity" secondary to botulinum toxin type A treatment for migraine headaches, and a patient with atrophy of multiple facial muscles from injections for hemifacial spasm. Numerous reports demonstrate that muscle atrophy after botulinum toxin type A treatment occurs and is both reversible and temporary, with current literature supporting the notion that repeated chemodenervation with botulinum toxin likely responsible for both therapeutic and incidental temporary muscle atrophy. Furthermore, duration of response may be increased with subsequent treatments, thus minimizing frequency of reinjection. Practitioners should be aware of the temporary and reversible effect of botulinum toxin-induced muscle atrophy and be prepared to reassure patients on this matter.

The role of neurotoxins in the periorbital and midfacial areas

Initially popularized for the treatment of strabismus and blepharospasm, injection of botulinum neurotoxin has become the most commonly performed cosmetic treatment in the United States. Injection techniques have been particularly well-studied in the midface and periocular region, and patient satisfaction tends to be very high. We review the salient differences among available neurotoxins, how to optimally reconstitute them, how to inject the forehead, glabella, lateral canthal lines ("crow's feet"), infralid region, and transverse nasal lines ("bunny lines"), how to sculpt the brow, and how to manage potential complications.

Subject satisfaction with onabotulinumtoxinA treatment of glabellar and lateral canthal lines using a new patient-reported outcome measure

BACKGROUND

Patient satisfaction with treatment is an important outcome in facial aesthetic medicine.

OBJECTIVE

To evaluate subject satisfaction with onabotulinumtoxinA treatment of glabellar lines (GL) and crow's feet lines (CFL) using the validated Facial Line Satisfaction Questionnaire (FLSQ).

METHODS

In this randomized double-blind study, subjects with moderate/severe GL and CFL received onabotulinumtoxinA (20 U, GL; 24 U, CFL) or placebo. Over 120 days, the following were assessed: satisfaction, achievement of treatment expectations, satisfaction with duration of treatment (FLSQ), severity of GL and CFL (Facial Wrinkle Scale [FWS]), and aesthetic improvement (Global Aesthetic Improvement Scale).

RESULTS

Satisfaction in the per-protocol population was significantly greater at Day 60 in the onabotulinumtoxinA group (n = 60) compared with placebo (n = 57) for GL (81.7% vs 0%; p < .001). Most subjects treated with onabotulinumtoxinA remained satisfied up to 120 days. Achievement of treatment expectations (86.7%; Day 60), satisfaction (81.7%; Day 60), and satisfaction with the duration of treatment (61.6%; Day 90) were significantly better with onabotulinumtoxinA than placebo (p < .001) for GL and CFL combined. Efficacy (FWS) and aesthetic improvement were observed in most subjects at Days 30 and 60, respectively.

CONCLUSION

High satisfaction rates are achieved and sustained in subjects treated with onabotulinumtoxinA for GL and CFL combined.

Therapeutic use of botulinum toxin in migraine: mechanisms of action

Migraine pain represents sensations arising from the activation of trigeminal afferents, which innervate the meningeal vasculature and project to the trigeminal nucleus caudalis (TNC). Pain secondary to meningeal input is referred to extracranial regions innervated by somatic afferents that project to homologous regions in the TNC. Such viscerosomatic convergence accounts for referral of migraine pain arising from meningeal afferents to particular extracranial dermatomes. Botulinum toxins (BoNTs) delivered into extracranial dermatomes are effective in and approved for treating chronic migraine pain. Aside from their well-described effect upon motor endplates, BoNTs are also taken up in local afferent nerve terminals where they cleave soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins, and prevent local terminal release. However, a local extracranial effect of BoNT cannot account for allthe effects of BoNT upon migraine. We now know that peripherally delivered BoNTs are taken up in sensory afferents and transported to cleave SNARE proteins in the ganglion and TNC, prevent evoked afferent release and downstream activation. Such effects upon somatic input (as from the face) likewise would not alone account for block of input from converging meningeal afferents. This current work suggests that BoNTs may undergo transcytosis to cleave SNAREs in second-order neurons or in adjacent afferent terminals. Finally, while SNAREs mediate exocytotic release, they are also involved in transport of channels and receptors involved in facilitated pain states. The role of such post-synaptic effects of BoNT action in migraine remains to be determined.

Aesthetic uses of the botulinum toxin

The cosmetic use of botulinum toxin (BoNT) is the most common cosmetic procedure performed in the world today. Common adverse events seen in the aesthetic use of the BoNT include swelling, localized bruising, headaches, injection site discomfort, excessive muscle weakness, and unintended paresis of adjacent muscles. BoNT has a wide array of cosmetic uses, including treatment of glabellar lines, chemical browlift, forehead wrinkles, periorbital, and perioral lines. The future formulations and applications of BoNT type A will be plentiful, and are exciting to consider.

Skin Biomechanical Changes after Injection of Onabotulinum Toxin A: Prospective Assessment of Elasticity and Pliability

OBJECTIVE

This study aimed to test the hypothesis that the administration of onabotulinum toxin A will result in an increase in skin pliability and elasticity.

STUDY DESIGN

A prospective case series with planned data collection in which patients were treated with onabotulinum toxin and assessed at baseline, 2 weeks post-injection, and 2 months post-injection.

SETTING

A private cosmetic surgery clinic associated with a tertiary academic hospital.

SUBJECTS AND METHODS

Forty women were prospectively enrolled to receive onabotulinum toxin A into their glabella, forehead, and lateral orbit. Outcomes were assessed at baseline, 2 weeks posttreatment, and 2 months posttreatment using the Cutometer MPA 580. Skin pliability (Uf) and the elastic recoil (Ua/Uf) were recorded as the 2 primary outcome measures.

RESULTS

There was a significant effect of onabotulinum toxin on skin elasticity (f = 47.8, P = .001) with a mean (+/- SE) increase in elastic recoil of 20% (4.4%) for the glabellar region (P < .001) and 18% (4.0%) for the lateral orbit (P < .0001). There was a significant effect of the treatment on skin pliability (f = 46.9, P < .001) with a mean (+/- SE) increase of 26% (5.4%) for the lateral orbit (P = .001) and 52% (8.3%) for the glabellar region (P < .001).

CONCLUSION

Injection of onabotulinum toxin into the lateral orbital, forehead, and glabellar regions results in skin that has increased pliability as well as increased elastic recoil. Although this study demonstrates the positive effect of onabotulinum toxin on biomechanical parameters, it is unclear what specific histological changes are occurring within the skin.

A comparative assessment of three formulations of botulinum toxin A for facial rhytides: a systematic review and meta-analyses

BACKGROUND

Botulinum toxin A is a commonly used biological medication in the field of facial plastic surgery. Currently, there are three distinct formulations of botulinum toxin A, each with their purported benefits and advantages. However, there is considerable confusion as to the relative efficacy and side-effects associated with each formulation. Therefore, the purpose of this paper is to systematically assess published studies and perform a meta-analysis to determine if there is a significant advantage of any of the individual formulations.

METHODS/DESIGN

A systematic literature search was performed for all relevant English language randomized controlled trials using Embase, Cumulative Index to Nursing and Allied Health Literature (CINAHL), MEDLINE, World Health Organization (WHO) International Clinical Trials Registry Platform, European Union (EU) Clinical Trials Register, Cochrane Library databases of clinical trials, and ClinicalTrials.gov. Inclusion criteria included any randomized controlled trial (RCT) that assessed the use of botulinum toxin for cosmetic purposes. The included articles were also analyzed for bias using the Cochrane Collaboration's tool for assessing the risk of bias in RCTs.

DISCUSSION

The results of this review will provide clinicians with an unbiased, high level of evidence of the comparative efficacy of individual preparations of botulinum toxin A.

Onset, longevity, and patient satisfaction with incobotulinumtoxinA for the treatment of glabellar frown lines: a single-arm, prospective clinical study

BACKGROUND

IncobotulinumtoxinA (Bocouture(®)) is free from complexing proteins and effective for treating glabellar frown lines.

PURPOSE

To determine the efficacy, onset, and duration of action of incobotulinumtoxinA for the treatment of glabellar frown lines.

PATIENTS AND METHODS

In this single-arm, prospective, proof-of-concept study, 23 patients were treated with 25 U incobotulinumtoxinA, equally split between five injection sites in the glabella. Severity of glabellar frown lines was rated by an independent rater from standardized photographs using the validated Merz 5-point scale at several visits over 5 months following treatment. To assess patient satisfaction, patients completed a questionnaire before and 2 weeks after treatment.

RESULTS

The percentage of responders at maximum frown 2-4 days after treatment was 95.2% and 85.0% when responders were defined as patients with ≥ 1-point and ≥ 2-point improvement on the 5-point scale compared with baseline, respectively. At this time point, 84% of the maximum effect had occurred. The responder rate at maximum frown, according to both definitions, was 100% for at least the next two visits (days 8 ± 1 and 14 ± 2). At all visits, the change from baseline in the mean glabellar frown-line score at maximum frown was statistically significant, with on average an almost 1-point improvement from baseline 5 months after treatment.

CONCLUSION

IncobotulinumtoxinA is an effective and well-tolerated treatment for glabellar frown lines, with a rapid onset of action and a long duration of effect lasting for more than 5 months.

An in vivo analysis of the effect and duration of treatment with botulinum toxin type A using digital image speckle correlation

BACKGROUND

Use of Botulinum toxin type A (BTX-A) for facial wrinkles is well-documented, but current methods of subjective evaluation by clinicians and patients fail to objectively quantify the magnitude and duration of facial muscle paralysis.

OBJECTIVE

(a) Determine the locus of facial muscular tension; (b) Quantify and monitor muscular paralysis and subsequent return; (c) Continuously correlate the appearance of wrinkles and muscular tension using non-invasive digital image speckle correlation (DISC) to measure treatment efficacy; (d) Corroborate objective data with existing rating scales (subject global assessment and facial lines outcome-11).

METHODS

Two sequential images of slight facial motion (frowning, raising eyebrows) are taken with a camera for n = 6 patients pre- and post-treatment at different time points up to 24 weeks. DISC processes the images to produce a vector map of muscular displacement to obtain spatially resolved information regarding facial tension.

RESULTS

We observed maximum paralysis (≥70%) at 2 weeks, and the rate of recovery varied widely ranging from 2 to 5 months, with two patients continuing to exhibit reduced contraction at 24 weeks. Vector analysis of pre-treatment contraction correctly predicted injection site and illustrated lines of maximum tension.

CONCLUSIONS

Digital image speckle correlation can precisely track the degree of contraction of different muscle groups following BTX-A injection. It can help predict injection site, quantify muscle paralysis, and monitor the recovery following BTX-A injection. Results were found to be reproducible across six patients.