Classification of Inner Ear Malformations

Abstract

Morphologically congenital sensorineural hearing loss (SNHL) can be investigated under two categories. Majority of the congenital hearing loss (80 %) are membranous malformations. Here the pathology involves inner ear hair cells. There is no gross bony abnormality and, therefore, in these cases, high-resolution computerized tomography (HRCT) and magnetic resonance imaging (MRI) of the temporal bone revealed normal findings. The remaining 20 % have various malformations involving the bony labyrinth and, therefore, can be radiologically demonstrated by CT and MRI. The latter group involves surgical challenges as well as problems in decision-making. Some cases may be managed by hearing aid; some need cochlear implantation, while some cases are candidates for an auditory brainstem implantation. During cochlear implantation, there may be facial nerve abnormalities, cerebrospinal fluid leakage, electrode misplacement, or difficulty in finding the cochlea itself. During the surgery for inner ear malformations, the surgeon must be ready to modify the surgical approach or choose special electrodes for surgery.