Table 3. Causes of the obstructive eustachian tube dysfunction

Functional obstruction	ChildrenCleft palate
Anatomical obstruction	Nasopharyngeal tumorAdenoid hypertrophySinusitisUpper airway infectionAllergyGastroesophageal reflux disease, GERDCholesteatoma or dermoid cystRadiation therapyAcquired eustachian tube stricture due to eustachian tube damage (Cleft palate surgery or L-tube insertion)Congenital eustachian tube stenosis due to craniofacial anomaliesDown syndromeCrouzon syndromeApert syndromeTreacher-Collins syndromeTurner syndrome
Dynamic dysfunction (muscular failure)	Myasthenia gravis