Pediatric sensorineural hearing loss, part 1: Practical aspects for neuroradiologists

Abstract

SNHL is a major cause of childhood disability worldwide, affecting 6 in 1000 children. For children with prelingual hearing loss, early diagnosis and treatment is critical to optimizing speech and language development, academic achievement, and social and emotional development. Cross-sectional imaging has come to play an important role in the evaluation of children with SNHL because otolaryngologists routinely order either CT or MR imaging to assess the anatomy of the inner ears, to identify causes of hearing loss, and to provide prognostic information related to potential treatments. In this article, which is the first in a 2-part series, we describe the basic clinical approach to imaging of children with SNHL, including the utility of CT and MR imaging of the temporal bones; we review the most recent proposed classification of inner ear malformations; and we discuss nonsyndromic congenital causes of childhood SNHL.

Fig 1.

Labyrinthine aplasia. Axial (A) and coronal (B) right temporal bone CT images demonstrate the complete absence of normal inner ear structures. Notice the diminished size of the inner ear edifice and absence of a well-formed internal auditory canal, which help to distinguish this from labyrinthitis ossificans.

Fig 2.

IP-II. Axial CT (A) and CISS (B) images through the right temporal bone demonstrate cochlear dysplasia with a deficient modiolus and fusion of the middle and apical turns, resulting in a bulbous-appearing cochlear apex. The vestibule and semicircular canals are normal, and the vestibular aqueduct is not enlarged.

Fig 3.

Cochlear aplasia. Axial CT image through the right temporal bone demonstrates a dysplastic vestibule fused to an abnormal lateral SCC, with absence of the cochlea. Notice the small canal for the vestibular nerve (arrow).

Fig 4.

Common cavity deformity. Axial CT (A) and CISS (B) images through the left inner ear demonstrate an enlarged cystic cavity representing the cochlea and vestibule without differentiation.

Fig 5.

Cystic cochleovestibular anomaly (IP-I). Axial CT (A) and CISS (B) images through the right temporal bone demonstrate a cystic-appearing and featureless cochlea and vestibule. The cochlea and vestibule form a “figure 8” or “snowman” contour, with slightly increased separation compared with the common cavity deformity demonstrated in Fig 4.

Fig 6.

Cochlear hypoplasia. Axial CT (A) and FSE T2-weighted (B) images through the left temporal bone demonstrate a small cochlea, resembling a bud off of the IAC. The vestibule is also enlarged and dysplastic and is fused with a pocketlike lateral SCC.

Fig 7.

Enlarged vestibular aqueduct. A, Axial CT image through the right temporal bone demonstrates enlargement of the vestibular aqueduct, which has a fanlike configuration (arrow). Notice how the width of the aqueduct at its midpoint is larger than that of the adjacent SCCs. The cochlea is also mildly dysplastic (IP-II). B, Axial CISS image through the left temporal bone in a different patient demonstrates marked enlargement of the endolymphatic duct and sac (asterisk).

Fig 8.

Lateral SCC dysplasia. Axial (A) and coronal (B) right temporal bone images demonstrate a dysplastic pocketlike lateral SCC, which is fused to the vestibule and missing its central bony island. On the coronal image, the lateral SCC is truncated. Both the superior and posterior SCCs are present.

Fig 9.

SCC dysplasia with a small lateral SCC bony island. The transverse diameter of the lateral SCC (double arrow) only measures 1.9 mm (normal, 2.6–4.8 mm). The vestibule is also enlarged and dysplastic, and the cochlea is hypoplastic.

Fig 10.

Cochlear nerve deficiency. A, Reconstructed sagittal CISS image through the right IAC demonstrates the absence of the right cochlear nerve. B, Compare with the sagittal image through the normal left IAC.

Fig 11.

Bony cochlear nerve canal atresia in a patient with CND. A, Axial CT image through the right temporal bone of the same patient shown in Fig 10 demonstrates an atretic canal for the cochlear nerve at the base of the cochlea. B, Compare A with the normal-caliber BCNC on the left.