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.
RSNA, 2012