Contemporary Review and Case Report of Botulinum Resistance in Facial Synkinesis

Toxin for Treating Raynaud Conditions in Hands (The TORCH Study): A Systematic Review and Meta-analysis

Background

Raynaud disease of the hands is a complex disorder resulting in inappropriate constriction and/or insufficient dilation in microcirculation. There is an emerging role for botulinum toxin type A (BTX-A) in the treatment armamentarium for refractory Raynaud disease. The aim of this systematic review was to critically evaluate the management of primary and secondary Raynaud disease treated with BTX-A intervention.

Methods

We performed a Preferred Reporting Items for Systematic Reviews and Meta-Analyses-compliant systematic review of clinical studies assessing treatment of primary or secondary Raynaud disease with BTX-A by searching Ovid MEDLINE and Embase databases from inception to first August 2023. The review protocol was prospectively registered on the PROSPERO database (CRD42022312253).

Results

Our search strategy identified 288 research articles, of which 18 studies [four randomized controlled trials (RCTs), two non-RCTs, five case series, and seven retrospective cohort studies] were eligible for analysis. Meta-analysis demonstrated that the probability of pain visual analog scale score improvement with BTX-A intervention was 81.95% [95% confidence interval (74.12-87.81) P = 0.19, heterogeneity I 2 = 26%] and probability of digital ulcer healing was 79.37% [95% confidence interval (62.45-89.9) P = 0.02, heterogeneity I 2 = 56%].

Conclusions

Delivery of BTX-A to digital vessels in the hand may be an effective management strategy for primary and secondary Raynaud disease. A definitive, appropriately-powered RCT with objective functional and patient-reported outcome measures is required to accurately assess and quantify the efficacy of BTX-A in Raynaud disease of the hands.

Objective Assessment of the Repeated Botox Treatment to the Synkinesis of Facial Paralysis by the Integrated Electromyography

BACKGROUND

The widely used botox type A (BTX-A) is effective against synkinesis in facial palsy sequelae. Repeated injections are necessary and permanent improvements have been reported. We objectively evaluated the changes in synkinesis at >6 months after BTX-A injection, including changes over time with the number of administrations.

METHODS

In 48 patients who received multiple BTX-A injections, evaluation by the Sunnybrook Facial Grading System (FGS) and integrated electromyography (iEMG) was performed before treatment and at least 6 months after the first, second, and third BTX-A injection. The iEMG ratio on the affected and healthy sides was calculated for each mimetic muscle and mimic motion.

RESULTS

There was no significant difference in the FGS synkinesis score before treatment and after the third injection, although an improvement was observed. The iEMG ratio was significantly improved in the orbicularis oculi with open-mouth smile and lip pucker after the third dose compared to before treatment. The orbicularis oris showed a significant improvement when the eyelids were closed, while the platysma showed a significant improvement when the eyelids were closed and when the lip was pursed. Multiple regression analysis revealed that the orbicularis oculi and platysma had a greater effect on the iEMG ratio for the number of treatments than other factors.

CONCLUSIONS

Repeated BTX-A injections showed improvements in synkinesis for the orbicularis oculi, orbicularis oris, and platysma, even after >6 months, compared to before treatment.

Botulinum toxin A treatment in facial palsy synkinesis: a systematic review and meta-analysis

BACKGROUND

Synkinesis is defined as involuntary movements accompanying by voluntary movements and can occur during the aftermath of peripheral facial palsy, causing functional, aesthetic and psychological problems in the patient. Botulinum toxin A (BTX-A) is frequently used as a safe and effective treatment; however, there is no standardized guideline for the use of BTX-A in synkinesis. The purpose of this article is to review and summarize studies about the BTX-A treatment of synkinesis in patients with a history of peripheral facial palsy; including given dosages, injection sites and time intervals between injections.

MATERIALS AND METHODS

A multi-database systematic literature search was performed in October 2020 using the following databases: Pubmed, Embase, Medline, and The Cochrane Library. Two authors rated the methodological quality of the included studies independently using the 'Newcastle-Ottawa Quality Assessment Scale' for non-randomised studies' (NOS).

RESULTS

Four-thousand-five-hundred-and-nineteen articles were found of which 34 studies met the inclusion criteria, in total comprising 1314 patients. Most studies were assessed to be of 'fair' to 'good' methodological quality. The Cohen's kappa (between author FJ and AS) was 0.78. Thirty-one studies investigated the reported dosage injected, 17 studies reported injection location and 17 studies investigated time intervals. A meta-analysis was performed for three studies comprising 106 patients, on the effects of BTX-A treatment on the Synkinesis Assessment Questionnaire (SAQ) scores. The mean difference was 11.599 (range 9.422-13.766), p < 0.01. However, due to inconsistent reporting of data of the included studies, no relationship with the dosage and location could be assessed.

CONCLUSIONS

Many treatment strategies for synkinesis exist, consisting of varying BTX-A brands, dosages, time intervals and different injection locations. Moreover, the individual complaints are very specific, which complicates creating a standardized chemodenervation treatment protocol. The BTX-A treatment of long-term synkinesis is very individual and further studies should focus on a patient-tailored treatment instead of trying to standardize treatment.

Immunogenicity of Botulinum Toxin Formulations: Potential Therapeutic Implications

Botulinum neurotoxins (BoNTs) are proteins produced by bacteria of the Clostridium family. Upon oral ingestion, BoNT causes the neuroparalytic syndrome botulism. There are seven serotypes of BoNT (serotypes A-G); BoNT-A and BoNT-B are the botulinum toxin serotypes utilized for therapeutic applications. Treatment with BoNT injections is used to manage chronic medical conditions across multiple indications. As with other biologic drugs, immunogenicity after long-term treatment with BoNT formulations may occur, and repeated use can elicit antibody formation leading to clinical nonresponsiveness. Thus, approaching BoNT treatment of chronic conditions with therapeutic formulations that minimize stimulating the host immune response while balancing patient responsiveness to therapy is ideal. Immunogenicity is a clinical limitation in many settings that use biologic drugs for treatment, and clinically relevant immunogenicity reduction has been achieved through engineering smaller protein constructs and reducing unnecessary formulation components. A similar approach has influenced the evolution of BoNT formulations. Three BoNT-A products and one BoNT-B product have been approved by the Food and Drug Administration (FDA) for therapeutic use: onabotulinumtoxinA, abobotulinumtoxinA, incobotulinumtoxinA, and rimabotulinumtoxinB; a fourth BoNT-A product, daxibotulinumtoxinA, is currently under regulatory review. Additionally, prabotulinumtoxinA is a BoNT-A product that has been approved for aesthetic indications but not therapeutic use. Here, we discuss the preclinical and clinical immunogenicity data that exist within the scientific literature and provide a perspective for considering immunogenicity as a key factor in choice of BoNT formulation.