DaxibotulinumtoxinA Treatment for Laryngeal Respiratory Dystonia.

Abstract

Background: Laryngeal respiratory dystonia (LRD) is diagnosed based on clinical presentation, patient history, and physical examination. Key indicators include dyspnea, desynchronized breathing patterns, and laryngoscopic findings that reveal vocal fold adduction during inspiration. Treatment for LRD remains controversial and often yields limited effectiveness. While botulinum toxin type A (BtxA) is commonly injected into the thyroarytenoid-lateral cricothyroid (TA-LCA) muscle complex, there are cases where injections into the interarytenoid (IA) muscle have also proven beneficial. DaxibotulinumtoxinA (DAXI) is an emerging therapy that has shown promising effectiveness and safety across various conditions, including cervical dystonia. In this report, we present the first documented use of DAXI specifically for LRD, highlighting the significant benefits experienced by the patient compared to previous treatments with BtxA.

Case: A 77-year-old man presented with a 1-year history of significant shortness of breath. Laryngeal endoscopy demonstrated inappropriate adduction of the patient's vocal folds during respiration, suggestive of LRD. The patient received their first Botox (BtxA) injection in May 2018 and has since undergone a total of 40 injections. The patient had a variable response to BtxA injection into his TA-LCA muscle complex, experiencing general improvement in breathing but frequent negative impact on voice and swallowing function. In November of 2021, electromyography-guided BtxA injection into the patient's IA muscle was performed with significant improvement in results. The patient described near-complete resolution of his LRD breathing symptoms with minimal voice changes and a duration of benefit of ~50 days. In November of 2023, DAXI injection into the patient's IA muscle was performed. The patient self-reported a complete resolution of his symptoms for a total duration of benefit of 91 days. Subsequent injections with DAXI in February and May of 2024 had near identical responses.

Conclusion: DAXI appears to provide ~80% better duration than the patient's average BtxA injection and a 57% improvement than his best BtxA injection. DAXI is a safe and realistic alternative to BtxA injection in patients with LRD.