MECHANISM OF TRACHEOESOPHAGEAL SHUNT PHONATION

Objective: To elucidate the phonatory mechanism of tracheoesophageal shunt speech after total laryngectomy, we examined the dynamics and origin of neoglottis in tracheoesophageal shunt speakers. Design: We conducted the videofluoroscopic, strobofiberscopic, and electromyographic studies of the pharyngoesophageal segment in tracheoesophageal shunt phonation. Setting: Academic referral medical center. Patients: Twenty-five tracheoesophageal shunt speakers were examined. Results: Videofluoroscopic and fiberscopic examinations showed two bulges in the pharyngeoesophageal segment. The upper bulge was revealed to be the. sound source of tracheoesophageal shunt speech by the stroboscopic examination; anteroposterior and undulating regular movements were observed. Electromyographic study elucidated the contribution of muscle contraction to the two bulges; the upper bulge is formed by the thyropharyngeal muscle, whereas the lower bulge corresponds to the cricopharyngeal muscle. Conclusion: The neoglottis was considered to be formed by the stenotic portion due to thyropharyngeal muscle contraction and mucosal vibration due to expiratory airflow. This new understanding of the phonatory mechanism will be indispensable in the treatment of cases with failing shunt speech.