Complications of botulinum toxin a and their adverse effects

Factors Affecting the Efficacy of Botulinum Toxin Injection in the Treatment of Infantile and Partially Accommodative Esotropia

PURPOSE

We aimed to investigate the effect of botulinum toxin (BT) injection on the treatment of infantile and partially accommodative esotropia (PAET).

METHODS

This retrospective cohort study included patients who received BT injections for infantile and PAET between January 2015 and December 2018. Treatment was considered successful if orthotropia, consecutive exotropia, or esotropia within 10 prism diopters (PD) was achieved.

RESULTS

The overall success rate was 47.4%, with a mean follow-up period of 27.8 months in 403 children. BT treatment was considered successful in 37.1% of cases of infantile esotropia and 53.1% of cases of partially accommodative esotropia. The average deviation angle before starting treatment was 35.5 ± 13.9 PD. Side effects 1 week after BT injections included transient overcorrection (63.8%) and transient ptosis (41.7%). There were no significant differences in the success rates between the different doses of BT (P = 0.69). The angle of deviation at presentation was significantly associated with the success rate of BT injection (failed group, mean: 38.1 ± 15.3 PD vs. success group, mean: 32.6 ± 11.6 PD; P < 0.001). Other factors associated with higher success rates were overcorrection at 1 week and PAET, while multivariate logistic regression analysis showed that a smaller angle of deviation and overcorrection (1 week after injection) were associated with a higher success rate.

CONCLUSION

A smaller angle of deviation and transient overcorrection were associated with a higher success rate, and no significant difference was observed in the success rates of different BT doses.

Essential Infantile Esotropia: A Course of Treatment From Our Experience

Background: Essential infantile esotropia (EIE) is the most common type of childhood esotropia. Although its classical approach is surgical, less invasive techniques have been proposed as an adjunct or alternative to traditional surgery. Among them, chemodenervation with botulinum toxin (BT) has been investigated, showing variable and sometimes conflicting results. Objectives: To compare the outcomes of bilateral BT injection and traditional surgery in a pediatric population with EIE in order to optimize and standardize the therapeutic approach. Other purposes are to evaluate whether early intervention may prevent the onset of vertical ocular deviation (which is part of the clinical picture of EIE) and/or influence the development of fine stereopsis, and also to assess changes in refractive status over time among the enrolled population. Methods: A retrospective consecutive cohort study was conducted in 86 children aged 0-48 months who underwent correction of EIE. The primary intervention in naïve subjects was either bilateral BT injection (36 subjects, "BT group") or strabismus surgery (50 subjects, "surgery group"). Results: Overall, BT chemodenervation (one or two injections) was effective in 13 (36.1%) subjects. With regard to residual deviation angle, the outcomes at least 5 years after the last intervention were overlapping in children receiving initial treatment with either injection or surgery; however, the success rate of primary intervention in the surgery group was higher, and the average number of interventions necessary to achieve orthotropia was smaller. Both early treatment with chemodenervation and surgery at a later age were not found to prevent the onset of vertical ocular deviation, whereas, surprisingly, the percentage of subjects developing fine stereopsis was higher in the surgery group. Finally, with regard to the change in refractive status over time, most of the subjects increased their initial hyperopia, whereas 10% became myopic. Conclusions: Our data suggest that a single bilateral BT injection by age 2 years should be considered as the first-line treatment of EIE without vertical component; whereas, traditional surgery should be considered as the first-line treatment for all other cases and in subjects unresponsive to primary single BT injection.

The Use of Botulinum Toxin in Strabismus Treatment

There is a long and extensive experience with the use of Botulinum Toxin type A (BoNT-A) injection in the treatment of different types of strabismus and oculomotor palsies. The frequency of its use varies depending on the country and institution. It is a short procedure, may reduce general anesthesia exposure, causes minimal scarring compared to surgery, and can be proposed as an early treatment in unstable strabismus. Over many years, the experience of using BoNT-A indications has been refined and new applications have been reported. The use of BoNT-A in the postoperative period, after strabismus surgery or during surgery, can also be beneficial.

The whole truth about botulinum toxin - a review

Treatment with botulinum toxin is widely viewed as safe, effective and largely devoid of serious side effects. There are two classes of Botox-related adverse events – transient and benign events, and potentially serious events. The aim of this study was to provide an overview of Botox-related side effects and advise potential management and preventive strategies. Benign side effects are well-localized, reversible and self-limited complications which develop within a few days of the injection, and they usually disappear without any treatment. The aesthetic and functional adverse effects are associated with different muscle responses to botulinum toxin or with misplacement of botulinum toxin. The serious events are sequelae due to the systemic spread of toxin leading to botulism.

Botulinum toxin injection in the patients with Duane syndrome type 1

PURPOSE

To evaluate the efficacy of botulinum toxin injection in the patients with type 1 Duane syndrome and identify the predictive factors for success.

METHODS

Sixteen patients with esotropic type 1 Duane syndrome without history of ocular surgery were selected for this interventional case series. The botulinum toxin was injected in the medial rectus of all patients. Visual acuity, dry refraction, cyclo-refraction, ocular motility, and amount of deviation were measured. Complete success, partial success, and failure were defined as residual deviation/face turn less than 8 prism diopters (PD)/5°, 8-20 PD/5-15°, and equal or greater than 20 PD/15°, respectively.

RESULTS

Sixteen cases (6 males) were included in our study. The mean esotropia was 26.27 ± 8.35 (12-40 PD) which was reduced significantly to 13.5 ± 12.39 PD during 6 months follow-up (p < 0.001). Face turn was improved significantly from a preoperative mean of 18.27° to: 0.094° at 1 week, 0.11° at 1 month, 3.31° at 3 months, and 7° at 6 months (p < 0.001). Complete success was seen in 6 patients (37.5%), partial success in 4 patients (25%), and failure in 6 patients (37.5%). There was a significant relation between the amount of forced duction testing (FDT) and the success rate (p: 0.019). No complication was seen during injections.

CONCLUSIONS

Botulinum toxin could be an alternative treatment in Duane syndrome with appropriate case selection. FDT could be a predictive factor for response to botulinum toxin.

Botulinum toxin type A as treatment of partially accommodative esotropia

OBJECTIVE

To determine the effectiveness of a botulinum toxin type A injection in both medial rectus muscles in patients with partially accommodative esotropia. Residual deviation and stability of strabismus were evaluated at 18 months follow up.

METHOD

A prospective, analytical, quasi-experimental study was conducted on a cohort of 21 patients who underwent total cycloplegic refraction and with a residual deviation of at least 14 DP. A botulinum toxin type A dose of 5 IU was injected into each medial rectus muscle for a residual deviation greater than 18 DP, with a dose of 2.5 IU being used for a deviation between 14 and 18 DP. Multivariate logistic regression analyses were performed to relate residual deviation to variables recorded as potential predictors.

RESULTS

A total of 21 patients were included, 33.3% (n=7) males and 66.6% (n=14) females. Mean visual acuity was -.28±.25 logMAR for right eye (range 0 to -1) and -.42±.31 logMAR for left eye (range 0 to -1.3). Mean angle of residual deviation before application of botulinum toxin was 40.95±8.6DP without spectacles correction, and 22.3±7.99 DP with full cycloplegic refraction. Adverse effects were ptosis in 14.2% (n=3), diplopia 23.8% (n=5), and vertical deviation in 33% (n=7). One patient had a poor outcome, therefore required surgical treatment. At one year follow up, 85.71% of patients showed good results with esotropia of 12 DP or less, dropping to 71.43% at 18 months of follow up.

CONCLUSION

Botulinum toxin type A is an effective long-term treatment with a good response in 71.43% of patients. No predictors of good response were demonstrated.

An external pilot study to test the feasibility of a randomised controlled trial comparing eye muscle surgery against active monitoring for childhood intermittent exotropia [X(T)]

INTRODUCTION

The evidence base for the treatment of strabismus (squint) is poor. Our main aim is to improve this evidence base for the treatment of a common type of childhood squint {intermittent exotropia, [X(T)]}. We conducted an external pilot study in order to inform the design and conduct of a future full randomised controlled trial (RCT).

METHODS

Children of between 6 months and 16 years with a recent diagnosis of X(T) were eligible for recruitment. Participants were recruited from secondary care at the ophthalmology departments at four UK NHS foundation trusts. Participants were randomised to either active monitoring or surgery. This report describes the findings of the Pilot Rehearsal Trial and Qualitative Study, and assesses the success against the objectives proposed.

RECRUITMENT AND RETENTION

The experience gained during the Pilot Rehearsal Trial demonstrates the ability to recruit and retain sites that are willing to randomise children to both trial arms, and for parents to agree to randomisation of their children to such a study. One child declined the group allocation. A total of 231 children were screened (expected 240), of whom 138 (60%) were eligible (expected 228: 95%) and 49 (35% of eligible) children were recruited (expected 144: 63% of eligible). Strategies that improved recruitment over the course of the trial are discussed, together with the reasons why fewer children were eligible for recruitment than initially anticipated. Attrition was low. Outcome data were obtained for 47 of 49 randomised children.

TRIAL PROCESSES AND DATA COLLECTION

The Trial Management processes proved effective. There were high levels of completion on all of the data collection forms. However, the feedback from the treatment orthoptists revealed that some modifications should be made to the length and frequency of the health service assessment and travel assessment questionnaires, thus reducing the burden on participants in the main trial. Modifications to the wording of the questions also need to be made.

MONITORING OF BIAS

Children who recruited to the trial were older and had more severe strabismus than those children eligible but declining participation. Strategies to account for this in a full trial are proposed.

REASONS FOR PARTICIPATION OR DECLINING STUDY

These were identified using qualitative interviews. The principal reasons for declining entry into the study were strong preferences for and against surgical treatment.

HARMS

There were no serious unexpected adverse events. Two children had overcorrection of their X(T) with reduction in binocular vision following surgery, which is in line with previous studies. No children in the active monitoring arm developed a constant strabismus although two showed some reduction in control.

CONCLUSIONS

The SamExo study has demonstrated that it is possible to recruit and retain participants to a randomised trial of surgery compared with active monitoring for X(T). For longer-term full RCTs, in order to maximise the generalisability of future studies, consideration needs to be given to planning more time and clinic appointments to assess eligibility and to allow consideration of participation; the greater use of research nurses for recruitment; and accommodating the strong preferences of some parents both for and against surgical intervention.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN44114892.

FUNDING

This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 19, No. 39. See the NIHR Journals Library website for further project information.

Ocular surface changes following botulinum toxin injection for strabismus

CONTEXT

Botulinum toxin injection is widely used for many purposes, including neuromuscular diseases, movement disorders and strabismus.

OBJECTIVE

To evaluate and report the impact of botulinum toxin injection on ocular surface parameters in patients with strabismus.

PARTICIPANTS

Twenty-six consecutive patients who underwent botulinum toxin A injection for ocular misalignment were recruited for this prospective study.

MATERIALS AND METHODS

Testing of ocular surface parameters including tear break-up time (BUT), lissamine green (LG) staining and Schirmer test (under topical anesthesia) was performed, and Ocular Surface Disease Index (OSDI) questionnaire scores were recorded before and at certain time points after injection (one week, two weeks, one month, three months and six months after botulinum toxin A injection). Two-way analysis of variance (ANOVA) with repeated measures, Friedman's test and Wilcoxon test were used for statistical analysis.

RESULTS

Twenty six patients (15 eso- and 11 exo-deviations) with a mean age of 32.46 ± 14.41 (17-65) years were recruited for the study. All injections were performed in one eye. The mean amount of deviation at near and distance reduced after injection. The change of BUT, LG staining and OSDI scores was found to be significant during follow-up in treated eyes (p = 0.001, p = 0.007 and p = 0.009, respectively) whereas the change was insignificant for the Schirmer test results (p = 0.266).

CONCLUSIONS

The ocular surface parameters appear to be altered by botulinum toxin injection in strabismic patients. Even though these effects seemed to be temporary, the findings of the present study support the notion of botulinum toxin effects on ocular surface parameters.

Botulinum Toxin as an Alternative to Treat the Spasm of the Near Reflex

We describe the case of an eight-year-old girl with complaints of headaches and blurred vision (uncorrected visual acuity: 0.1 decimal) that showed on examination miotic pupils, pseudomyopia, no ocular motility restrictions, and no associated neurological disease. After initial treatment with cyclopentolate for two months, pseudomyopia persisted with an intermittent and variable esotropia. Spectacles of +1 both eyes and atropine 1% one drop daily were then prescribed. The situation improved and remained stable for several weeks, with pseudomyopia and esotropia reappearing later. Finally, botulinum toxin (2.5 iu Botox) was injected in the medial rectus muscle on two occasions and a visual therapy program based on the stimulation of fusional divergence, diplopia, and stereopsis consciousness was recommended. This prescription was combined with the use of atropine during the first few weeks. Orthotropia and corrected distance visual acuity of 1.0 were found three months after treatment. The evolution and clinical results of this case report suggest that botulinum toxin in combination with other therapeutic alternatives may be useful in the treatment of spasm of the near reflex.

Uses of Botulinum Toxin a in Ophthalmology

Introduction:

Botox® (serotype A) is currently available and used to treat various ophthalmological conditions. The aim of our study was to review the current indications, side-effects and updates on the clinical use of botulinum toxin- A (Btx-A) in the field of ophthalmology.

Methods:

A literature search using the keywords “Botulinum Toxin”, “Botulinum Toxin A”, “Botox” and “Ophthalmology” was performed using Pubmed. Articles describing the use of botulinum toxin A were selected and reviewed.

Results:

The uses of Btx-A in ophthalmology can be broadly classified into four categories: eyelid, strabismus, cosmetic and others. In the eyelid, it can be used to treat blepharospasm, hemifacial spasm, apraxia of lid opening or induce ptosis in lid retraction and exposure keratopathy. In strabismus management, it can be injected into overacting muscles to realign the eyes. For cosmesis, it can be used to relax facial muscles to reduce wrinkles while other indications include treatment of chronic dry eye, lacrimal hypersecretion and pain relief in acute angle closure attack. Complications of the injection include local effects like ecchymosis, pain or infection and spillover effects like ptosis, diplopia, lagophthalmos, mid facial weakness and dry eyes.

Conclusion:

The clinical application of botulinum toxin A in ophthalmology is extensive. When considering its application in clinical practice, one should be mindful of the indications, risks and benefits of the procedure. When properly delivered, its potential as an efficacious, minimally-invasive treatment modality can be maximised in patient management.

Botulinum toxin type a inhibits connective tissue growth factor expression in fibroblasts derived from hypertrophic scar

BACKGROUND

Botulinum toxin type A (BTXA) can inhibit the growth of hypertrophic scars, but the molecular mechanism for this action is unknown. In addition to reducing the tension around the wound by stimulating temporary denervation, a growing body of evidence suggests that BTXA is involved in regulating the cell cycle and decreasing transforming growth factor-β1 (TGF-β1) expression in the fibroblasts of hypertrophic scars. Connective tissue growth factor (CTGF) is a downstream regulator of TGF-β1 function and an independent mediator of scarring and fibrosis. The effects of BTXA on CTGF in hypertrophic scar still are unknown. This study aimed to explore the effect of BTXA on CTGF in fibroblasts derived from hypertrophic scar and to elucidate its actual mechanism further.

METHODS

Fibroblasts isolated from tissue specimens of hypertrophic scar were treated with BTXA. The difference in proliferation between treated and nontreated fibroblasts was analyzed by flow cytometry. Proteins of CTGF were checked using Western blot in fibroblasts with and without BTXA.

RESULTS

The proliferation of the fibroblasts treated with BTXA was slower than that of the fibroblasts that had no BTXA treatment (p < 0.01), which showed that BTXA effectively inhibited the growth of fibroblasts. Compared with fibroblasts that received no BTXA treatment, BTXA at 1 U/10(6) cells decreased the expression of CTGF by 49.2% ± 12.5% (p < 0.01), and BTXA at 2.5 U/10(6) cells decreased the expression of CTGF by 56.9% (p < 0.01).

CONCLUSION

These results suggest that BTXA effectively inhibited the growth of fibroblasts derived from hypertrophic scar and in turn caused a decrease in CTGF protein, providing theoretical support for the application of BTXA to control hypertrophic scarring.