Botulinum toxin type A for the management of glabellar rhytids

Adverse effect of botulinum toxin-A injections on mandibular bone: A systematic review and meta-analysis

INTRODUCTION

Botulinum toxin-A (BTX) is a potent neurotoxin that is emerging in the scope of dental practice for its ability to temporarily paralyse musculature and reduce hyperfunction. This may be desirable in diseases/disorders associated with hyperactive muscles such as the muscles of mastication, most implicated in painful temporomandibular disorders (TMDs). The use of BTX extends beyond its indications with off-label use in TMD's and other conditions, while potential adverse effects remain understudied. BTX is well-established hindlimb paralysis model in animals leading to significant bone loss with underlying mechanisms remaining unclear. The objective of this study is to systematically review the literature for articles investigating changes in mandibular bone following BTX injections and meta-analyse available data on reported bone outcomes.

METHODS

Comprehensive search of Medline, Embase and Web of Science retrieved 934 articles. Following the screening process, 36 articles in animals and humans were included for quantitative synthesis. Articles in human individuals (6) and three different animal species (14) presented mandibular bone outcomes that were included in the meta-analysis.

RESULTS

The masseter and temporalis muscles were frequently injected across all species. In humans, we observe a decrease of about 6% in cortical thickness of mandibular regions following BTX injection with no evident changes in either volume or density of bone structures. In animals, bone loss in the condylar region is significantly high in both cortical and trabecular compartments.

DISCUSSION

Our analysis supports the concept of BTX-induced bone-loss model in animal mandibles. Further, bone loss might be confined to the cortical compartments in humans. Most studies did not address the reality of repeated injections and excessive dosing, which occur due to the reversible action of BTX. More rigorous trials are needed to draw a full picture of potential long-term adverse effects on bone.

Effects of glabellar botulinum toxin injections on resting-state functional connectivity in borderline personality disorder

Meta-analyses suggest a sustained alleviation of depressive symptoms through glabellar botulinum toxin (BTX) injections. This can be explained by the disruption of facial feedback loops, which may moderate and reinforce the experience of negative emotions. Borderline personality disorder (BPD) is characterized by excessive negative emotions. Here, a seed-based resting-state functional connectivity (rsFC) analysis following BTX (N = 24) or acupuncture (ACU, N = 21) treatment in BPD is presented on areas related to the motor system and emotion processing. RsFC in BPD using a seed-based approach was analyzed. MRI data were measured before and 4 weeks after treatment. Based on previous research, the rsFC focus was on limbic and motor areas as well as the salience and default mode network. Clinically, after 4 weeks both groups showed a reduction of borderline symptoms. However, the anterior cingulate cortex (ACC) and the face area in the primary motor cortex (M1) displayed aberrant rsFC after BTX compared to ACU treatment. The M1 showed higher rsFC to the ACC after BTX treatment compared to ACU treatment. In addition, the ACC displayed an increased connectivity to the M1 as well as a decrease to the right cerebellum. This study shows first evidence for BTX-specific effects in the motor face region and the ACC. The observed effects of BTX on rsFC to areas are related to motor behavior. Since symptom improvement did not differ between the two groups, a BTX-specific effect seems plausible rather than a general therapeutic effect.

Botulinum toxin for the management of depression: An updated review of the evidence and meta-analysis

Botulinum toxin (BTX) treatment of glabellar frown lines is one of the most common procedures in aesthetic medicine. In addition to its cosmetic effect, the neurotoxin has been shown to have a positive influence on mood and affect. Several randomized clinical trials (RCTs) have examined the effect of botulinum toxin on the treatment of depression. Combining the results of the five RCTs in a random effects meta-analysis revealed that patients treated with BTX showed a more intense improvement of depressive symptoms in comparison to subjects that received placebo injections (d = 0.98). Despite methodological limitations, the results of this study emphasize the effectiveness of BTX in the treatment of depression and therefore pave the way for its use in the field of psychiatry.

Effects of botulinum toxin A on endometriosis‑associated pain and its related mechanism

Endometriosis (EMS) is a common disease in women aged 25–45 years, and pain is the main clinical symptom. The primary clinical treatment is surgical excision and drug therapy targeting the ectopic lesions, but these have not been very effective. Botulinum neurotoxin serotype A (BTX-A) has been reported to be useful in the treatment of pain in a variety of diseases. Based on this, the aim of the present study was to explore the therapeutic effect and mechanism of BTX-A on EMS. A model of nerve injury induced by oxygen glucose deprivation (OGD) was constructed in PC12 cells and EMS mice. Model cells and mice were treated with different concentrations of BTX-A to observe the changes in pain behavior, to detect cell viability and the secretion of norepinephrine (NE) and methionine enkephalin (M-EK) in cells and the spinal cord, and to evaluate the expression of apoptosis-related molecules in spinal cord nerves. The results revealed that BTX-A significantly reduced the amount of writhing in model mice, enhanced the activity of PC12 OGD cells, increased the secretion of NE and M-EK in model cells and the spinal cord of mice, and decreased the apoptosis of neural cells in the spinal cord of the model mice. Therefore, it was hypothesized that BTX-A may alleviate the pain induced by EMS by increasing the secretion of analgesic substances and promoting the repair of nerve injury. The present study provided a theoretical basis for the treatment of pain induced by EMS.

Does Blocking Facial Feedback Via Botulinum Toxin Injections Decrease Depression? A Critical Review and Meta-Analysis

Researchers have proposed that blocking facial feedback via glabellar-region botulinum toxin injections (GBTX) can reduce depression. Random-effects meta-analyses of studies that administered GBTX to individuals with depression indicate that, 6 weeks postintervention, GBTX groups were significantly less depressed compared to placebo groups ( d = 0.83) and pretreatment levels ( d = 1.57). However, we noted the following concerns: (a) effect sizes were extraordinarily large, (b) authors failed to provide information to compute 51% of relevant effect sizes, (c) 96% of effect sizes came from studies conducted by investigators with conflicts of interest, (d) there is some evidence of publication bias, and (e) studies used ineffective blinding procedures. These considerations suggest that confidence in GBTX as a treatment for depression is premature.

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.

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.

Mechanism of motor coordination of masseter and temporalis muscles for increased masticatory efficiency in mice

The demand for the use of mice as animal models for elucidating the pathophysiologies and pathogeneses of oral motor disorders has been increasing in recent years, as more and more kinds of genetically modified mice that express functional disorders of the stomatognathic system become available. However, the fundamental characteristics of mouse jaw movements during mastication have yet to be fully elucidated. The purpose of this study was to investigate the roles of the masseter and temporalis muscles, and the mechanisms of motor coordination of these muscles for increasing masticatory efficiency in the closing phase in mice. Twenty-two male Jcl:ICR mice were divided into control (n = 8), masseter-hypofunction (n = 7) and temporalis-hypofunction groups (n = 7). Botulinum neurotoxin type A (BoNT⁄A) was used to induce muscle hypofunction. The masticatory movement path in the horizontal direction during the occlusal phase became unstable after BoNT⁄A injection into the masseter muscle. BoNT⁄A injection into the temporalis muscle decreased antero-posterior excursion of the late-closing phase corresponding to the power phase of the chewing cycle. These results suggest that the masseter plays an important role in stabilizing the grinding path, where the food bolus is ground by sliding the posterior teeth from back to front during the occlusal phase. The temporalis plays a major role in retracting the mandible more posteriorly in the early phase of closing, extending the grinding path. Masticatory efficiency is thus increased based on the coordination of activities by the masseter and temporalis muscles.

The Dilution Confusion: Easy Dosing for Botulinum Toxins

Aesthetic practitioners prefer various reconstitution volumes for botulinum toxins (BoNTAs). Some injectors prefer larger volumes of bacteriostatic normal saline (NaCl) to achieve a larger diffusion in certain areas and a smaller volume for more precise administration of the BoNTA. Some practitioners believe dilution volumes do not matter at all in relation to spread or diffusion, asserting the diffusion area is simply dose-related. It can get confusing when there is more than one injector in an office, different volumes of saline, and more than one type of syringe to administer the neurotoxin. This leaves possibilities for confusion and dosage errors. This article explores four steps to take the confusion out of reconstituting BoNTAs and delivering accurate and consistent doses within a medical office.

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.

Effectiveness of botulinum toxin (type-A) administered by the fixed-site dosing approach versus the muscle area identification

INTRODUCTION

Botulinum toxin is widely used in glabellar musculature. The authors express the need to individualize the approach by means of muscular identification to improve effectiveness. Despite these guidelines, the fixed-point technique is still used.

OBJECTIVE

Comparison of effectiveness of botulinum toxin administration in the glabellar zone by using fixed-site application versus objective-muscle-identification.

MATERIALS AND METHODS

Prolective dynamic cohort study. Patients (after previous informed consent) were assessed on their facial expressions, level of satisfaction, re-interventions, adverse effects, dosage, dilution, and number of injections. All patients who experienced either of both techniques of botulinum toxin administration (fixed-site or objective-muscle-identification) were subjected to followup by the following parameters: statistical analysis: student's t Test (inter-group mean comparisons), paired student's t test (intra-group mean comparisons), χ (2) with Fisher exact text.

RESULTS

Sixty-two patients were evaluated (31 fixed-site approach, 31 objective-muscle-identification). No patient abandoned the trial during followup. Fixed-site injections required larger doses (16 vs 12 U, p = 0.001), greater volume (0.48 vs. 0.37 ml, p = 0.001), and more application sites (4 vs 2, p = 0.001), compared to the objective-muscle-identification approach. Under the objective-muscle-identification technique, facial expressions were better attenuated (52 vs 65%, p = 0.001), with a higher initial satisfaction level (6 vs 9, p = 0.001) and final satisfaction level (9 vs 9.9, p = 0.001).

CONCLUSIONS

Botulinum toxin application is more effective when administered through the objective-muscle-identification approach (less frowning, lower doses, less fixed sites injected, and patients more satisfied at the end).

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.

Central nervous system toxicity after botulinum neurotoxin injection

Since Its first description of botulism toxicity in 1820s, specific formulations of botulinum neurotoxin (BoNT) have been introduced with different clinical benefits. However, there is increasing number of adverse events reported to Food and Drug Administration. This report presents the case of 62-year-old woman with Parkinson’s disease who received BoNT injections to treat painful spasticity in her hands. She developed severe generalized dystonia shortly after BoNT injections.