Otites moyennes chroniques. Histoire élémentaire et formes cliniques

Chronic otitis media (COM), usually defined as a prolonged inflammation of the middle ear cavities, has several clinical presentations. Each corresponds to a pathological process characterized by irreversible anatomical and histological lesions, by specific symptoms and otoscopic features, as well as by its evolution. The pathogenic process that leads to these different types remains insufficiently known. It induces a dysfunction of the numerous embryological, anatomical, histological and immunological factors that are involved in the regulation of the middle ear physiology. The different types share an initial inflammation and/or infection occurring most of the time in early childhood. The mechanisms responsible for the evolution towards the various forms are still uncertain. The study of their natural history suggests that each type is related to a distinct path. The COM is therefore a generic term that covers at least five different entities which may be distinguished by repeated and careful otoscopies : i) serous otitis or secretory otitis media, is almost constant during childhood, sometimes complicated by a bacterial infection; it produces an effusion indicating a mucous metaplasia which is due to a sustained inflammation of the middle ear, itself a consequence of an acute otitis media or an airway infection. Most frequently, these episodes have a favourable outcome, but could, although this is very controversial, induce the transformation towards the other types of COM; ii) open chronic mucosal otitis, a typical COM, may be complicated by an osteitis, a squamous and/or mucous metaplasia, or mallear epidermosis. These may leave anatomical or functional sequelae, with or without tympanosclerosis; iii) adhesive otitis is the consequence of a connective tissue pathology, which is probably due to severe childhood mucosal otitis media, leading to a symphysis of the mesotympanum; iv) atelectatic otitis is the result of middle ear ventilation pathology acting on a fragile tympanic membrane; when eccentric, it realizes a retraction pocket which preludes to the development of the last entity; v) the cholesteatoma which is the most dangerous variety due to its osteolytic and extensive properties. As a conclusion, the COM is not a unique entity and it is therefore important to establish the distinction between its different clinical presentations, since each has its own history and necessitates specific therapeutic management.