[Botulinum toxin type A-induced "rebalancing" in bilateral vocal cord paralysis?]

Upper airway obstruction due to bilateral vocal cord paralysis in an 80-year-old female patient was successfully relieved by injection of botulinum toxin A (BTA) into the laryngeal adductor muscles. The patient achieved satisfactory airway ventilation. Spirograms obtained preoperatively and postoperatively documented improved peak flow rates and 1-s forced expiratory volume values. Voice quality was breathy after the injection; however, neither aspiration nor dysphagia developed. Surprisingly, the maximum phonation time increased.

During a follow-up check 4 months later, the patient still reported less dyspnea although the vocal cords were closer together than initially after the injection. The decrease in dyspnea as reported by the patient lasted approximately 2 years.

The improvement in breathing following injection of BTA can be interpreted as a paralysis or weakening of the laryngeal adductors. However, it remains unclear why the maximum phonation time increased. Comparable findings, i.e., improvement in overall laryngeal function, are described in the literature as BTA-mediated laryngeal rebalancing.