Botulinum Toxin Treatment Research Articles

The Efficacy of Botulinum Toxin A Injection in Pelvic Floor Muscles in Chronic Pelvic Pain Patients: A Double-Blinded Randomised Controlled Trial.

To evaluate and compare the efficacy and safety of Botulinum Toxin A (BTA) injections versus placebo injections, combined with pelvic floor muscle therapy (PFMT), in women with chronic pelvic pain (CPP). Randomised, double-blinded clinical trial (January 2020-April 2023). This multicentre study was conducted at four hospitals in the Netherlands. Ninety-four women with CPP and increased pelvic floor muscle tone despite previous PFMT, were enrolled. Participants received either BTA injections (100 units) or placebo injections into the pelvic floor muscle, followed by four PFMT sessions. Primary outcomes included the number of women with at least a 33% reduction in pain and those reporting (very) much improvement of their pain. Secondary outcomes covered quality of life and pelvic floor function. Follow-up visits were scheduled at 4, 8, 12, and 26 weeks post-treatment. Mixed models for repeated measurements were used for analysis. A 33% reduction or more in average pain score was reported by 15 participants (33%) after BTA treatment and 9 participants (20%) after placebo treatment (odd ratio placebo/BTA 1.88; 95% CI 0.72-4.90, p = 0.19). In both groups, 8 women (17%) reported their improvement as (very) much better (odd ratio placebo/BTA 0.947; 95% CI 0.32-2.80, p = 0.92). Pelvic floor resting activity decreased significantly after BTA treatment compared to placebo (p = 0.001). The results from this study do not support the use of BTA injections in the management of CPP in women.

Melasma Management: A Comprehensive Review of Treatment Strategies Including BTX-A.

Botulinum toxin A (BTX-A) is a widely utilized protein derived from the bacterium Clostridium botulinum, known for its effectiveness in treating various medical conditions involving muscle spasticity, involuntary muscle movements, and pain disorders. Beyond its therapeutic applications, BTX-A is also commonly used in cosmetic procedures to address dynamic wrinkles, hyperhidrosis, sebum production, pore size, and overall skin texture. While the use of neurotoxins like BTX-A for treating conditions such as UVB-induced hyperpigmentation, specifically melasma, is an emerging area of interest, it is not yet a widely recognized treatment for this dermatologic condition. This literature review serves to provide a consolidated overview of the current therapeutic implications of BTX-A treatment for melasma and explore its proposed mechanisms of action. This review aims to provide a comprehensive analysis of the current evidence base for the efficacy of BTX-A treatment on melasma. To gain a comprehensive understanding on the current theories regarding BTX-A treatment on melasma, a literature review was conducted on all the available information using PubMed. A combination of keywords was used to maximize the search results, including "botulinum toxin," "melasma," "melanogenesis," "neurotoxin," "cholinergic system," "BTX-A," and "UV-induced melasma." The search was not restricted by date, allowing for the inclusion of articles offering historical context and those providing the most recent findings. Ninety-eight articles were reviewed to provide a consolidated update on the effectiveness of botulinum toxin A in reducing the appearance of melasma and potential mechanisms of action involved in doing so. Melasma is a challenging dermatologic condition due to its chronicity and various intrinsic and extrinsic factors that influence its pathogenesis. While current treatment options for melasma include topical, oral, and light-based therapies, recent studies suggest that BTX-A may hold potential as a viable treatment modality for melasma. Despite the mechanism of action remaining unclear, it is hypothesized that BTX-A inhibition of Ach receptors on melanocytes could play a role in the reduction of melanogenesis. BTX-A treatment in melasma-affected skin demonstrates statistically significant reduction in hyperpigmented lesions associated with melasma.

Current Perspectives on the Adjunctive Use of Botulinum Toxin A in Endodontic Practice for Nonodontogenic Pain Management: A Web-Based Survey.

Despite the increasing use of botulinum toxin A (BoNT-A) in dentistry, there is limited research on its use in endodontics, a specialty that often receives referrals for dental pain that can coexist with nonodontogenic pain. The purpose of this study was to assess whether endodontists believe BoNT-A can be useful in an endodontic practice as an adjunctive treatment for nonodontogenic conditions overlapping with dental pain. A 23-question survey was emailed to 3,979 members of the American Association of Endodontists (AAE). Descriptive statistics, bivariate analysis, and logistic regression were performed with significance at α = 0.05. Among the 211 respondents confirmed to be endodontists in the United States, one in eleven (9.14%) currently administer BoNT-A treatment. The top nonodontogenic conditions indicated for BoNT-A were myofascial orofacial pain (49.22%) and temporomandibular joint disorders (41.97%). Half of the endodontists (50.26%) believe that BoNT-A could be useful for nonodontogenic conditions overlapping with dental pain. Regression analysis identified variables significantly associated with this belief: BoNT-A can improve patient satisfaction (p < 0.05), BoNT-A training should be offered in residency (p < 0.05), BoNT-A would increase profitability (p < 0.05), and BoNT-A will be incorporated more in the future (p < 0.05). Endodontists have split opinions on administering BoNT-A for nonodontogenic conditions overlapping with dental pain. Including BoNT-A training in residency may be key to encouraging multidisciplinary pain management in endodontics.

Staggered botulinum toxin-a injections into parotid and submandibular glands prior to four-duct ligation for pediatric sialorrhea.

This study aimed to assess the effectiveness of four-duct ligation following Botulinum toxin-A injections into the parotid and submandibular glands in pediatric patients with sialorrhea resistant to nonsurgical treatments. Prior research has individually explored either surgical or Botulinum toxin interventions; however, the safety and efficacy of the combined approach to these treatments have yet to be documented. Patients were assessed before surgery and 6, 12, and 24months post-operatively. Evaluations involved interviews with parents and caregivers, conducted face-to-face or by telephone, using the Drooling Severity and Frequency Scales. Additionally, metrics such as the daily count of bib changes and the hourly frequency of saliva wiping were recorded. Quality-of-life assessments were performed before and after the surgical procedures. All complications associated with the interventions were carefully recorded. The study group consisted of 25 participants, with a median age of 6years (range 2-17years). Each participant was diagnosed with a neurological, metabolic, or genetic disorder. Evaluations were conducted periodically, culminating in a final follow-up at 24months. The treatment demonstrated a 100% success rate at six months post-operation (25/25 patients), which slightly decreased to 96% at the 12-month mark (24/25 patients) and further to 84% by the 24-month follow-up (21/25 patients). Major complications were not observed. However, minor complications were reported in six patients (24%): three exhibited temporary facial swelling (12%), two encountered minor bleeding (8%), and one experienced excessive dryness (4%). The combination of Botulinum toxin-A injection 3 weeks prior to the four-duct ligation procedure demonstrated high success rates and substantially reduced the incidence of infectious and cosmetic complications. Consequently, this staggered approach to combination treatment is recommended for managing pediatric sialorrhea cases that are resistant to non-surgical interventions.

Resolving the Controversy Surrounding the Function of the Corrugator Supercilii Muscle.

The corrugator supercilii muscle (CSM) has traditionally been recognized as a primary depressor of the eyebrows, playing a key role in expressing negative emotions and contributing to the formation of glabellar lines. However, recent studies indicate that the CSM may exhibit movements contrary to those previously documented, suggesting a more complex functional role. This research re-evaluates the anatomical and functional roles of the CSM and discusses their implications for botulinum toxin treatments. A prospective, intrapersonal comparative, and split-face study was conducted over a five-year period, from January 6, 2019, to January 6, 2024, involving 298 patients who underwent botulinum toxin injections. The study divided participants into seven groups, each targeting specific anatomical areas of the CSM and associated muscles. Injection techniques were varied to assess their impact on brow dynamics, with outcomes measured by changes in eyebrow position and expression lines. The study demonstrated that targeting specific portions of the CSM and depressor supercilii muscle (DSM) leads to distinct outcomes in brow elevation and the reduction of expression lines. However, this approach was also frequently associated with the development of omega-shaped wrinkles. Split-face evaluations further validated that the modified injection techniques achieved superior eyebrow elevation compared to traditional methods. This study challenges the traditional view of the CSM as primarily a brow depressor, highlighting its role in medial brow elevation. These findings underscore the need for a nuanced approach in esthetic medicine, particularly in botulinum toxin injections, to achieve balanced and natural facial expressions. Understanding the full range of CSM functions is crucial for optimizing esthetic outcomes and enhancing patient satisfaction. 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 Treatment of Psoriasis-A Comprehensive Review.

A literature search on the subject of botulinum toxin treatment in psoriasis found 15 relevant articles, 11 on human subjects and 4 on animal studies. Of the human data, eight were clinical trials and three were single case reports. Seven out of eight clinical trials, all open-label, reported improvement in psoriasis following intradermal or subcutaneous botulinum toxin injections. One double-blind, placebo-controlled study, which used a smaller dose than the open-label studies, did not note a healing effect. Animal studies have shown that injection of botulinum toxins in the skin heals psoriatic skin lesions and can reduce the level of interleukins (ILs) and cytokines as well as inflammatory cells in psoriatic plaques. There is a need for controlled, blinded studies conducted in larger numbers of patients with doses that have shown promise in open-label studies.

Predisposing factors to pattern change in cervical dystonia.

Cervical dystonia (CD) patterns may change with Botulinum toxin (BoNT) treatment. To evaluate the time within those changes usually occur, the most predisposed phenotypes and predisposing factors. We divided idiopathic CD patients into two groups- change YES and NO, collecting general clinical and demographic variables. We also evaluated duration of BoNT treatment, Tsui total scores and subscores - assessed at T0 - before BoNT start - and at T1- time to chenge in the YES group or last visit in the NO group. The risk of pattern change was assessed by Kaplan Meyer curves and Cox regression analysis. Finally, Multivariate linear regressions were employed to assess if Tsui severity correlated with the change. Among 100 patients (60 women), 37 experienced a phenotype switch, mostly in the first five years of BoNT treatment, YES and NO groups were comparable. Multivariate Cox Regression revealed the presence of laterocollis or rotatocollis at T0 as predictors of switch (respectively P = 0.01, HR = 3.5; P = 0.03, HR = 1.5). Multivariate linear regressions revealed that high Tsui subscores for the tilt and low Tsui total scores were risk factors for the change of pattern (respectively P = 0.002, OR = 6; P = 0.03, OR = 0.8). Latero and Rotatocollis are the CD phenotypes most predisposed to change. CD characterized by neck tilt are more likely to change phenotype following treatment. Dystonias with a low degree of severity are more predisposed to switch. Both, the different degree of muscle activation and BoNT mechanism of action, may impact on that phenomenon.

Botulinum Toxin Treatment in a Patient with Facial Paralysis

Botulinum Toxin Treatment in a Patient with Facial Paralysis

Botulinum Toxin A for the management of temporomandibular myofascial pain - a cohort study

Myofascial pain represents the largest subgroup of TMD (Temporomandibular Disorders), which accounts for a common cause of non-dental orofacial pain. The management of TMD is complex, due to the chronic nature of the condition, alongside acute episodes presenting to the clinician. A fundamental part of TMD management is consideration of the bio-psycho-social element in the aetiology of TMD. First-line treatment of myofascial TMD includes; early diagnosis, explanation and education and conservative self-care measures. More recently, Botulinum Toxin A (BTX-A) is being used increasingly as an adjunct to conservative management of muskulo-skeletal pain disorders, due to its muscle-relaxant and analgesic properties. However, the scientific evidence regarding this is conflicting and it has been suggested that there is insufficient evidence to support the efficacy of BTX-A. A mixed method analysis of a TMD-myofascial pain cohort who underwent BTX-A injections to assess the effectiveness of masseteric BTX-A was carried out. 149 patients completed one round of masseteric BTX-A treatment, of whom 61 completed an additional round of BTX-A. In total, 398 masseter muscles were injected. The average VAS pain score pre-operatively was 8/10, compared with a postoperative mean score of 3/10 at 6 weeks after treatment. The mean percentage reduction in pain was 50%. Pain scores were classified as mild (≤4) , moderate (≤7) or severe (≥8). Pain scores and quality of life scores were found to improve considerably more in the severe pain group in comparison to the mild group. Complete resolution of symptoms was reported in 21% of patients (n=31). The treatment significantly improved patients’ reported pain and quality of life scores, highlighting key beneficial effects for the myofascial pain subgroup of TMD.

Pelvic floor muscle electrical coupling in chronic pelvic pain: Insights into pathophysiology and botulinum toxin treatment effects

This study aimed to assess the electrical coupling between both pelvic floor muscle (PFM) sides (two-sided coupling) and within individual PFM sides (one-sided coupling) in chronic pelvic pain (CPP) before and after botulinum neurotoxin type A (BoNT/A) treatment. Surface electromyographic (sEMG) signals were recorded from the left and right PFM of 24 patients (P) with CPP before and after being treated with BoNT/A (Weeks 0,8,12,24). Recordings were also made in 24 healthy women (H). PFM two-sided and one-sided coupling was evaluated during contractions by the cross-correlation (CC) and the imaginary part of coherency (iCOH) of their sEMG signals. Significant differences between their values were assessed comparing P(0) vs. P(8,12,24) and H vs. P(0,8,12,24). This study showed that PFM two-sided coupling is similar across groups before treatment, while PFM one-sided coupling on the patients’ most painful side is deranged before and also after BoNT/A treatment: amplitude coupling is lower (<CC) and phase difference is greater (>iCOH) than healthy women’s. This could be justified by altered neuromotor control strategies developed as an adaptation to muscle pain, structural and electrical changes in PFM, and alterations in their innervation pattern, which may influence the onset, perpetuation, or recurrence of CPP after treatment.

Mitigating adverse effects in botulinum toxin treatments: Best practices and key findings

Botulinum toxin, commonly known as Botox, is extensively used in both aesthetic and medical procedures due to its effectiveness in reducing wrinkles and treating conditions like cervical dystonia and hyperhidrosis. Despite its general safety, the use of botulinum toxin carries risks of adverse effects. Common immediate side effects include bruising, swelling, and pain at the injection site, which are usually mild and resolve within a few days. However, more serious complications, such as blepharoptosis (drooping eyelids), brow ptosis, and ocular sensory dysfunction, can occur and significantly impact facial expression and ocular function. Rare but severe adverse events include systemic spread of the toxin, leading to generalized muscle weakness and respiratory issues. These serious reactions require prompt medical attention and may be exacerbated by excessive doses or improper techniques. Long-term concerns include the formation of neutralizing antibodies, potentially reducing treatment effectiveness and altering facial dynamics over time. To minimize risks, it is crucial to select a qualified professional with experience in botulinum toxin administration, use precise injection techniques, and adhere to the smallest effective doses. Thorough patient evaluations and education about potential adverse effects and post-treatment care are essential. Regular monitoring and follow-ups help detect and address adverse effects promptly, with adjustments based on individual patient responses. Studies highlight the importance of these practices: Sethi et al. (2020) noted common adverse effects, Sorensen and Urman (2015) identified both common and rare complications, and Lee et al. (2020) linked serious outcomes to patient-specific factors. Coté et al. (2005) emphasized adherence to guidelines, while Witmanowski and Błochowiak (2019) discussed the distinction between benign and serious events. Laet and Wyndaele (2005) focused on rare generalized side effects in specific contexts.

The Goal Attainment Scale Refines Patient-Centered Expectations in Botulinum Toxin Treatment of Cervical Dystonia.

The Goal Attainment Scale Refines Patient-Centered Expectations in Botulinum Toxin Treatment of Cervical Dystonia.

Intragastric botulinum toxin injection directly regulates ghrelin expression via reactive oxygen species and NF-κB signaling

AimsOne effective clinical strategy to combat obesity is intragastric botulinum toxin (BTX) injection, which increases gastric emptying time and regulates appetite. However, it remains unknown if and how BTX affects ghrelin levels. Materials and methodsAn obese animal model was established by feeding male mice with high-fat diet (HFD). BTX was administered by subserosal injection in the antrum via an upper midline laparotomy. The mice were monitored in terms of body weight and blood biochemical parameters. Glucose utility and insulin sensitivity were measured by intraperitoneal glucose and insulin tolerance tests. Additionally, stomach and liver were histologically examined after BTX treatment. AGS gastric adenocarcinoma cells were used to investigate the molecular mechanism by which BTX affects ghrelin expression. Key findingsIn HFD-fed mice, BTX injection significantly decreased both food intake and body weight over a 3-week monitoring period. Moreover, HFD-induced hyperglycemia, hyperinsulinemia, dyslipidemia and obesity readouts were improved after BTX injection. Importantly, mice also exhibited decreased plasma and gastric ghrelin levels after BTX injection. In cultured AGS cells, BTX significantly increased reactive oxygen species (ROS) levels and activated nuclear factor-κB (NF-κB), which led to decreased ghrelin expression. Pre-treatment with inhibitors of either ROS or NF-κB reversed the effects of BTX on ghrelin expression in the cultured cells. SignificanceBTX decreases ghrelin expression in HFD-fed animals and in AGS cells through an ROS/NF-κB-dependent pathway. This mechanism may contribute to decreased food intake in obese subjects receiving intragastric BTX injection for weight control.

A Retrospective Study on Botulinum Toxin Injection in Patients With Multiple Sclerosis Related Tremor: A Treatment Option Worth Trying

Objectives Multiple sclerosis (MS)-related tremor remains a disabling problem that often responds poorly to medical treatments. This study aims to evaluate the effect of botulinum toxin type A on MS-related upper limb tremor. Methods This retrospective observational cohort study included 8 patients who received intramuscular injections of onabotulinum toxin type A for medically refractory MS-related tremor. Hospital records before and 4–6 weeks after treatment, including the Fahn-Tolosa-Marin Tremor rating scale (FTM-TRS), electrophysiological tremor analysis, neurological examination findings, and videos, were reviewed retrospectively. Results There was significant improvement after botulinum toxin injection in the FTM TRS part A score for tremor (P = 0.011), FTM TRS part B score for hand function (P = 0.011), FTM Part score for activities of daily living (P = 0.012), and FTM TRS total score for overall evaluation (P = 0.012). Electrophysiological tremor analysis revealed maximal tremor amplitudes between 700–2000 μV (before treatment) and between 300–1000 μV (after treatment). The mean tremor amplitudes before and after treatment were 1350 μV and 725 μV, respectively. No adverse reactions were observed after botulinum toxin treatment. Conclusions BoNT may improve upper limb tremor and functionality in MS-related tremor. The treatment involved administering BoNT under EMG guidance, with careful muscle selection based on clinical assessment and EMG findings. This approach aimed to optimize treatment efficacy while minimizing potential adverse effects. Further studies are warranted to confirm these findings.

Antipsychotics and chronic dystonia at a Botulinum Toxin clinic.

Chronic dystonia, characterised by sustained muscle contractions and abnormal postures, poses clinical challenges, especially when associated with antipsychotic medication use. To delineate the demographic and clinical profiles of adults with dystonia and examine the association with antipsychotic medication. Botulinum Toxin Clinic at Tygerberg Hospital, Cape Town, South Africa. We conducted a retrospective cohort study of adult patients seen at the Botulinum Toxin Clinic between January 2018 and June 2022. Of the 119 patients studied, those assessed with antipsychotic-induced dystonia (32.69%) presented at a younger age (p < 0.001), were more likely female (p = 0.04), received higher average dose of Botulinum toxin (p < 0.001), and incurred a higher estimated Botulinum toxin treatment cost (p = 0.01) compared to those with primary dystonia. Logistic regression identified age and Botulinum toxin dose as factors associated with psychotropic-related dystonia (p = 0.005 and p = 0.012, respectively). Clinical and demographic factors are associated with dystonia in adults taking antipsychotic medication. These patients generally manifested symptoms at an earlier age, had a higher male prevalence, and required prolonged treatment with Botulinum toxin, leading to increased costs. In those assessed with antipsychotic-induced dystonia, a comorbid diagnosis of a mood disorder was more common than that of a psychotic disorder. By identifying the demographic and clinical profile of individuals with dystonia because of antipsychotic medication, this study provides a basis for preventative strategies and enhanced patient care.

Do Botulinum Toxin Injections for Upper Face Rejuvenation and Lateral Canthal Rhytids Have Unintended Effects on Tear Production?

To report the influence of botulinum toxin A (BoNTA) injections on basal tear production, as measured by Schirmer's test with anesthesia in patients seeking eyelid surgery. A retrospective cohort of patients requesting esthetic eyelid surgery reviewed by a single clinician between January 2021 to April 2024, assessed with Schirmer's test with anesthesia. Demographic data, history of BoNTA treatment in the periocular region, ocular surface disease index dry eye symptom frequency, and requirement for ocular lubricants were recorded. Patients with no history of BoNTA were designated as group 1. Patients with a positive recent history of periocular BoNTA were designated as group 2. The proportions of eyes with Schirmer's test with anesthesia (basal tear production) test result <5 mm ("low"), 5 to 9 mm ("borderline"), and ≥10 mm ("normal") were compared between groups. Seven hundred twenty-two eyes (361 patients) were assessed, of which 670 eyes (335 patients) met the inclusion criteria. Mean age was 55.1 (range, 17-93) years, with 71.3% female. Schirmer's data in group 1 were "low" at 32.9%, "borderline" at 26.4%, and "normal" at 40.7%. In contrast, group 2 had significantly lower results (P ≤ 0.05), with readings "low" at 48.3%, "borderline" at 26.7%, and "normal" at 25.0%. However, there were no significant differences between groups in ocular surface disease index symptom frequency scores or ocular lubricant requirements. Patients who had received BoNTA injections had significantly lower basal tear production compared with patients who had never received BoNTA. Esthetic BoNTA treatment may be associated with an unintended effect of decreased basal tear production and subsequent risk of dry eye.

Predictive Factors for the Successful Outcome of Urethral Sphincter Injections of Botulinum Toxin A for Non-Neurogenic Dysfunctional Voiding in Women.

Dysfunctional voiding (DV) is not uncommon in women with non-neurogenic voiding dysfunction. Because of its unknown pathophysiology, effective and durable treatment is lacking. This study aimed to analyze the results of treatment and predictive factors for a successful outcome of botulinum toxin A (BoNT-A) treatment in female patients with DV. In total, 66 women with DV confirmed by a videourodynamic study (VUDS) were treated with a BoNT-A injection into the urethral sphincter once (n = 33) or several times (n = 33). VUDS was performed before (baseline) and after the BoNT-A treatment. Patients with a global response assessment of the voiding condition of 2 or 3 and a voiding efficiency (VE) of >20% than baseline were considered to have a successful outcome. The baseline demographics, VUDS parameters, and VUDS DV subtypes were compared between the successful and failed groups. Predictive factors for a successful outcome were investigated by logistic regression analyses. Successful and failed outcomes were achieved in 27 (40.9%) and 39 (59.1%) women, respectively. After BoNT-A injections, the maximum flow rate (Qmax), voided volume, and VE all significantly increased, and the postvoid residual (PVR) was slightly improved. No significant difference in the number of injections and medical comorbidity was found between the groups. However, the successful group had a higher incidence of previous pelvic surgery. No significant difference in the treatment outcome was found among patients with different urethral obstruction sites. Significant improvements in Qmax, voided volume, PVR, VE, and the bladder outlet obstruction (BOO) index were noted in the successful group. A lower VE at baseline and a history of surgery were identified as predictive factors for a successful outcome of BoNT-A injections for treating DV. BoNT-A injections into the urethral sphincter can effectively improve VE in 40.9% of women with DV. Women with higher BOO grades and previous pelvic surgery are predicted to have a successful treatment outcome.

Mitigating Immunogenicity by Coordinating Botulinum Toxin Treatments Between Aesthetics and Therapeutics.

Aesthetic use of botulinum toxin (BoNT) has expanded greatly beyond conventional low-dose (20 U) treatments, leading to some patients receiving doses previously reserved for therapeutic uses. The resulting risks are compounded in patients who receive BoNT for both aesthetic and therapeutic indications. Implementing tools for risk management is a high priority to prevent reduced treatment duration and effectiveness. To highlight the immunogenic risks of higher doses, with special attention to the compounding risks of resistance in patients with overlapping BoNT treatments from aesthetic and therapeutic indications. Authors examined the literature on current practices to provide a side-by-side comparison of BoNT doses for aesthetic and therapeutic indications. Aesthetic BoNT doses used in combination treatments of multiple areas or single treatments of large muscle areas can meet or exceed those observed in therapeutic treatments. Physicians have a responsibility to incorporate risk management and open dialog into their BoNT treatment plans to maximize effectiveness and longevity of treatments.

Does blepharospasm effect biometric parameters and intraocular lens power calculations?

To investigate the effect of botulinum toxin-A (BTX-A) treatment on corneal topography, ocular biometry and keratometry in patients with benign essential blepharospasm (BEB) and hemifacial spasm (HFS). This study comprised 66 eyes of 33 patients with BEB and 5 eyes of 5 patients with HFS who underwent BTX-A injections consecutively. Refractive error values, tear break-up time (TBUT), corneal topography [corneal power of flat axis (K1) and steep axis (K2), mean corneal power (Km), corneal astigmatism (K2-K1)] and ocular optical biometry [axial length (AL), anterior chamber depth (ACD)] were recorded before BTX-A treatment and 1 month after BTX-A treatment. The researchers calculated the expected emmetropic intraocular lens power (emm-IOL) using the SRK-T, Holladay, Hoffer-Q and Haigis formulas at each examination. K1 (43.48 ± 2.02 vs. 43.57 ± 2.08, p = 0.036), Km (43.91 ± 1.99 vs. 43.99 ± 2.06, p = 0.024) and ACD (3.22 (2.77-3.76) vs. 3.41 (2.99-4.02), p < 0.001) values were found to be significantly higher. The expected emm-IOL according to the SRK-T (21.04 ± 1.6 vs. 20.93 ± 1.6, p = 0.048), Holladay (21.05 ± 1.6 vs. 20.91 ± 1.62, p = 0.037) and Hoffer-Q (21.08 ± 1.65 vs. 20.94 ± 1.68, p = 0.038) decreased significantly. The expected emm-IOL according to the Haigis formula slightly decreased, but it was not significant (p = 0.386). Additionally, TBUT was found to be significantly lower (p < 0.001) after BTX-A injection. Other parameters were not statistically significant (p > 0.05). Our study is the first in the literature to compare optic biometry data and intraocular lens power calculation formulas before and after BTX-A injection in eyes with BEB and HFS. BTX-A injection could play an important role in changing the keratometric and ACD values. It should be considered that IOL power calculations that might be unpredictable due to blepharospasm, so repeated measurements and especially measurements after releasing the spasm with BTX-A injections, are necessary in BEB and HFS.

Assessing Changes in Hand Tactile Sensitivity After Glabellar Botulinum Toxin Treatment.

We aimed to assess behavioral changes in tactile sensitivity in patients receiving cosmetic glabellar botulinum toxin-A injections. In this prospective cohort study, we conducted quantitative sensory testing on 20 patients receiving 15 to 35 units of glabellar botulinum toxin-A treatment between October 1, 2022 and March 8, 2023. We used modified Von Frey filaments to exert forces between 0.25 mN and 512 mN to the dorsal hand just prior to botulinum toxin-A injections. Filament tips were uniform, rounded, and 0.5 mm in diameter to prevent nociceptor activation. This process was repeated 4 to 6 weeks after injection to assess for any change in minimal mechanical detection thresholds. Minimal mechanical detection thresholds decreased (patients detected smaller amounts of force) overall, in patients with prior botulinum toxin-A treatment, and in patients without prior botulinum toxin-A treatment: 5.34 mN to 4.33 mN (p = 0.22), 6.43 mN to 5.97 mN (p = 0.31), and 4.44 mN to 3.00 mN (p = 0.53), respectively. Our results suggest that the plastic changes observed in previous studies do not necessarily result in clinically significant manifestations when utilizing small to moderate amounts of botulinum toxin-A for aesthetic correction of glabellar lines, thus highlighting the safety of botulinum toxin-A for this indication. Further research is required to gain a comprehensive understanding of whether hand-associated cortical activity is altered after aesthetic amounts of botulinum toxin are injected.