Modeling of pharyngoesophageal segment during tracheoesophageal phonation in total laryngectomy patients with preliminary validation

Abstract

For patients with large or recurrent laryngeal cancer, total laryngectomy surgery is usually performed. In the absence of a larynx, tracheoesophageal (TE) voice is the gold standard for alaryngeal phonation. The mechanisms underlying TE voice are unknown, but pharyngoesophageal (PE) segment vibration has been shown to play a key role. The aim of this study was to systematically explore the mechanics of PE segment vibration during TE phonation. A 2D axisymmetric finite-element model with two domains representing the air and PE wall was developed. Comparison was made between models with different upper esophageal sphincter (UES) radius, and with different inflow pressures. The TE voice of total laryngectomy patients was assessed using Voice Symptoms Scale and VisiPitch recording. PE segment vibration and pressure gradient (ΔP) were measured using High Resolution Manometry with concurrent video-fluoroscopy. Simulation results revealed two different resonant frequencies, with maximal displacement at high frequencies increasing towards the UES. UES displacement increased with increased inflow pressure or UES diameter. Patient studies revealed that the location of maximal PE segment vibration ranged between the fourth and sixth cervical vertebrae. Average AP varied from 11-68 mmHg during phonation among subjects, and consistent with our simulation results, patients with higher AP reported a lower score on the voice symptom scale. The fundamental frequency determined from TE voice recordings corresponded with the computer simulations (209±67 Hz).