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Unmitigated negative nasopharyngeal pressure is associated with attic retraction pocket formation: LaPlace's law in action

Published online by Cambridge University Press:  11 October 2021

Nilesh H Mahajan
Affiliation:
Vijaya ENT Care Centre, Superspeciality Otology Centre, Bangalore560003, India
H Vijayendra*
Affiliation:
Vijaya ENT Care Centre, Superspeciality Otology Centre, Bangalore560003, India
Vinay Kumar Vijayendra
Affiliation:
Vijaya ENT Care Centre, Superspeciality Otology Centre, Bangalore560003, India
Miriam Redleaf
Affiliation:
Department of Otology-Neurotology, University of Illinois, Chicago Department of Neurosurgery, University of New Mexico, Albuquerque, USA
*
Author for correspondence: Dr Nilesh H Mahajan, Vijaya ENT Care Centre, Superspeciality Otology Centre, No. 1, 9th Cross, Malleshwaram, Bangalore560003, India E-mail : nilesh.virtual@gmail.com

Abstract

Background

Decades of clinical observation have led our subspecialty team to suspect that negative nasopharyngeal pressure is associated with attic retraction pocket formation. Furthermore, LaPlace's law, which states that the pressure within a sphere varies with the inverse of the radius, provides the dynamic explanation for why the attic area of the tympanic membrane tends to retract more frequently than the pars tensa.

Methods

The attic retraction pockets of 154 patients were classified into grades of severity (grades I–V). Impedance audiometry of middle-ear pressure was measured in the resting state, and after sniffing, swallowing and the Valsalva manoeuvre.

Results

Negative nasopharyngeal pressure (sniffing) caused a diminution of middle-ear pressure of −5 daPa on average in normal ears, and of −24 daPa to −45 daPa for tympanic membranes with attic retraction pockets of grade I to grade V.

Conclusion

Attic retraction pockets are associated with greater collapse of middle-ear volume when negative pressure is created in the nasopharynx. LaPlace's law, and the composition of the pars flaccida, suggests an explanation for why the attic region retracts more than the pars tensa.

Type
Main Articles
Copyright
Copyright © The Author(s), 2021. Published by Cambridge University Press

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Footnotes

Dr Nilesh H Mahajan takes responsibility for the integrity of the content of the paper

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