[Agenesis of the ear: analytical study. Apropos of 150 cases].

Congenital malformations and agenesis of the ear can affect the external and middle ears, while internal ear structures are generally spared. The malformations may be of different degrees but two stages are usually distinguished. Major agenesis involves malformations of the pinna with absence of the canal and severe middle ear lesions, while in minor agenesis the external ear is only slightly affected or is normal, but is associated with malformations of the auditory ossicula and the walls of the tympanic cavity. The difficulty in deciding on therapy and the extreme variability of results from one case to another explains the wide divergence of opinions of different authors. Three factors are of importance to ensure effective treatment : as early as possible detection, determination of suitability for operation by a complete investigation, and language teaching, a major problem in bilateral agenesis, by means of a hearing-aid initially, followed by surgery.