Effects of surgery on the relationship between subglottic pressure and fundamental frequency in vocal fold dynamics in patients with benign laryngeal diseases.

Purpose: Subglottic pressure (P) and fundamental frequency (F) play important roles in governing vocal fold (VF) dynamics. Theoretical description, model simulation, excised larynx and animal models have been used in previous studies, yet clinically applicable measurements are still lacking. This study aimed to evaluate the effects of surgery for benign laryngeal lesions by investigating the relationship between F and P.

Methods: Patients with benign laryngeal lesions who underwent phonosurgery were prospectively recruited. Participants were instructed to sustain voicing the vowel /o/ at three incremental frequencies four semitones apart in the modal register (F01, F02, F03). F was estimated by VF vibration on the accelerometer. P change was achieved and measured using the airflow interruption method.

Results: Thirteen patients with a mean age (SD) of 43.5 (12.4) years were included. The change in F per unit change of P, which is the slope (Hz/kPa) of the regression line of the frequency-pressure data pairs, decreased as the tension of the VF increased. The slopes significantly increased after the operation for F01 and F02 (36.43 ± 14.68 preoperatively, 53.91 ± 30.71 postoperatively, p = 0.011 and 26.02 ± 10.71; 34.85 ± 17.92, p = 0.046, respectively). In addition, there was a significant decrease in phonation threshold pressure and improvements in the grade, roughness, breathiness, asthenia, strain scale, and the voice handicap inventory-10.

Conclusions: The relationship between F and P may serve as an objective assessment of the outcomes in the treatment of benign laryngeal diseases with clinical relevance.