THE PARS FLACCIDA MIDDLE-EAR PRESSURE AND MASTOID PNEUMATIZATION INDEX

The degree of pars flaccida retraction and the levels of mastoid pneum atization were assessed and correlated in 388 adults with intact pars tensa. Poorly pneumatized mastoids were found to be associated with re traction of pars flaccida; the poorer the pneumatization, the deeper t he retraction. Well pneumatized mastoids were usually associated with normal position of the pars flaccida. The pars flaccida was previously also shown to retract in face of ME negative pressure-and its degree can be seen to be an index of ME negative pressure. Thus, the correlat ion of deeper degrees of pars flaccida retractions with mastoid hypopn eumatization (and vice versa) lends strength to the studies which show the mastoid pneumatic system to have a function of a passive ME press ure buffer. This observation lends further evidence as to why ears wit h poorly pneumatized mastoids are a priori at risk to develop complica tions such as SOM in adults, tympanic membrane retractions and perfora tions, incus necrosis or retraction pocket cholesteatoma. Ears with a large pneumatic system are hardly at such risk.