The Function of Deglutition and Phonation following Total Laryngectomy

Dysphagia following total laryngectomy has been attributed primarily to pharyngealdysfunction, but precise mechanisms underlying tracheoesophageal (TE) phonation areunknown. The aims of this thesis were to investigate post-laryngectomy (1) pharyngealdeglutitive biomechanics; (2) prevalence of oesophageal dysmotility and its relationshipwith TE voice problems; and (3) mechanism of TE phonation.Thirty-one total laryngectomees (1-12yrs prior) were recruited and stratified into severeand mild/nil (Sydney Swallow Questionnaire < 500) pharyngeal dysphagia.Hypopharyngeal intrabolus pressure (hIBP) was measured by high resolution manometry(HRM) with concurrent videofluoroscopy (VF), and repeated postdilatation. OesophagealHRM was assessed using the Chicago Classification v3.0. Inflow pressures werecalculated by vocalising during pharyngeal HRM with VF. Voice impairments wereevaluated using the Voice Symptom Scale (VoiSS-I). Measurements of voice quality andenergy were generated by Computerised Speech Lab. Endolumenal Functional LumenImaging Probe accurately assessed minimal upper oesophageal sphincter (UOS)diameters. A finite-element model was used to compare the influence of UOS radius andinflow pressure on TE phonation.hIBP was found to be higher in severe than in mild/nil dysphagia subjects (41 ± 10 vs. 13± 3 mmHg; P = 0.02). Predilation hIBP (R^2 = 0.97) and its postdilatation decrement (R^2= 0.98) predicted symptomatic improvement. Oesophageal dysmotility patterns included:achalasia; oesophagogastric junction outflow obstruction; diffuse oesophageal spasm;other major (30%) and minor (50%) peristaltic disorders. No specific pattern appeared tocorrelate with voice problems. Reduced voice quality (laryngectomees 1.86 ± 0.4 dB;healthy aged female: 10.93 ± 0.27 dB; healthy aged male: 12.55 ± 0.33 dB; both P <0.0001) and energy (R^2 = 0.35; P = 0.045) were important factors contributing to voiceimpairment (laryngectomees 35 ± 3 vs. healthy controls 16 ± 3, P < 0.0001). Bothexperimental and modelling results demonstrated higher energy of TE phonation withincreased inflow pressure or UOS diameter.In conclusion, detecting pharyngoesophageal junction resistance post-laryngectomy isvital, as it correlates with dysphagia severity, is reversible, and can predict the responseto treatment. Peristaltic and LOS dysfunction is prevalent in this population. Sufficientinflow pressure or a large UOS diameter is required for satisfactory TE phonation