Anatomic Malformations of the Middle and Inner Ear in 22q11.2 Deletion Syndrome: Case Series and Literature Review

Abstract

Background and purpose: The 22q11.2 deletion syndrome is characterized by a heterogenic phenotype, including hearing loss. The underlying cause of hearing loss, especially sensorineural hearing loss, is not yet clear. Therefore, our objective was to describe anatomic malformations in the middle and inner ear in patients with 22q11.2 deletion syndrome.

Materials and methods: A retrospective case series was conducted in 2 tertiary referral centers. All patients with 22q11.2 deletion syndrome who had undergone CT or MR imaging of the temporal bones were included. Radiologic images were evaluated on predetermined parameters, including abnormalities of the ossicular chain, cochlea, semicircular canals, and vestibule.

Results: There were 26 patients (52 ears) with a CT or MR imaging scan available. A dense stapes superstructure was found in 18 ears (36%), an incomplete partition type II was suspected in 12 cochleas (23%), the lateral semicircular canal was malformed with a small bony island in 17 ears (33%), and the lateral semicircular canal and vestibule were fused to a single cavity in 15 ears (29%).

Conclusions: Middle and inner ear abnormalities were frequently encountered in our cohort, including malformations of the lateral semicircular canal.

Fig 1.

Radiologic malformations of the middle and inner ear encountered in 52 ears.

Fig 2.

A, Axial CT image of the left mastoid shows a normal stapes superstructure for comparison with B. B, Axial CT image of the right mastoid shows a dense, thick stapes superstructure. The pure tone audiogram of this patient is shown in Fig 5B. The mastoid bones shown in A and B do not belong to the same patient.

Fig 3.

A, Axial CT image of the right mastoid shows an incomplete partition type II of the cochlea. The basal turn (BT) of the cochlea is intact; the apical and middle turn (A/M) seem confluent. B, A pure tone audiogram of the same ear shows normal hearing. The circle indicates an unmasked air-conduction threshold; the bracket, a masked bone-conduction threshold.

Fig 4.

A, Axial CT image of left mastoid bone shows the lateral semicircular canal with a small bony island. B, A pure tone audiogram of the same ear shows a mild conductive hearing loss. The x indicates an unmasked air-conduction threshold; the bracket, a masked bone-conduction threshold.

Fig 5.

A, Axial CT image of the right mastoid bone. The bony island of the lateral semicircular canal is missing, and the canal and vestibule are composed of a single cavity (SC). B, A pure tone audiogram of the same ear shows conductive hearing loss, more pronounced in the low frequencies. The circle indicates an unmasked air-conduction threshold; the bracket, a masked bone-conduction threshold.

Fig 6.

Axial CT image of the right mastoid bone showing a carotid canal dehiscence (C).