Aerodynamic and acoustic parameters in CO2 laser posterior transverse cordotomy for bilateral vocal fold paralysis.

The aim of this prospective study was to analyse airway improvement and acoustic and aerodynamic parameters after CO2 laser posterior transverse cordotomy (LPTC) in bilateral vocal fold paralysis (BVFP). Four patients (2 males, 2 females) were recorded pre- and post-operatively at 1, 3, 6, 12 and 24 months. Forced inspiratory volume during the first second (FIV), vital capacity, peakflow, and forced expiratory volume during the first second (FEV) were measured with the Gould II spirometer. Acoustic frequency features (average fundamental frequency, standard deviation, jitter, shimmer and harmonic-to-noise ratio) and speech duration parameters (maximum phonation time, number of words read per minute, and number of words per breath) were measured. Aerodynamic parameters were measured with the Aerophone II. Three tasks were completed. Pneumo-phonatory parameters in "maximum sustained phonation" and in "comfortable phonation", and laryngeal aerodynamic parameters (intraoral air pressure, oral airflow and sound pressure level) were measured non-invasively. Glottal resistance and vocal efficiency were calculated. FIV increased significantly after LPTC (p = 0.01). Postoperatively, frequency features were undetectable by standard commercialized algorithms. Acoustic and aerodynamic parameters improved in the measures obtained at the 6th postoperative month. These results were stable 2 years postoperatively in all cases. We conclude that laryngeal aerodynamic parameters can be used objectively to follow patients longitudinally after LPTC.