Janice D. Janas, MD, Al Hillel, MD

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 cord, decreases the extrathoracic airway obstruction occasionally seen in these patients. 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 and maximum voluntary ventilation 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 extrathoracic obstruction in some patients. However, in contrast to the Teflon literature, our study found that thyroplasty can cause extrathoracic obstruction in up to one third of patients. Symptomatic evidence of this obstruction may be more evident in active patients.