Botulinum Toxin Type Research Articles

Botulinum Toxin Type A (BoNT-A) Use for Post-Stroke Spasticity: A Multicenter Study Using Natural Language Processing and Machine Learning.

We conducted a multicenter and retrospective study to describe the use of botulinum toxin type A (BoNT-A) to treat post-stroke spasticity (PSS). Data were extracted from free-text in electronic health records (EHRs) in five Spanish hospitals. We included adults diagnosed with PSS between January 2015 and December 2019, stratified into BoNT-A-treated and untreated groups. We used EHRead® technology, which incorporates natural language processing and machine learning, as well as SNOMED CT terminology. We analyzed demographic data, stroke characteristics, BoNT-A use patterns, and other treatments. We reviewed the EHRs of 1,233,929 patients and identified 2190 people with PSS with a median age of 69 years; in total, 52.1% were men, 70.7% had cardiovascular risk factors, and 63.2% had suffered an ischemic stroke. Among the PSS patients, 25.5% received BoNT-A at least once. The median time from stroke to spasticity onset was 205 days, and the time from stroke to the first BoNT-A injection was 364 days. The primary goal of BoNT-A treatment was pain control. Among the study cohort, rehabilitation was the most common non-pharmacological treatment (95.5%). Only 3.3% had recorded monitoring scales. In conclusion, a quarter of patients with PSS received BoNT-A mainly for pain relief, typically one year after the stroke. Early treatment, disease monitoring, and better data documentation in EHRs are crucial to improve PSS patients' care.

Botulinum toxin type a (BOTOX) in the management of glossopharyngeal neuralgia- A case series

Glossopharyngeal neuralgia [GPN] is a rare, debilitating neurologic condition characterized by intermittent pain radiating to the tongue, pharynx or ear that can be triggered by talking, swallowing or chewing. With an incidence of only 0.2-0.7 persons/100,000/year, the diagnosis is extremely challenging and often gets misdiagnosed and undiagnosed. Many treatment options have been tried by various clinicians in the past, such as medical therapy (antidepressants, opiods, antiepileptics, steroids, and membrane-stabilizing agents), nerve blocks with or without additives, gamma knife radiosurgery, radiofrequency ablation and microvascular decompression. Each of the aforementioned treatment modalities has its own merits and limitations. In the pursuit of delivering optimal treatment for pain relief in GPN and to improve patient's quality of life, we have explored the use of Botulinum toxin type A [BOTOX (Allegran®)]. BOTOX has been widely used in the treatment of chronic facial pain such as headaches, migraine, and trigeminal neuralgia. However, the use of BOTOX in the management of GPN has not been reported in the literature. Despite the small number of cases in our series, BOTOX therapy in GPN appears to be promising. However, further research with larger sample sizes and longer follow-up periods is needed to fully establish its efficacy and safety profile

Contouring With Neuromodulators.

Botulinum toxins, originally used for facial rejuvenation, have emerged as a promising tool for sculpting and refining contours for both the face and body. The peer-reviewed literature on neuromodulator contouring treatments was analyzed, with a particular emphasis on studies and case reports involving the use of botulinum toxin type A. Modification of face, neck, shoulder, arm, and calf contour has been reported. Treatment and dosing protocols vary with the strength and depth of the target muscle. Regional effects of neuromodulator treatment begin to appear approximately 2 weeks after injection and are often most prominent at the 70- to 90-day time point. Although treatments are generally well tolerated, short-term muscle weakness and other side effects may occur. The use of neuromodulators to enhance facial and body contours has demonstrated efficacy, but further research is needed to validate their use and explore the full potential of this intervention through larger randomized controlled trials. The application of neuromodulators as a minimally invasive tool to address the rising demand for nonsurgical body sculpting represents a promising frontier in aesthetics.

Comparing the efficacy, safety, and satisfaction for moderate to severe glabellar frown lines between abobotulinum toxin A and incobotulinum toxin A: a multicenter randomized study

Background Botulinum toxin type A is widely used to improve facial wrinkles associated with aging, and various types are available. However, the efficacy, particularly the duration of effect, varies among these types, and research on this subject is limited. This study aimed to compare the efficacy and safety of incobotulinum toxin A and abobotulinum toxin A.Methods This prospective analysis included cases of moderate to severe glabellar lines treated with either incobotulinum toxin A or abobotulinum toxin A. After a 24-week follow-up, clinical photos were taken at each visit. The severity of the glabellar lines was evaluated by three groups: the investigator, the patients, and an independent evaluator.Results The study included a total of 42 patients. When comparing the improvement rates of glabellar lines at maximum frown for both groups at the week-4 visit, which was the primary efficacy endpoint, no statistically significant difference was observed. However, the abobotulinum toxin A group demonstrated a higher improvement at the week-24 visit, as evaluated by the investigator, and this difference was statistically significant.Conclusions Overall, the abobotulinum toxin A group exhibited a higher improvement rate in the glabellar lines at the frown state. The difference in the improvement rate at the week-24 visit was 36.86%, which was statistically significant.

Neurotoxins and Combination Therapies.

Facial aging involves multilevel changes, extending from the skin to deep support structures. A comprehensive treatment approach targeting the many aspects of facial dynamics and architecture is often necessary to achieve optimal correction, prevent changes before they occur, and/or help highlight inherited features. To explore the integration of botulinum toxin type A (BoNT-A) into multimodal aesthetic treatment plans. This article reviews evidence supporting the combination of BoNT-A with other minimally invasive cosmetic therapies, including dermal fillers, lasers, and energy-based devices as well as with plastic and reconstructive surgeries for more controlled healing and improved scar cosmesis. Combination treatment protocols including BoNT-A demonstrate higher patient satisfaction and retention rates compared to monotherapy or sequential treatments. Some guidelines for sequencing of treatments exist, but evidence is scant with certain combinations. Integrating BoNT-A into a larger aesthetic treatment plan is crucial for achieving natural and satisfying results in facial rejuvenation. Evidence supports better outcomes when incorporating with both surgical and nonsurgical modalities. Understanding how to address anatomy over time through different aesthetic therapies together allows for individually tailored, more deeply impactful treatment plans.

Is Botulinum Toxin Type A Safe for Gummy Smile Treatment in Bronchial Asthma Patients? A Case Report

Background and Aim: The increasing demand for aesthetic enhancements has led to the widespread use of Botox for various facial concerns, including gummy smiles. While its efficacy in treating gummy smiles is established, the safety profile of Botox in patients with underlying medical conditions, such as asthma, remains relatively unexplored. This case report presents a patient with asthma who underwent Botox treatment to correct excessive gingival display. The study aims to demonstrate the potential of Botox for aesthetic improvement in this patient population while emphasizing the need for further research to assess its safety profile. Results: A two-week Botox treatment course successfully eliminated the patient's gummy smile without inducing any asthma-related complications or adverse effects. Conclusion: Although this case suggests the potential of Botox for treating gummy smiles in patients with asthma, it is essential to conduct larger studies to establish its safety and efficacy. A comprehensive medical evaluation is crucial before considering Botox treatment for individuals with underlying health conditions.

Temporary Delayed Hypersensitivity Reaction to Botulinum Toxin-A After COVID-19 Vaccination: A Case Series.

The occurrence of a hypersensitivity reaction with the injection of botulinum toxin type A (BTX-A) in cosmetic use is a rare complication. We report the largest case series of temporary delayed hypersensitivity reaction (DHR) with BTX-A following COVID-19 vaccination and the first cases to incobotulinum toxin A (incoBTX-A). A retrospective multicentric case series of patients who developed a DHR to BTX-A after COVID-19 vaccination. Twelve patients were treated with BTX-A injections for the management of facial rhytids. The age range was between 29 and 45years. Ten (83.3%) were female. Ten (83.3%) patients received incoBTX-A, and two received onabotulinum toxin A (onaBTX-A). All patients had COVID-19 vaccination (mRNA vaccine) between 1 and 7months before. Within an average time of 24h after BTX-A injection, all patients developed progressive facial swelling and erythema that were more prominent at the injection points. Intradermal allergic tests to BTX-A were performed in six (50%) patients, and the results were all negative. Adequate clinical control was achieved with systemic corticosteroids and antihistamines. After 1year with no further vaccination, a new BTX-A treatment (provocation test) was performed in all patients with no secondary effects. Previous COVID-19 vaccination and the absence of new adverse events with further BTX-A injections suggest a temporary DHR. Clinicians should be aware of the importance of immunization history and its potential post-vaccine immunogenic effects with BTX-A. 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 .

IncobotulinumtoxinA for Aesthetic Treatments: Review and Recommendations From Latin America.

As new aesthetic treatment techniques are developed, the understanding of botulinum toxin type A safety and treatment outcomes continues to evolve. This article was developed to provide a comprehensive up-to-date reference for clinicians using incobotulinumtoxinA (INCO; Xeomin/Bocouture, Merz Pharmaceuticals GmbH, Frankfurt, Germany) for aesthetic treatments. A Latin American panel of 11 physicians was assembled to discuss and develop recommendations on the use of INCO for aesthetic treatment based on the literature review and their private medical practice. The panel found that INCO is a highly purified botulinum toxin, without other clostridial proteins (hemagglutinins and nonhemagglutinins). IncobotulinumtoxinA has proven its efficacy and duration over time, maintaining response after multiple treatment cycles. This recommendation provides up-to-date information on the use of INCO for aesthetic treatment, focusing on the differential properties of this product regarding its purity, performance, customization, and patient satisfaction.

Botulinum toxin combined with static progressive stretching improves fibrous stiffness of knee joint in rats through TGF-β1/Smad pathway.

Joint stiffness and fibrosis are common complications that affect mobility and quality of life, necessitating effective therapeutic strategies to alleviate these issues. The study aimed to observe the therapeutic effect of static progressive stretching (SPS) combined with botulinum toxin type A (BTX-A) on knee joint stiffness in rats and its effect on the transforming growth factor beta 1 (TGF-β1)/small mother against decapentaplegic (Smad) pathway in the development of joint capsule fibrosis. Forty Sprague Dawley rats were randomly divided into the blank control group, model control group, SPS intervention group, BTX-A intervention group, and SPS combined with BTX-A intervention group. Except for the blank control group, the right knee joints of the other rats were surgically fixed with Kirschner wire internal immobilization in full flexion for four weeks to form joint flexion contracture and cause fibrotic stiffness of the joint. The therapeutic effect of each intervention was assessed by the range of motion (ROM) of the knee joint, joint stiffness, the number of total cells, and collagen deposition in the posterior joint capsule, as well as the protein level expressions of TGF-β1, Smad2, Smad3, Smad4, p-Smad2/3, collagen I and III, and alpha smooth muscle actin (α-SMA) in the posterior joint capsule in the TGF-β1/Smad pathway. SPS combined with BTX-A was more effective in relieving joint fibrosis stiffness, improving the histopathological changes in the posterior joint capsule, and suppressing the high expression of target proteins and the overactivated TGF-β1/Smad pathway. The overactivated TGF-β1/Smad pathway was involved in the formation of knee joint fibrosis stiffness in rats. SPS combined with BTX-A was effective in relieving joint flexion contracture and fibrosis of the joint capsule. Moreover, the inhibition of the overactivated TGF-β1/Smad pathway may be the potential molecular mechanism for its therapeutic effect.

A preliminary study on ultrasound techniques applied to evaluate the curative effect of botulinum toxin type a in hypertrophic scars

ObjectiveTo validate the feasibility of ultrasound in assessing the curative effect of botulinum toxin type A (BTXA) in treating hypertrophic scar (HS). MethodsEight healthy New Zealand long-eared rabbits were utilized in the study. Four wounds, each measuring 1.0 cm in diameter, were created on both ears of each rabbit. Immediately after surgery, each of these wounds received an injection containing a distinct concentration of BTXA. On postoperative week 6, scar thickness, vascularity, and hardness were assessed based on high frequency ultrasound (HFUS), superb microvascular imaging (SMI), shear wave elastography (SWE), Masson staining, and immunohistochemical staining for CD31. ResultsAll wounds healed well, and HSs formed after 6 weeks post-surgery. Scar thickness based on HFUS presented a significant decrease with increasing BTXA concentration (p < 0.05), aligning with the gross morphology. Simultaneously, scar stiffness, evaluated using SWE, showed a significant decrease in accordance with the variation of the collagen volume fraction, which refers to the ratio of the collagen positive area to the total area (p < 0.05). Although the vascularity index obtained by SMI did not exhibit a statistically significant change across different BTXA concentrations, this technique effectively illustrated the microvascular perfusion in HS. Immunohistochemical staining for CD31 revealed that BTXA inhibited angiogenesis. ConclusionHFUS and SWE displayed excellent performance in evaluating HS thickness and stiffness. SMI showed a good performance in reflecting microvascular signals in HS. These ultrasound techniques have great potential in assessing the therapeutic effect of BTXA in HS.

Comparison between botulinum toxin type A injection on masseter muscle only and additional injection on anterior belly of digastric muscle in sleep bruxism patients: A clinical trial.

This study aims to evaluate the effects on bite force and muscle thickness of the botulinum toxin (BoNT) injection for patients with sleep bruxism (SB) by comparing injections into the masseter muscle only and both the masseter and the anterior belly of the digastric muscle (ABDM) in a clinical trial. Twelve SB patients received BoNT-A injections using US-guided techniques into the masseter muscle only (Group A), while the remaining 12 SB patients received injections into both the masseter and ABDM (Group B). Bite force and muscle thickness were measured before injection, as well as 1 and 2 months after injection. The bite force and masseter muscle thickness decreased in both Group A and Group B before injection, and at 1 and 2 months after injection. However, there was no significant difference (p > .05, repeated measures analysis of variance) between the two groups, and there was also no significant difference in ABDM thickness (p > .05, repeated measures analysis of variance). This study is the first to assess the short-term effects of BoNT injected into ABDM for SB control. Results show no influence on SB reduction, suggesting the need for further research on BoNT's effectiveness in controlling intense ABDM contractions during sleep and assessing suprahyoid muscle potential impact on rhythmic masticatory muscle activity occurrence.

Neuromodulators in Men.

Botulinum toxin treatment is gaining popularity among men for cosmetic purposes driven by workplace competition and a desire for confidence and youthfulness. Because of the unique features of male facial anatomy, careful consideration is necessary during assessment and treatment execution. The peer-reviewed literature on male facial anatomy in relation to neuromodulator treatment was analyzed with a particular emphasis on studies involving male subjects and the use of botulinum toxin type A. Anatomic differences in muscle mass and contraction patterns between men and women help guide treatment. Men appear to require higher doses for effective treatment of facial wrinkles and, in the case of glabellar lines, often require double the standard dose for women. Treatment of the frontalis muscle in men, responsible for forehead creases, requires precise dosage and placement to avoid brow ptosis. The lateral canthal wrinkles are often the first area that men seek consultation for. Although FDA approval for lower face regions is lacking, off-label use can still be considered. Successful botulinum toxin treatment in men necessitates understanding facial anatomy, customized treatment plans, and appropriate dosing. Further research is warranted to refine protocols and enhance outcomes for male patients.

Adverse events related to botulinum toxin type A, reported in Brazil between 2019 and 2022

The International Society of Aesthetic Plastic Surgery estimates that 18,857,311 non-invasive aesthetic procedures were carried out worldwide in 2022. This represents an increase of 7.2% compared to 2021 and 57.8% compared to 2018. Brazil is the second country in the world, just behind the United States, in the number of aesthetic procedures, with 3,020,552. Of these, 971,294 were non-invasive, with the administration of botulinum toxin, at 433,263, being the most frequent procedure. In aesthetics, it is used for the treatment of facial asymmetries, expression lines, hyperhidrosis in the hands, feet, armpits, face, and inguinal region, and in the treatment of gummy smile, attenuation of forehead wrinkles, perioral wrinkles, mental creases, glabellar lines, periorbital wrinkles, nasal wrinkles, wrinkles found on the décolletage, nasal tip stabilization, drooping lips, eyebrow lifting, and platysma bands. The most common adverse reactions associated with the use of botulinum toxin are burning, pain, swelling, irritation at the application sites, hypersensitivity, anaphylaxis in extreme cases, blurred vision, dry mouth, rarely respiratory failure, and muscle weakness. The objective of the study was to describe the adverse events (AEs) reported in the Vigimed system between 2019 and 2022. In the period analyzed, only 50 possible AEs were reported, with the female gender and the age group of 18 to 44 years being the most frequent. The pharmaceutical industry was responsible for 82% of the notifications analyzed, however, when evaluating the reporting professional, it was observed that pharmacists reported in only 8% of the cases. When evaluating the most reported AEs, swelling and pain were the most frequent, at 30% and 24% respectively. The underreporting of these events and the need for public and private incentives to raise awareness among health professionals and users about the need for identification and reporting of AEs is clear.

Treatment of Primary Axillary Hyperhidrosis with Two Doses of Botulinum Toxin A-Observational Study.

Hyperhidrosis (HH) is defined as the production of more sweat than is necessary for its thermoregulatory function, negatively affecting patients' quality of life and interfering with their social, work and family life. In this context, the aim of thisstudy was to evaluate the efficacy of two different doses of botulinum toxin type A (50 or 100 units) in each axilla in severe primary axillary hyperhidrosis. A descriptive, observational, cross-sectional and post-authorisation study was conducted onpatients referred to our department.Thirty-one patients with severe primary axillary hyperhidrosis were included, some of whom received more than one infiltration during the follow-up period, performing a total of 82 procedures. They were assigned by simple random sampling to two types of treatment: infiltration of 50 or 100 units (U) of botulinum toxin A per axilla.Hyperhidrosis severity was assessed using the Hyperhidrosis Disease Severity Scale (HDSS), and quality of life was assessed using the Dermatology Life Quality Index (DLQI) questionnaire. Onabotulinum toxin A infiltration reduced the severity of hyperhidrosis and improved the quality of life of the treated patients, with no significant differences between the two groups.

The Use of Botulinum Toxin for Nasal Esthetics: A Systematic Review.

Physical attractiveness is commonly evaluated based on facial appearance, with the nose being the most noticeable feature. Botulinum toxin injection is a less invasive method for enhancing nasal esthetics, which can address minor nasal imperfections through relaxing muscles. To fully understand the uses of botulinum toxin in the nose area, a thorough review of the available information is necessary. We aimed to conduct a systematic review of literature to evaluate the effects and clinical application of botulinum toxin for nasal esthetics. We searched PubMed, Scopus, Google Scholar, and the Cochrane Central Register of Controlled Trials (CENTRAL) databases up until May 2023 to identify studies investigating the use of botulinum toxin for cosmetic enhancement in the nose area. Data was extracted from the selected studies regarding the baseline characteristics, type of botulinum toxin used, dosage, injection site, and outcomes. Initially, 1139 articles were found and 23 articles were included. The studies showed the usage of botulinum toxin can correct drooping nasal tips, dilated nostrils, minor post-rhinoplasty deformities, and high columellar show. It can also augment nasal dorsum, improve cleft lip-related deformities, and address other disorders related to the function and appearance of the nose. Botulinum toxin injection seems to be a safe and effective treatment option for individuals seeking to correct minor nasal defects. Further large-scale studies are recommended.

Response to Botulinum Toxin Type-A in Patients with Refractory Chronic Migraine

Background: Due to its debilitating nature, refractory chronic migraine (RCM) is primarily associated with a poor quality of life. However, controversy remains regarding the efficacy and safety of botulinum toxin for treating RCM. Objectives: The aim of this study was to investigate the efficacy of botulinum toxin type A (BTX-A) in patients with RCM. Methods: In this retrospective cross-sectional study conducted between April 2016 and March 2021, RCM patients who were resistant to conventional therapies and received BTX-A injections were followed for 7 and 14 days after the injection. The outcome variables included the frequency, duration, and severity of migraine episodes, the need for painkillers, adverse events, and the patient's perceived improvement. Data were analyzed using SPSS. Results: In total, 52 RCM patients with a mean age of 31.84 years participated, of whom 69.2% were female. The frequency of migraine episodes decreased from a baseline of 9.84 to 3.94 and 1.25 at 7 and 14 days after injection, respectively (P &lt; 0.001). The duration of migraine episodes dropped from 3 hours at baseline to 1.74 and 1.17 hours at 7 and 14 days post-BTX-A injection, respectively (P &lt; 0.001). The severity of migraines alleviated from 8.07 at baseline to 6.48 and 3.38 at the respective follow-up times (P &lt; 0.001). The need for painkillers also decreased at follow-ups (P &lt; 0.001). Males achieved better treatment outcomes regarding the frequency of migraine episodes and the need for medications compared to females following BTX-A treatment (P &lt; 0.05). Frontotemporal and frontotemporal-occipital headache distributions showed fewer migraine episodes, shorter duration, less severity, and lower need for painkiller consumption compared to other migraine types (P &lt; 0.05). The most common adverse event was localized pain (42.3%), followed by itching (25.0%). A considerable number of patients felt improvement. Conclusions: According to our findings, BTX-A is a safe and well-tolerated treatment for patients with RCM. Validation of these results requires adequately precise studies investigating the effect of BTX-A in detail.

Treatment of masseter muscle hypertrophy with botulinum toxin type A injection: A review of adverse events.

The popularity of noninvasive botulinum toxin type A (BTX-A) injections for masseter muscle hypertrophy is increasing among Asian individuals with a square-shaped lower face. This study aimed to analyze the adverse events (AEs) caused by BTX-A injections into the masseter muscle. This observational study retrospectively evaluated 46 250 patients who underwent BTX-A injections into the masseter muscle in 2022. The inclusion criteria were the diagnosis of an AE by the physician at the return visit and subsequent follow-up of progress (n = 223). The patients who were lost to follow-up (n = 40) were excluded from the study. Among the 223 patients with AEs, the most common AE was paradoxical bulging (88.3%, n = 197/223). The average period from treatment until confirmation of improvement was 159.6 ± 113.6 days (range 13-667 days) for all AEs, all of which were temporary. The period until improvement was 166.1 days in the intervention group (n = 122) and 151.9 days in the observation group (n = 101) (p = 0.24). As the period until improvement of AEs included the period until the patients visited the clinics and the improvements were confirmed by physicians, the actual period was likely to have been shorter. (1) All AEs were temporary. (2) All AEs improved within 22.2 months (within 5.3 ± 3.8 months on average). (3) There was no significant difference between the intervention and observation groups in the period until the improvement of AEs.

Clinical benefit of botulinum toxin for treatment of persistent TMD-related myofascial pain: A randomized, placebo-controlled, cross-over trial.

Injections of botulinum toxin type A (BoNT-A) have been proposed as an additional treatment modality for patients suffering chronic temporomandibular disorder (TMD)-related myofascial pain (MFP). BoNT-A impairs muscle function, along with its analgesic effect, and a minimal effective dose should be used. The objective of this randomized placebo-controlled crossover study was to evaluate the clinical benefit of a moderate dose (50 U) of BoNT-A. Sixty-six subjects were randomized into two groups, one which received BoNT-A first and a second which received a saline solution (SS) first. Follow-ups were performed 2, 11, and 16 weeks after the injections. Diagnostic criteria for temporomandibular disorders (DC/TMD) diagnostic algorithms were used to evaluate characteristic pain intensity (CPI) and pain-related disability based on the Graded Chronic Pain Scale (GCPS). Electromyographic and bite force were also evaluated. The within-group analysis showed a significant improvement in pain intensity and pain-related disability after BoNT-A (p < 0.001, p = 0.005, p = 0.011) and SS (p = 0.003, p = 0.005, p = 0.046) injections up to week 16. The between-group analysis of pain-related variables revealed no differences between groups at any time. Nonetheless, BoNT-A, but not SS, caused a significant decline in muscle performance. The number needed to treat (NNT) regarding a clinically significant pain reduction (≥30%) was 6.3, 57.0, and 19.0 at 2, 11, and 16-week follow-ups favoring BoNT-A. Injections of 50 U of BoNT-A might improve MFP symptoms, but the specific effect of the drug on pain compared to the placebo is not obvious.

Botulinum Toxin in Treatments for Abnormal Movements

Introduction: Botulinum toxin is crucial for reducing sequelae in movement disorders such as Parkinson's. It blocks muscle contractions and improves quality of life, being used in both aesthetic and medical treatments. Methodology: A non-experimental longitudinal design was adopted, observing variables at multiple time points without manipulation. A mixed approach (qualitative and quantitative) was used with adults over 30 years old without Parkinson's history. The review included documents from PubMed, Scopus, and Scielo, applying rigorous inclusion and exclusion criteria. Objective: To evaluate the efficacy of botulinum toxin in treating abnormal movements in Parkinson's and understand its long-term effects. Results: Botulinum toxin type A reduces tremors by blocking acetylcholine. It improves motor symptoms of Parkinson's and essential tremor but requires frequent and costly treatments. There is a risk of developing antibodies that decrease its effectiveness. Discussion: It offers significant benefits, but its high cost and the need for frequent treatments are challenges. Patients report satisfaction in short-term studies, but more long-term research is needed. Conclusions: Promising for movement disorders, especially Parkinson's, although limited by cost and duration of effect. Future research should seek to extend therapeutic effects and reduce costs.

Noninvasive analysis of overactive muscle structure and elasticity after botulinum toxin type A injection: a systematic review and meta-analysis.

Injections of botulinum toxin type A (BoNT-A) are the first-line treatment for spastic muscle overactivity (MO). Some authors observed that BoNT-A injections lead to changes in muscle structure and muscle elasticity that are probably not completely reversible. This possible effect is critical, as it could lead to negative impacts on the effectiveness of BoNT-A interventions. Our study aimed to evaluate the current literature regarding changes in muscle elasticity and structure after BoNT-A injection, by diagnostic imaging, in neurological populations with MO. Our second objective was to pool all articles published on this topic in order to provide a quantitative synthesis of the data. A systematic search was conducted between October 2021 and April 2023 using different databases in accordance with PRISMA guidelines. Two independent reviewers screened articles for inclusion, extracted data, and evaluated methodological quality of the studies. A meta-analysis was performed to compare muscle elasticity and structure before and after BoNT-A injections. A sample of 34 studies was selected for qualitative review and 19 studies for quantitative review. Meta-analysis of pre-post studies demonstrated significant improvement with a medium effect size (standardized mean difference=0.74; 95% CI 0.46-1.02; P<0.001) of muscle elasticity assessed by ultrasound elastography (USE) 4 weeks after BoNT-A injection. No statistically significant difference was found for muscle thickness, pennation angle, and muscle echo-intensity assessed by magnetic resonance imaging and/or ultrasonography at short-term. On the other hand, normalized muscle volume decreased with a small effect size (standardized mean difference = -0.17; 95% CI -0.25 - -0.09; P<0.001) 6 months after BoNT-A injection. Muscle elasticity measured by USE improves with a temporary effect at short-term following BoNT-A injections. Synthesis of studies that assesses muscle structure is hindered by methodological differences between studies. However, based on a small amount of data, normalized muscle volume seems to decrease at long-term after BoNT-A injections in children with CP suggesting that the timing of re-injection should be considered with caution in this population. Further work should focus on the long-term effect of repeated injections on muscle structure and elasticity in neurological populations.