[Dural bone defects and encephalocele associated with chronic otitis media or its surgery].

OBJECTIVES: We investigated the incidence of dural bone defects and encephalocele following radical mastoidectomy or open cavity tympanoplasty. PATIENTS AND METHODS: We retrospectively evaluated 190 operations of 182 patients (97 males, 85 females; mean age 30.6 years; range 9 to 70 years) who underwent radical mastoidectomy (n=89) or open cavity tympanoplasty (n=101). Follow-up examinations included otomicroscopy. Patients with documented dural bone defects on examination or operation records were further evaluated by axial and coronal computed tomography scans of the temporal bone. Those with suspected encephalocele were studied by magnetic resonance imaging.
RESULTS: Dural bone defects were detected in 17 patients perioperatively. Of these, 14 defects were associated with chronic otitis media. Three iatrogenic bone defects were induced during obliteration of lateral sinus thrombosis. The mastoid tegmen was the most common site of defects (41%) and the most common etiologic factor was cholesteatoma (84%). Encephalocele was detected in one patient in whom radical mastoidectomy with lateral sinus obliteration was performed due to lateral sinus thrombophlebitis. Encephalomalasia was found nearby the defect area in two patients.
CONCLUSION: Dural bone defects associated with chronic otitis media are not rare, the most common cause being cholesteatoma. Repair of dural lacerations requires watertight closure to prevent the occurrence of encephalocele.