Hearing loss.

Nearly 30 million Americans have hearing loss. Audiograms are used to determine if hearing loss is sensorineural (SNHL), conductive (CHL), or mixed (MHL). SNHL indicates dysfunction of the cochlea, cochlear nerve, or brain. The study of choice for adults with SNHL is gadolinium-enhanced magnetic resonance imaging, which is used to look for acoustic neuromas, abnormal labyrinth signal intensity or enhancement, and brain disease. In children with SNHL, computed tomography (CT) performed with bone algorithms demonstrates inner ear dysplasias. SNHL from trauma is best evaluated with CT studies. CHL indicates disease in the external auditory canal, tympanic membrane, or middle ear; CT with thin bone algorithms is the best study. Causes of CHL include external canal atresia and neoplasms, myringosclerosis, middle ear anomalies, effusion, cholesteatomas, and neoplasms. MHL is a combination of SNHL and CHL. Dysplasias such as otosclerosis and osteogenesis imperfecta, the most frequent diseases with radiologic findings, are best assessed on CT images. The combination of patient age and type of hearing loss determines the best imaging study.