Effect of Thyroplasty on Laryngeal Airflow

Abstract

Thyroplasty has virtually replaced Teflon injection as the procedure of choice for treatment of the unilateral paralyzed vocal cord. Previous studies have shown that Teflon injection, by stiffening the vocal cord, decreases the extrathoracic airway obstruction occasionally measured by pulmonary function testing in patients with unilateral vocal cord paralysis. We became interested in the effect of thyroplasty on extrathoracic airflow. In this prospective study, patients underwent prethyroplasty and postthyroplasty pulmonary function testing. Flow volume loops combined with traditional spirometry were used. Postoperative pulmonary function tests were performed at least 2 months after surgery to allow resolution of surgical edema. Our study results support the previous finding that vocal cord paralysis alone causes some degree of extrathoracic obstruction. However, in contrast to Teflon injection, thyroplasty decreased extrathoracic airflow in all but 1 patient, and by criteria based on the ratio of the midexpiratory flow to the midinspiratory flow, caused new postoperative extrathoracic obstruction in 27% of patients. Symptomatic evidence of this obstruction may be more evident in those active patients with more ventilatory demand.

Changes in respiratory function after thyroplastic surgery

“…this increase remained within the normal range. In contrast, Janas et al reported significantly decreased values of inspiratory flow parameters after type I surgery [8]. They also reported a postoperative decrease of PEFR, although the decrease did not reach a significant level ( p 00.14).…”

“…Although UVFI in adult patients does not produce symptoms of laryngeal obstruction, Kashima [16] and Janas et al [8] reported that a certain number of patients with UVFI had signs of airway obstruction on respiratory function test. Kashima postulated that the flaccid vocal fold was drawn medially by the force of laryngeal airflow, resulting in greater turbulence and limitation of airflow [16].…”

“…Other authors also used a ratio of V E50 to V I50 because obstruction at the laryngeal level commonly affects the inspiratory phase of the flow-volume loop more than the expiratory phase [8,11]. However, flow-volume loop examination in the inspiratory phase is not performed at the Pulmonary Center of Kumamoto University Hospital due to high variability in the results obtained during inhalation compared with that during expiration in each patient.…”

“…As far as we are aware, there is no published report yet of respiratory function after implementation of AA or AA combined with a method for augmentation. Only Janas et al reported the respiratory function of two patients who underwent AA together with type I and cricothyroidpexy (type IV thyroplasty) [8]. One of them showed an increase of V E50 /V I50, from 1.23 preoperatively to 2.33 postoperatively.…”

Beeinträchtigung der Lebensqualität bei Patienten mit einseitiger Rekurrensparese nach thoraxchirurgischen Eingriffen

“…In früheren Studien zeigten quantitative Messungen (Stimmfeldmessung, s/z Ratio, auditive Stimmklangbeurteilung und Lungenfunktionsmessung) verbesserte Stimmleistungen nach operativer Stimmlippenmedialisation [12,15,24,25,26].…”