Significance of apparent intratympanic meningiomas.

Meningioma is the most common tumor of the central nervous system, but it has only been reported in 79 patients to involve the temporal bone. The 4 cases presented here show striking clinical similarity to a subgroup of 20 meningiomas reported to be entirely intratympanic; however, in each instance the extent, origin, and potential of the disease was not initially evident. Precise histopathologic diagnosis may be aided by electron microscopy. Current concepts of embryology lend credence to the possible role of arachnoid endothelial cells in the pathogenesis of intratympanic meningioma. An advanced intracranial meningioma may be overshadowed by the hearing loss, tinnitus, and otalgia calling attention to an intratympanic component. The clinician should remain suspicious of intracranial disease even after excision of an apparently well circumscribed intratemporal lesion. Progressive sensorineural hearing loss and persistent otalgia portend recurrent or intracranial disease. Follow-up for at least 10 years with judicious use of CT scans is suggested.