Meningo-encephalocoele of the temporal bone, also known as fungus cerebri, is a rare occurrence in clinical practice. We present a series of 13 patients with chronic otitis media who suffered brain herniation into the mastoid cavity. We also discuss the presentation and management of brain herniation with or without cerebrospinal fluid leak.
Among 963 cases undergoing revision mastoid surgery, 13 patients suffered brain herniation. These cases were identified and analysed.
All 13 patients' initial diagnosis was chronic suppurative otitis media with cholesteatoma, and all had undergone previous mastoid surgery resulting in a defect in the tegmen and weakening of the dura mater. The revision procedures performed included 10 (76.9 per cent) modified radical mastoidectomies without ossicular chain reconstruction and one (7.6 per cent) modified radical mastoidectomy with ossicular chain reconstruction; two (15.3 per cent) patients required a blind sac closure. Brain herniation and/or cerebrospinal fluid leak were repaired by a transmastoid ± minicraniotomy procedure.
Injury to the tegmen and dura should be avoided during surgery for chronic middle-ear disease. Cerebrospinal fluid leaks, if encountered, should be managed in the same surgical session. The transmastoid approach is helpful in repairing defects smaller than 1 cm in diameter, whereas the combined transmastoid-minicraniotomy approach provides good access when closing defects larger than 1 cm in diameter and also enables auto-calvarial grafting.