Measurement of laryngeal resistance in the evaluation of botulinum toxin injection for treatment of focal laryngeal dystonia.

In the past, there has been no consistent, objective method of following patients undergoing botulinum toxin injections for treatment of laryngeal dystonia. Herein, the application of translaryngeal resistance measurements to 15 dysphonic patients is described. Laryngeal resistance is calculated from analysis of translaryngeal pressure and airflow during the utterance /pi/, and found to fall predictably after successful toxin injection. In our series of patients, laryngeal resistance dropped by 69.1% after initial toxin injection. The changes in resistance over time correlate with subjective impressions of voice quality. Translaryngeal resistance measurements can be used objectively to follow patients longitudinally after injection and to collect objective data for analysis. No previously described measurements have met all these criteria. Laryngeal resistance measurement is an ideal method of documenting the results of botulinum toxin injection for the treatment of focal laryngeal dystonia.