Botulinum Toxin, Immunologic Considerations with Long-Term Repeated Use, with Emphasis on Cosmetic Applications

Does botulinum toxin have any role in the management of chronic pain associated with bruxism?

OBJECTIVE

To determine the efficacy of injectable botulinum toxin (BTA) in the management of pain associated with nocturnal bruxism.

METHODS

The study subjects consisted of 40 male and female volunteers who complained of chronic pain in the masseter muscles bilaterally due to bruxism. Twenty units of BTA were injected bilaterally into the masseter muscles. Clinical parameters of pain at rest and chewing were assessed at baseline, 2, 4, 8, 12, 16, 18, and 24 weeks using the visual pain scale (VPS).

RESULTS

The study included 24 females and 16 males aged 21 to 52 years (mean 33.9 ± 31.0). The mean VPS score on the first day was 5.75 (SD 1.9), significantly decreasing after two weeks to 0.44 (SD 0.727). The mean difference of VPS from 8 weeks up to 24 weeks gradually increase from 0.69 at 8 weeks to 2.00 at 24 weeks.

CONCLUSION

This study provides evidence that BTA could reduce the pain of nocturnal bruxism in affected patients.

Bruxism and Botulinum Injection: Challenges and Insights

Botulinum toxin (BTA) is a bacterial-derived extract that can inhibit muscle contraction, acting directly on the absorption of acetylcholine. Thanks to this property, botulinum has been used in aesthetic and general medicine for several years. Nowadays, the use of botulinum toxin is being deepened to address the problem of bruxism. In this scoping review, the results of the studies in the literature of the last 10 years were analyzed. Indeed, 12 reports (found on PubMed, Web of Science, and Scopus, entering the keywords "BRUXISM" and "BOTULINUM TOXIN") were deemed eligible for inclusion in this review. In the studies reviewed, BTA was injected into different muscle groups: masseters, masseter and temporalis or masseter, temporalis, and medial pterygoid. Botulinum toxin injection is a viable therapeutic solution, especially in patients with poor compliance or without improvement in conventional treatment.

Effectiveness of Botulinum Toxin Injection on Bruxism: A Systematic Review and Meta-analysis of Randomized Controlled Trials

OBJECTIVE

The present study compiled evidence on the efficacy of botulinum toxin A (BTX) for management of bruxism.

METHODS

A literature review that included randomized control, cohort, as well as observational studies published between January 2000 and November 2022 was conducted. All studies related to BTX injections administered into the masseters of patients with bruxism were included. Primary outcomes were measured by performing a meta-analysis of changes in maximal biting forces and pain severity and meta-regression of the effects of the BTX dose.

RESULTS

Ten studies were included for quantitative analysis. The analysis of the maximal biting force after BTX injections demonstrated a significant reduction at 1 month or less compared with both oral splints (P < 0.000001) and saline injections (P = 0.01). BTX continued to outperform oral splinting (P = 0.001) and saline placebos (P = 0.03) at 3 months. Between 3 and 6 months, a significantly higher maximal biting strength was observed in the BTX group than the oral splinting group (P < 0.00001). No significant differences in the maximal biting force were observed between the BTX and saline placebo groups (P = 0.50). A similar trend was observed in the analysis of pain reduction after botulinum treatment. Additionally, for every unit increase in the BTX dose, pain severity decreased by 0.0831 points (P = 0.0011).

CONCLUSION

BTX is effective in reducing biting strength and pain severity. BTX effects are evident at less than 4 weeks, peak between 5 and 8 weeks, and last for up to 24 weeks. Higher BTX doses result in greater improvement in pain. Although BTX benefits manifest earlier, they gradually diminish, and oral splinting exerts a more enduring effect, especially after 9-12 weeks. BTX injections into masseters are recommended as management options for bruxers, especially for those having difficulties complying with wearing oral splints or those seeking earlier symptom relief. However, future studies should determine BTX effects beyond 24 weeks and after repetitive injections and how bruxers of different ages or genders respond to treatment.

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 .

Emerging Trends in Botulinum Neurotoxin A Resistance: An International Multidisciplinary Review and Consensus

Botulinum neurotoxin A (BoNT-A) injection is the most widely performed aesthetic procedure and a first-line therapeutic option for various medical conditions. The potential for BoNT-A immunoresistance and secondary nonresponse related to neutralizing antibody (NAb) formation warrants attention as the range of BoNT-A aesthetic applications continues to expand.

Methods

An international multidisciplinary panel reviewed published evidence on BoNT-A immunoresistance in aesthetic and therapeutic applications and discussed best practices integrating clinical, ethical, and aesthetic considerations. Consensus statements relating to awareness, assessment, and management of the risk of NAb-related secondary nonresponse in aesthetic practice were developed.

Results

There was a consensus that, as doses used in aesthetic practice become like those in therapeutics, rates of NAb formation may be expected to increase. However, the true extent of NAb formation in aesthetics is likely underestimated due to limitations of published evidence and variability in treatment patterns of aesthetic patients. Since BoNT-A therapy is often lifelong, practitioners need to recognize immunogenicity as a potential complication that might affect future therapeutic use and strive to minimize modifiable risk factors. The selection and use of a BoNT-A product with the least immunogenic potential from the beginning may thus be advantageous, especially when treatment with high doses is planned.

Conclusions

In view of current trends in BoNT-A aesthetic use, it is essential for practitioners to conduct thorough clinical assessments, inform patients of treatment risks, and develop BoNT-A treatment plans to minimize immunogenicity. This can help preserve the option of continued or future BoNT-A treatment with satisfactory outcomes.

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 .

Botulinum Toxin A: A Review of Potential Uses in Treatment of Female Urogenital and Pelvic Floor Disorders

Background: Botulinum toxin is an injectable neuromodulator that inhibits transmission between peripheral nerve endings and muscle fibers, resulting in muscle paralysis. Botulinum toxin type A is the most common form of botulinum toxin used in clinical practice.

Methods: In this review, we examine the mechanism of action, formulations, common clinical use in the genital-urinary tract, and potential clinical use in pelvic floor disorders of botulinum toxin type A.

Results: Several aspects of botulinum toxin A make it a favorable therapeutic tool, including its accessibility, its longevity, and its impermanence and reversibility of resultant chemodenervation in a relatively short and safe manner. Although botulinum toxin A has well-established efficacy in treating refractory overactive bladder and neurogenic detrusor overactivity, its use in pelvic floor disorders is still in its infancy.

Conclusion: The efficacy of botulinum toxin A for treating pelvic pain, voiding dysfunction, muscle pain and dysfunction, and certain colorectal-related pain issues shows promise but requires additional rigorous evaluation.

Efficacy of botulinum toxin in the management of temporomandibular myofascial pain and sleep bruxism

Objectives

This study sought to evaluate the efficacy of injecting botulinum toxin into the masseter and temporal muscles in patients with temporomandibular myofascial pain and sleep bruxism.

Materials and Methods

The study was conducted based on a clinical record review of 44 patients (36 females and eight males; mean age, 35.70±12.66 years). Patients who underwent the injection of botulinum toxin into the masseter and temporal muscles for the management of temporomandibular myofascial pain and sleep bruxism were included in the study. Patients were diagnosed based on the Diagnostic Criteria for Temporomandibular Disorders. Sleep bruxism was diagnosed according to the criteria defined by the American Academy of Sleep Medicine. The values of the visual analogue scale (VAS) and range of jaw motion, including unassisted maximum mouth opening (MMO), protrusion, and right and left laterotrusion, were observed preoperatively and postoperatively at one-, three-, and six-month follow-up visits.

Results

MMO, movements of the right and the left laterotrusion, and protrusion increased significantly (P<0.05), while VAS ratings decreased significantly at the three follow-up points relative to baseline values (P<0.05).

Conclusion

Botulinum toxin is an effective treatment for patients with temporomandibular myofascial pain and sleep bruxism.

Antibody-induced botulinum toxin treatment failure: A review and novel management approach

BACKGROUND

Botulinum neurotoxin A (BoNT/A) has been used for cosmetic indications for many decades. Consumption of BoNT/A usage has been markedly increased for a few years. Even new formulations of BoNT/A to decrease immunogenicity have been released, repeated treatment to maintain efficacy outcome is inevitable and could finally provoke immune response. In the past, prevalence of botulinum treatment failure (BTF) in cosmetic indication was rare leading to less medical concern. Current decade, case reports on BTF, especially antibody-induced botulinum toxin treatment failure (ABTF), have been increasingly revealed and risk factors associated with ABTF have been intensively studied.

AIMS

In this article, we will review antibody-induced botulinum toxin treatment failure (ABTF), risk-associated ABTF, prevalence and recent case reports of ABTF, and new approach to deal with ABTF.

METHODS

Literature search was conducted using PubMed. The relevant literatures published between January 2000 and May 2020 concerning BTF and ABTF including investigation for ABTF were included and analyzed.

RESULTS

Possible causes of BTF were summarized. ABTF could be a tip of iceberg of BTF, its prevalence, and currently, 10-year case reports of ABTF were published evidence. Risk factors and investigation methods for ABTF were also summarized. Based on previous studies and our experience, novel approach to management of ABTF was described.

CONCLUSION

Effective management of BTF is to explore causes of treatment failure. Antibodies against BoNT/A complex could be one of many possibilities. Laboratory in vitro tests could be alternative tools to decrease adverse effect and rebooting immune responses in BTF patients.

The Use of Botulinum Neurotoxin Type A in Aesthetics: Key Clinical Postulates

BACKGROUND

The most common aesthetic procedure performed worldwide is the injection of botulinum neurotoxin Type A (BoNT-A). Aesthetic providers must fully comprehend the objective scientific data, theoretical mechanisms of action, and differences between brands of BoNT-A.

OBJECTIVE

To determine and review the relevant clinical postulates for the use of botulinum toxin in aesthetics.

MATERIALS AND METHODS

The BoNT-A clinical postulates presented here discuss how each brand of BoNT-A acts identically, how the molecular potency may vary between the different products, how patient age, gender, genetics, and muscle mass cause variation in toxin receptor number and density, and how both practitioner and patient can affect toxin distribution.

RESULTS

A total of 8 clinical postulates have been identified that are key to understanding the use of botulinum toxin in aesthetics and to obtaining the best clinical results.

CONCLUSION

All of these factors affect the potential efficacy of the injected toxin and hence the aesthetic results obtained.

Injectable and topical neurotoxins in dermatology: Indications, adverse events, and controversies

The use of neuromodulators for therapeutic and cosmetic indications has proven to be remarkably safe. While aesthetic and functional adverse events are uncommon, each anatomic region has its own set of risks of which the physician and patient must be aware before treatment. The therapeutic usages of botulinum toxins now include multiple specialties and multiple indications. New aesthetic indications have also developed, and there has been an increased utilization of combination therapies to combat the effects of global aging. In the second article in this continuing medical education series, we review the prevention and treatment of adverse events, therapeutic and novel aesthetic indications, controversies, and a brief overview of combination therapies.

Botulinum Neurotoxins: Biology, Pharmacology, and Toxicology

The study of botulinum neurotoxins (BoNT) is rapidly progressing in many aspects. Novel BoNTs are being discovered owing to next generation sequencing, but their biologic and pharmacological properties remain largely unknown. The molecular structure of the large protein complexes that the toxin forms with accessory proteins, which are included in some BoNT type A1 and B1 pharmacological preparations, have been determined. By far the largest effort has been dedicated to the testing and validation of BoNTs as therapeutic agents in an ever increasing number of applications, including pain therapy. BoNT type A1 has been also exploited in a variety of cosmetic treatments, alone or in combination with other agents, and this specific market has reached the size of the one dedicated to the treatment of medical syndromes. The pharmacological properties and mode of action of BoNTs have shed light on general principles of neuronal transport and protein-protein interactions and are stimulating basic science studies. Moreover, the wide array of BoNTs discovered and to be discovered and the production of recombinant BoNTs endowed with specific properties suggest novel uses in therapeutics with increasing disease/symptom specifity. These recent developments are reviewed here to provide an updated picture of the biologic mechanism of action of BoNTs, of their increasing use in pharmacology and in cosmetics, and of their toxicology.

Key Parameters for the Use of AbobotulinumtoxinA in Aesthetics: Onset and Duration

Time to onset of response and duration of response are key measures of botulinum toxin efficacy that have a considerable influence on patient satisfaction with aesthetic treatment. However, there is no overall accepted definition of efficacy for aesthetic uses of botulinumtoxinA (BoNT-A). Mechanical methods of assessment do not lend themselves to clinical practice and clinicians rely instead on assessment scales such as the Frontalis Activity Measurement Standard, Frontalis Rating Scale, Wrinkle Severity Scale, and Subject Global Assessment Scale, but not all of these have been fully validated. Onset of activity is typically seen within 5 days of injection, but has also been recorded within 12 hours with abobotulinumtoxinA. Duration of effect is more variable, and is influenced by parameters such as muscle mass (including the effects of age and sex) and type of product used. Even when larger muscles are treated with higher doses of BoNT-A, the duration of effect is still shorter than that for smaller muscles. Muscle injection technique, including dilution of the toxin, the volume of solution injected, and the positioning of the injections, can also have an important influence on onset and duration of activity. Comparison of the efficacy of different forms of BoNT-A must be made with the full understanding that the dosing units are not equivalent. Range of equivalence studies for abobotulinumtoxinA (Azzalure; Ipsen Limited, Slough UK/Galderma, Lausanne CH/Dysport, Ipsen Biopharm Limited, Wrexham UK/Galderma LP, Fort Worth, TX) and onabotulinumtoxinA (Botox; Allergan, Parsippany, NJ) have been conducted, and results indicate that the number of units of abobotulinumtoxinA needs to be approximately twice as high as that of onabotulinumtoxinA to achieve the same effect. An appreciation of the potential influence of all of the parameters that influence onset and duration of activity of BoNT-A, along with a thorough understanding of the anatomy of the face and potency of doses, are essential to tailoring treatment to individual patient needs and expectations.

Treatment of chronic pain associated with nocturnal bruxism with botulinum toxin. A prospective and randomized clinical study

Background

To evaluate the role of botulinum toxin type A (BTX-A) in the treatment of pain associated with nocturnal bruxism.

Material and Methods

Fifty subjects reporting nocturnal bruxism were recruited for a randomized clinical trial. Twenty five bruxers were injected with botulinum toxin in both masseters, and twenty five were treated with traditional methods of treating bruxism. Patients were evaluated at 3rd week, 2nd and 6th month and one year after injection and then used to calculate bruxism events. Bruxism symptoms were investigated using questionnaires.

Results

Mean pain score due to Bruxism events in the masseter muscle decreased significantly in the botulinum toxin injection group A (P =0.000, highly significant). However, in the conventional treatment group, mean pain score does not show improvement with time (p>0.05).

Conclusions

Our results suggest that botulinum toxin injection reduced the mean pain score and number of bruxism events, most likely by decreasing the muscle activity of masseter rather than affecting the central nervous system.

Key words:Temporomandibular pain, nocturnal bruxism, botulinum toxin.

Progress in cell based assays for botulinum neurotoxin detection

Botulinum neurotoxins (BoNTs) are the most potent human toxins known and the causative agent of botulism, and are widely used as valuable pharmaceuticals. The BoNTs are modular proteins consisting of a heavy chain and a light chain linked by a disulfide bond. Intoxication of neuronal cells by BoNTs is a multi-step process including specific cell binding, endocytosis, conformational change in the endosome, translocation of the enzymatic light chain into the cells cytosol, and SNARE target cleavage. The quantitative and reliable potency determination of fully functional BoNTs produced as active pharmaceutical ingredient (API) requires an assay that considers all steps in the intoxication pathway. The in vivo mouse bioassay has for years been the 'gold standard' assay used for this purpose, but it requires the use of large numbers of mice and thus causes associated costs and ethical concerns. Cell-based assays are currently the only in vitro alternative that detect fully functional BoNTs in a single assay and have been utilized for years for research purposes. Within the last 5 years, several cell-based BoNT detection assays have been developed that are able to quantitatively determine BoNT potency with similar or greater sensitivity than the mouse bioassay. These assays now offer an alternative method for BoNT potency determination. Such quantitative and reliable BoNT potency determination is a crucial step in basic research, in the development of pharmaceutical BoNTs, and in the quantitative detection of neutralizing antibodies.

Noncosmetic periocular therapeutic applications of botulinum toxin

Botulinum toxin blocks acetylcholine release at the neuromuscular junction. The drug which was initially found to be useful in the treatment of strabismus has been extremely effective in the treatment of variety of conditions, both cosmetic and noncosmetic. Some of the noncosmetic uses of botulinum toxin applications include treatment of spastic facial dystonias, temporary treatment of idiopathic or thyroid dysfunction-induced upper eyelid retraction, suppression of undesired hyperlacrimation, induction of temporary ptosis by chemodenervation in facial paralysis, and correction of lower eyelid spastic entropion. Additional periocular uses include control of synchronic eyelid and extraocular muscle movements after aberrant regeneration of cranial nerve palsies. Cosmetic effects of botulinum toxin were discovered accidentally during treatments of facial dystonias. Some of the emerging nonperiocular application for the drug includes treatment of hyperhidrosis, migraine, tension-type headaches, and paralytic spasticity. Some of the undesired side effects of periocular applications of botulinum toxin inlcude ecchymosis, rash, hematoma, headache, flu-like symptoms, nausea, dizziness, loss of facial expression, lower eyelid laxity, dermatochalasis, ectropion, epiphora, eyebrow and eyelid ptosis, lagophthalmos, keratitis sicca, and diplopia.

Effect of botulinum toxin injection on nocturnal bruxism: a randomized controlled trial

OBJECTIVE

To evaluate the effect of botulinum toxin type A on nocturnal bruxism.

DESIGN

Twelve subjects reporting nocturnal bruxism were recruited for a double-blind, randomized clinical trial. Six bruxers were injected with botulinum toxin in both masseters, and six with saline. Nocturnal electromyographic activity was recorded in the subject's natural sleeping environment from masseter and temporalis muscles before injection, and 4, 8, and 12 wks after injection and then used to calculate bruxism events. Bruxism symptoms were investigated using questionnaires.

RESULTS

Bruxism events in the masseter muscle decreased significantly in the botulinum toxin injection group (P = 0.027). In the temporalis muscle, bruxism events did not differ between groups or among times. Subjective bruxism symptoms decreased in both groups after injection (P < 0.001).

CONCLUSIONS

Our results suggest that botulinum toxin injection reduced the number of bruxism events, most likely mediated its effect through a decrease in muscle activity rather than the central nervous system. We controlled for placebo effects by randomizing the interventions between groups, obtaining subjective and objective outcome measures, using the temporalis muscle as a control, and collecting data at three postinjection times. Our controlled study supports the use of botulinum toxin injection as an effective treatment for nocturnal bruxism.

A neuronal cell-based botulinum neurotoxin assay for highly sensitive and specific detection of neutralizing serum antibodies

Clostridium botulinum neurotoxin (BoNT) serotypes A and B are widely used as pharmaceuticals to treat various neurological disorders and in cosmetic applications. The major adverse effect of these treatments has been resistance to treatment after multiple injections. Currently, patients receiving BoNT therapies and patients enrolled in clinical trials for new applications and/or new formulations of BoNTs are not routinely monitored for the formation of neutralizing antibodies, since no assay other than the mouse protection procedure is commercially available that reliably tests for the presence of such antibodies. This report presents a highly sensitive and specific neuronal cell-based assay that provides sensitive and specific detection of neutralizing antibodies to BoNT/A.