Neuroepithelial Cysts of the Middle Ear

Abstract

Neuroepithelial cysts are lesions of the central nervous system that have previously been reported in cerebral parenchyma, in the spinal cord, and within the ventricles in association with the choroid plexus. We describe 2 cases of neuroepithelial cysts of the middle ear. One was diagnosed after surgery for a retraction pocket and chronic otitis media complicated by an intraoperative cerebrospinal fluid (CSF) leak. The other produced bilateral spontaneous CSF otorrhea and mimicked the presentation of arachnoid granulations. Both cases were verified with immunohistochemical stains. Neuroepithelial cysts, although rare, should be considered in the differential diagnosis of spontaneous CSF otorrhea or an epitympanic mass.

Arachnoid Granulations of the Temporal Bone

“…Other causes for communication between temporal bone and intracranial compartments were not evident in this study. Labyrinthine anomalies, for example, were not encountered, and no heterotopic neuroepithelial cysts were found in young or old subjects (17).The link between enlarging AGs and the development of spontaneous CSF effusions and meningitis is strengthened by Gacek's (8) observations that 6 of 9 older subjects with large bony defects (92 mm 3 ) had a history of middle ear effusions or meningitis, whereas all subjects with bony defects smaller than 1 mm 3 were asymptomatic.…”