Impact of an Upper Respiratory Tract Infection on Botulinum Toxin Efficacy in Spasmodic Dysphonia Patients.

<bold>Objective: </bold>To determine whether the presence of a concomitant upper respiratory tract infection (URI) impacts upon Botulinum toxin (BoNT) efficacy in spasmodic dysphonia (SD) patients.<bold>Study Design: </bold>Case series and literature review.<bold>Methods: </bold>All SD patients with a concurrent URI, presenting for BoNT therapy at a clinical research center from November 2016 to December 2017 were included. A total of 12 patients were identified. Patients were followed for at least two BoNT treatment cycles (approximately 6 months). The primary outcome measure was efficacy of the initial BoNT injection and the secondary outcome measure was the efficacy of the subsequent BoNT injection.<bold>Results: </bold>All subjects had adductor type SD (ADSD). There were 10 females and two males with a median age of 55 years (±19.5). All patients were well established on a consistent BoNT treatment regime, with an average administered dose of 1.0 unit (range 0.2-1.80 units). Bilateral injections were administered to 10 patients. Regarding the primary outcome measure, five failed to have any response to BoNT (41.7%), four had a partial response (33.3%), and three had a positive response to treatment (25.0%). When patients had their follow-up injection in the absence of URI symptoms, 11 patients had a positive response to treatment (91.7%).<bold>Conclusion: </bold>While the interplay between illness and BoNT efficacy is yet to be elucidated, we report that some patients are affected. We recommend that SD patients presenting for BoNT administration with a concomitant URI, should be counseled that their treatment might have decreased effect.<bold>Level Of Evidence: </bold>4 Laryngoscope, 130:1746-1749, 2020. [ABSTRACT FROM AUTHOR]