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Long-term therapy for spasmodic dysphonia: acoustic and aerodynamic outcomes
R P Mehta1, S N Goldman, L A Orloff
1Division of Otolaryngology, University of California, San Diego School of Medicine, 200 W Arbor Dr, San Diego, CA 92103-8891, USA.
Objective:
To evaluate the long-term aerodynamic, acoustic, and electromyographic effects of serial botulinum toxin (BT) injections in patients with adductor spasmodic dysphonia.
Design:
Two-year, nonrandomized, controlled, before-after study.
Setting:
Ambulatory care clinic at a single academic medical center.
Patients:
A convenience sample of 91 patients with adductor spasmodic dysphonia evaluated and treated during 2 years and 64 age- and sex-matched controls.
Interventions:
Injections of BT into the thyroarytenoid muscles in conjunction with electromyographic evaluation and acoustic and aerodynamic evaluation before and after serial BT injections.
Main Outcome Measures:
Translaryngeal airflow, jitter, shimmer, signal-to-noise ratio, fundamental frequency, standard deviation of fundamental frequency, maximum phonation time, and inappropriate muscle activity by electromyography.
Results:
Translaryngeal airflow, jitter, and shimmer improved significantly after serial BT treatments and showed sustained improvement over time. Fundamental frequency, standard deviation of fundamental frequency, and signal-to-noise ratio did not change significantly after BT treatment. Electromyographic data suggested decreased inappropriate muscle activity with repeated BT injections.
Conclusion:
Treatment with BT provides ongoing relief of voice perturbations in patients with adductor spasmodic dysphonia who undergo long-term cumulative therapy.