Etiology Unresolved middle ear infection 1. Uncomplicated inflammatory process of the middle ear may evolve over time to produce persistent effusion and irreversible mucosal change 2. Fluid contains enzymes to alter the mucosal lining of the middle ear, it results in collapse or chronic perforation 3. obstruction of narrow communication between the antrum and the attic the aditusEtiology ◼ Unresolved middle ear infection. 1. Uncomplicated inflammatory process of the middle ear may evolve over time to produce persistent effusion and irreversible mucosal change 2. Fluid contains enzymes to alter the mucosal lining of the middle ear, it results in collapse or chronic perforation 3. Obstruction of narrow communication between the antrum and the attic, the aditus