The attic block syndrome

Abstract

Although the true reason for pneumatization of the mastoid bone is not known, there are some theoretical benefits. As with the other pneumatized areas of the skull (ie, paranasal sinuses), aeration may be a benefit simply by decreasing the overall weight of the bony skull. Physiologically, the mastoid may be a way of increasing the effective volume of the middle ear. The greater the gaseous volume, the greater the compliance and the greater the ability to tolerate changes in middle ear pressure. Additionally, the volume of the middle ear/ mastoid complex affects the resonance properties of the ear. The larger the volume, the lower the resonance frequency. On the other hand, the honeycomb nature of the mastoid is felt to dampen the resonant peaks because the cavity is broken up into smaller individual air cells.1 The pneumatization of the middle ear is known to begin at approximately the eighth week of fetal life. The extension of aeration into the mastoid antrum area also begins at this time. Mastoid aeration progresses to its maximum by the age of 10 years in females and 15 years in males. Aeration of the pneumatized mastoid depends on a functioning eustachian tube and a patent middle ear space. Obstruction between the mastoid and the eustachian tube prevents normal air exchange and basic physiological function. The predominant venue of air flow between the middle ear and the mastoid is through the antrum and the epi tympanum (or attic) adjacent to the heads of the ossicles. In a sense, the heads of the ossicles partially obstruct the epitympanum. This narrow passage is further compromised by the numerous thin mucosal folds crisscrossing this area as described by Proctor. 2 Inflammatory processes such as infection can frequently lead to thickening of the normally thin mucous membrane of the middle ear and mastoid. If the thickening is severe enough, the mastoid antrum and/or epitympanum can be completely obstructed, leading to isolation of the mastoid air system. The ossicular heads and the many mucosal folds in the epitympanum put the attic at high risk for obstruction. This blockage is likely a frequent reversible occurrence, and temporary obstruction may create no significant or permanent problems. Treatment of the inflammatory process should lead to reversal of the mucosal thickening and resumption of aeration. At times the process reaches an irreversible state. There are several possible reasons for the lack of resolu-