[Clinical features of congenitally enlarged bony portion of Eustachian tube]

Objective:To investigate the clinical features of patients with congenitally enlarged bony portions of the Eustachian tube（ET）. Methods:The medical history, physical examination, hearing test, temporal bone high resolution computed tomography（HRCT） of six patients（nine ears） with congenitally enlarged bony portion of the ET were retrospectively analyzed. Results:Four patients were men and two were women. The minimum, maximum, and average ages were 5, 21, and（14.7±6.4） years, respectively. Three malformations were bilateral and three were left-sided. Three ears had conductive hearing loss（average bone and air conduction thresholds were 13.7 dB and 71.3 dB）, three had mixed hearing loss（average bone and air conduction thresholds were 27.7 dB and 83.7 dB）, and one had extremely severe sensorineural hearing loss. The average maximum length and width of the enlarged bony ET on temporal bone HRCT were（22.61±2.94） mm and（6.50±2.33） mm, respectively. The enlargement was combined with an external auditory canal malformation in six ears, narrow tympanic cavity in six, tympanic antrum malformation in five, ossicular chain malformation in seven, cochlear malformation in six, helicotrema malformation in three, vestibule widening in two, semicircular canal malformation in three, vestibular window malformation in six, facial nerve abnormality in five, internal auditory meatus malformation in two, low middle cranial fossa in eight, and severe internal carotid artery malformation in one. Conclusion:Bony ET enlargement is a rare congenital middle ear malformation which could combined with other ear malformations. Patients can have no ET dysfunction but different patterns of hearing loss. The defect is usually found unintentionally during imaging, and the HRCT of temporal bone is significant.