IncobotulinimtoxinA (Xeomin) for the treatment of adductor laryngeal dystonia: A prospective, open-label clinical trial.

[OBJECTIVES] Demonstrate an understanding of incobotulinumtoxinA efficacy in the treatment of adductor spasmodic dysphonia (SD). Understand that incobotulinumtoxinA can successfully be used as an alternative to onabotulinumtoxinA and for secondary non-responders.

[METHODS] We conducted a prospective open-label trial from 2016 until 2019 regarding the use of incobotulinimtoxinA for the treatment of adductor spasmodic dysphonia. Exclusion criteria included pregnant/nursing women, botulinum toxin for other indications, known allergy, neuromuscular or systemic diseases, use of aminoglycoside antibiotics, substance abuse, litigation regarding prior therapy, or other confounding conditions. Sixty-four injection sessions with completed with sixteen patients who were enrolled in the study and underwent EMG-guided incobotulinumtoxinA injections to the thyroarytenoid (TA) muscle using a hollow monopolar Teflon-coated needle via a trans-cricothyroid membrane approach. Dosages to each TA muscle were recorded and patients completed a Voice Handicap Index-10 (VHI-10), a validated worksheet regarding their perceived percent of normal function (PNF) following treatment, and a side effect profile. Outcomes were analyzed using the paired t-test.

[RESULTS] For primary transitioners to incobotulinimtoxinA, VHI-10 scores and best percent normal function did not significantly change. For non-responders, VHI-10 decreased from 32.5 on Botox to 19.5 on incobotulinimtoxinA and best PNF increased from 37.6 to 90 %, which was statistically significant. Transient side effects included breathiness.

[CONCLUSIONS] Our study demonstrates that incobotulinimtoxinA may be used successfully for adductor SD either as first line treatment or in secondary non-responders to onabotulinumtoxinA.