Epitympanic compartment surgical considerations: reevaluation.

The epitympanic compartments and the anatomy of the atticotympanic diaphragm were examined in a pair of serially sectioned temporal bones with secretory otitis media and chronic otitis media, respectively. Findings confirmed reports of 19th century scientists in that Prussak's space has a wide connection to the mesotympanum through the posterior pouch of Tröltsch and may have an additional narrow passage in its roof to the lateral malleal space. The lateral incudomalleal fold regularly separates the upper lateral attic from the lower lateral attic and the mesotympanum. The medial incudal fold as a rule is atrophic already at birth. The anterior tympanic isthmus thus extends from the tensor tympani tendon to the posterior incudal ligament and is the main passage for epitympanic and mastoid aeration. Opening(s) in the tensor fold, when present, are also important. In some ears, the posterior tympanic isthmus may form an auxiliary narrow route for aeration via the incudal fossa. The isthmi may be blocked by middle ear infection, which can lead to chronic mastoid and attic disease. Pathways for cholesteatoma spread in the epitympanum are discussed.