In the last decade, there has been a significant increase in the number of practitioners administering botulinum toxin for facial synkinesis. However, there are few resources available to guide treatment patterns, and little is known about how these patterns are associated with functional outcomes and quality of life.OBJECTIVE To evaluate botulinum treatment patterns, including the dosing and frequency of muscle targeting, for treatment of facial synkinesis and to quantify patient outcomes. DESIGN, SETTING, AND PARTICIPANTSThis prospective cohort study of 99 patients treated for facial synkinesis was conducted from January 2016 through December 2018 at the Vanderbilt Bill Wilkerson Center in Nashville, Tennessee, a tertiary referral center.INTERVENTION Onabotulinum toxin A treatment of facial synkinesis. MAIN OUTCOMES AND MEASURES Patient-reported outcomes on the Synkinesis AssessmentQuestionnaire and botulinum treatment patterns, including the dosages and frequency of injection for each facial muscle, were compared at the initiation of treatment and at the end of recorded treatment. RESULTSIn total, 99 patients (80 female patients [81%]) underwent botulinum injections for treatment of facial synkinesis. The median (interquartile range) age was 54.0 (43.5-61.5) years, and the median (interquartile range) follow-up was 27.1 (8.9-59.7) months. Most patients underwent injections after receiving a diagnosis of Bell palsy (41 patients, 41%) or after resection of vestibular schwannoma (36 patients [36%]). The patients received a total of 441 treatment injections, and 369 pretreatment and posttreatment Synkinesis Assessment Questionnaire scores were analyzed. The mean botulinum dose was 2 to 3 U for each facial muscle and 9 to 10 U for the platysma muscle. The dose increased over time for the majority of all muscles, with steady state achieved after a median of 3 treatments (interquartile range, 2-3). Linear regression analysis for cluster data of the mean total questionnaire score difference was −14.2 (95% CI, −17.0 to −11.5; P < .001). There was a significant association of postinjection questionnaire score with younger patients, female sex, total dose, and synkinesis severity. Oculo-oral synkinesis may respond more to treatment compared with oro-ocular synkinesis.CONCLUSION AND RELEVANCE Patients with facial synkinesis responded significantly to botulinum treatment. Treatment began with 6 core facial muscles that were injected during most treatment sessions, and dosages increased after the first injection until steady state was achieved. Those with a greater degree of morbidity, younger patients, and females showed significant improvement, and the larger the dose administered, the greater the response. Oculo-oral synkinesis may be more responsive than oro-ocular synkinesis.LEVEL OF EVIDENCE 3.

Background Botulinum resistance poses significant treatment challenges for both patients and healthcare practitioners. We first present a case highlighting botulinum resistance in a patient who failed to respond to alternative formulations but who responded remarkably to incobotulinum toxinA, an identical toxin free of complexing proteins. Secondly, we provide a treatment algorithm and a review of the literature detailing clinical and immunochemical botulinum resistance. Results Patients with botulinum resistance show a predisposition to failure on subsequent injections and possess a propensity toward neutralizing and nonneutralizing antibody development. The mechanisms of resistance are not entirely understood but thought to be secondary to an immunologic response. Risk factors for resistance include higher botulinum doses, more frequent injections, and high total lifetime dosage. Patients may still respond to other botulinum formulations or subtypes; however, this effect may be temporary. Conclusion This case report describes a patient who responded to incobotulinum toxinA after failing treatment with the identical toxin compounded with buffer proteins, ultimately supporting the possibility of immune‐mediated resistance to the surrounding proteins and not the toxin itself. Often, impending treatment resistance is preceded by a poor or limited clinical response. Antibody testing is not indicated because it is neither sensitive nor specific and does not change clinical practice. Initially, higher doses of botulinum may overcome resistance without increasing treatment frequency, and side effects are far less common in those with clinical resistance. If higher dosages fail to produce a response, alternative botulinum formulations or subtypes can be considered. Laryngoscope, 129:2269–2273, 2019

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