Malformations of the middle and inner ear on CT imaging in 22q11 deletion syndrome

Abstract

The 22q11 deletion syndrome (22q11DS), the most frequent microdeletion syndrome in humans, presents with a large variety of abnormalities. A common abnormality is hearing impairment. The exact pathophysiological explanation of the observed hearing loss remains largely unknown. The aim of this study was to analyze the middle and inner ear malformations as seen on computer tomographic imaging in patients with 22q11DS. We retrospectively reviewed the charts of 11 22q11DS patients who had undergone a CT of the temporal bone in the past. Of the 22 examined ears, two showed an abnormal malleus and incus, 10 presented with a dense stapes superstructure, and three ears had an abnormal orientation of the stapes. With regard to the inner ear, 12 ears showed an incomplete partition type II with a normal vestibular aqueduct. In four ears the vestibule and lateral semicircular canal were composed of a single cavity, in 14 ears the vestibule was too wide, and three ears had a broadened lateral semicircular canal. These findings suggest that malformations of the stapes, cochlea, vestibule, and lateral semicircular canal are frequent in 22q11DS. To our knowledge, the current study involves the largest case series describing middle and inner ear malformations in 22q11DS. © 2016 Wiley Periodicals, Inc.

Prevalence of hearing loss and clinical otologic manifestations in patients with 22q11.2 deletion syndrome: A literature review

“…This latter malformation was suggested not to arise from recurrent middle ear infections, as one patient showed to have this abnormality at only 9 days of age. Furthermore, they reported on a larger basal turn of the cochlea in two ears and an incomplete partition in 12 ears (55%) . Ossicular chain abnormalities are also reported by Solot et al, Jiramongkolchai et al and Persson et al (although these studies were included in this review, these data were not), and they described a total of eight patients with ossicular chain malformations.…”

“…The conductive hearing loss in 22q11DS patients is presumably to a large extent caused by otitis media and consequences thereof such as a perforation of the tympanic membrane . However, there are also case reports and one radiologic study describing middle ear malformation, including a dens stapes superstructure, that might result in conductive hearing loss . There are a few hypothesis regarding potential causes of sensorineural hearing loss in patients with 22q11DS.…”

“…Some authors speculate on cochlear damage secondary to vascular damage or recurrent otitis media, others reported on patients with anatomical malformations of the inner ear . Recently, a retrospective radiologic study analysed the CT scans of the temporal bone in 11 patients with 22q11DS and found an incomplete partition type II of the cochlea in 55% of the analysed ears …”

“…[8][9][10][11][12] However, there are also case reports and one radiologic study describing middle ear malformation, including a dens stapes superstructure, that might result in conductive hearing loss. [13][14][15] There are a few hypothesis regarding potential causes of sensorineural hearing loss in patients with 22q11DS. Some authors speculate on cochlear damage secondary to vascular damage or recurrent otitis media, 16,17 others reported on patients with anatomical malformations of the inner ear.…”

“…13 Recently, a retrospective radiologic study analysed the CT scans of the temporal bone in 11 patients with 22q11DS and found an incomplete partition type II of the cochlea in 55% of the analysed ears. 15 In addition, Tbx1 is identified as a candidate gene responsible for ear abnormalities in mouse models. [18][19][20] In mice, inactivation of the Tbx1 gene in the otic vesicle leads to disruption of inner ear development.…”