Localized middle ear effusions: three unusual acute cases in adults.

Three cases of acute, non-suppurative otitis media in adults are described. They are unusual in that the effusion was confined to the upper middle ear, whilst the lower middle ear was aerated. The aetiology of such localized effusions, is probably related to the anatomy of the middle ear compartments, the mucosal folds forming them and the apertures allowing communication between them. The compartments are relatively constant and are a result of the embryological development of the middle ear. The localization of these effusions, demonstrates the segmental anatomy of the middle ear.