The most widely accepted theory of acquired cholesteatoma pathogenesis is the retraction pocket theory. The negative middle ear pressure responsible for pars flaccida retraction is primarily caused by:

• A Excessive mucociliary activity creating a 'suction' effect on the tympanic membrane
• B Mastoid hypopneumatisation with increased oxygen absorption from the closed cavity
• C Chronic Eustachian tube dysfunction preventing middle ear pressure equalisation with atmospheric pressure ✓
• D Tensor tympani hyperactivity pulling the membrane inward

Explanation

Chronic Eustachian tube dysfunction impairs the ability to equalise middle ear pressure with atmospheric pressure during swallowing and yawning. This leads to persistent negative middle ear pressure, which draws the poorly supported pars flaccida (Shrapnell's membrane) inward to create a retraction pocket. Progressive deepening of this pocket into the epitympanum, combined with accumulation of desquamating keratin, forms the cholesteatoma. Mastoid hypopneumatisation may further perpetuate negative pressure but is secondary to ET dysfunction.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.