CT and MR Imaging of the Inner Ear and Brain in Children with Congenital Sensorineural Hearing Loss

Abstract

Imaging plays an important role in the evaluation of congenital sensorineural hearing loss. In children who are candidates for cochlear implantation surgery, it provides vital preoperative information about the inner ear, the vestibulocochlear nerve, and the brain. High-resolution computed tomography (CT) and magnetic resonance (MR) imaging provide excellent delineation of the intricate anatomy of the inner ear: CT depicts the minute details of osseous structures, and MR imaging allows visualization of the fluid-filled spaces and the vestibulocochlear nerve. Together, these complementary modalities can aid decision making about the best management strategy by facilitating the identification and characterization of inner ear malformations and any associated neurologic abnormalities. It is important that the radiologist be familiar with the key imaging features when interpreting CT and MR images obtained in this patient group. A broad spectrum of inner ear malformations have been described and linked to developmental insults at different stages of embryogenesis, and various systems have been proposed for classifying them. In this article, these malformations are described by using classification systems used by otolaryngologists for ease of interpretation. The relevant normal anatomy and development of the inner ear are briefly surveyed, standard imaging protocols for studying the inner ear are reviewed, and the imaging appearances of frequently observed inner ear malformations are described and illustrated. The impact of the identification of these malformations and commonly associated brain abnormalities on clinical management and prognosis also is discussed.

The Isolated Vestibular Anomaly with Normal Cochlea: An Analysis of Radiologic and Clinical Findings

“…By the 8 th week, the development weeks; the lateral canal or duct is the last to form. Ossification of the labyrinth is complete by the 23 rd week [1] . The LSC is the last complete ossification among the SCs and is the most susceptible to anomalous development.…”

“…Disturbance of normal fusion and ossification may lead to a short LSC complex or to a persistent anlage of the LSC, with the lack of a central ossified bony island [4] . Vestibular malformations rarely occur in isolation [1] . Several terms to describe vestibular malformation, such as dysplastic, dilated, or enlarged vestibular anomalies are found in the literature.…”

“…The vestibular system comprises the vestibule, with the saccule and utricle, and three semicircular canals (SCs; lateral, posterior, and superior), which are oriented perpendicularly to each other [1] .…”

Mri and High Resolution Ct in Congenital Hearing Loss

“…Joshi et al, 2012 (6) Clear understanding of the embryogenesis and anatomy of the external, middle and inner ear and the standard classification systems for describing inner ear malformations are fundamental to the interpretation of CT and MR. Identification of the ear abnormality has a substantial effect on clinical decision making, prognosis, and management strategy.…”

“…The additional acquisition of axial T2-weighted MR images of the brain during imaging of the inner ear allows the identification of brain abnormalities that commonly coexist with congenital inner ear malformations (6) .…”