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Abstract
Dysphagia following total laryngectomy has been attributed primarily to pharyngeal
dysfunction, but precise mechanisms underlying tracheoesophageal (TE) phonation are
unknown. The aims of this thesis were to investigate post-laryngectomy (1) pharyngeal
deglutitive biomechanics; (2) prevalence of oesophageal dysmotility and its relationship
with TE voice problems; and (3) mechanism of TE phonation.
Thirty-one total laryngectomees (1-12yrs prior) were recruited and stratified into severe
and 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. Oesophageal
HRM was assessed using the Chicago Classification v3.0. Inflow pressures were
calculated by vocalising during pharyngeal HRM with VF. Voice impairments were
evaluated using the Voice Symptom Scale (VoiSS-I). Measurements of voice quality and
energy were generated by Computerised Speech Lab. Endolumenal Functional Lumen
Imaging Probe accurately assessed minimal upper oesophageal sphincter (UOS)
diameters. A finite-element model was used to compare the influence of UOS radius and
inflow 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 to
correlate 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 voice
impairment (laryngectomees 35 ± 3 vs. healthy controls 16 ± 3, P < 0.0001). Both
experimental and modelling results demonstrated higher energy of TE phonation with
increased inflow pressure or UOS diameter.
In conclusion, detecting pharyngoesophageal junction resistance post-laryngectomy is
vital, as it correlates with dysphagia severity, is reversible, and can predict the response
to treatment. Peristaltic and LOS dysfunction is prevalent in this population. Sufficient
inflow pressure or a large UOS diameter is required for satisfactory TE phonation.