Transient hypopharyngeal intrabolus pressurization patterns: Clinically relevant or normal variant?

Introduction: In oropharyngeal dysphagia, impaired pharyngoesophageal junction (PEJ) opening is reflected by an elevated hypopharyngeal intrabolus pressure (IBP), quantifiable using pharyngeal high-resolution manometry with impedance (P-HRM-I). Transient intrabolus pressurization (TP) phenomena are not sustained and last for only a brief period. We hypothesized that TP patterns reflect impaired coordination between timing of hypopharyngeal bolus arrival and PEJ relaxation.

Methods: A retrospective audit was conducted of P-HRM-I datasets; 93 asymptomatic Controls and 214 Patients with differing etiological/clinical backgrounds were included. TP patterns were examined during 10ml liquid swallows. TP was defined by a simultaneous, non-sustained, pressurization wave spanning from the velo-/meso-pharynx to PEJ. The coordination between deglutitive pharyngeal bolus distension and PEJ relaxation timing was assessed using timing variables; (i) Distention-Contraction Latency (DCL, s) and (ii) PEJ Relaxation Time (RT, s). Resultant flow resistance was quantified (IBP, mmHg).

Results: TP swallows were observed in 87 (28%) cases. DCL was not significantly different in relation to TP, while PEJ relaxation time was shorter, and IBP was higher during TP swallows. In Patients RT-DCL time difference correlated with IBP (r -0.368, p < 0.01).

Conclusion: Bolus distension and PEJ relaxation were miss-timed during TP swallows, impeding bolus flow and leading to a brief period of pressurization of the pharyngeal chamber by muscular propulsive forces. While TP swallows were identified in both Controls and Patients, increased IBPs were most apparent for Patient swallows indicating that the extent of IBP increase may differentiate pathological TP swallows.