Endolymphatic hydrops after fenestration: a temporal bone study with implications on the function of the utriculo-endolymphatic valve.

A temporal bone specimen demonstrating endolymphatic hydrops 13 years after fenestration of the lateral semicircular canal is presented. Fibro-osseous tissue extending from the lateral semicircular canal and reaching the vestibule produced fixation of the membranous wall of the utricle to the bony wall. Fixation and retraction of the utricule appears to have resulted in a permanently open utriculo-endolymphatic valve leaflet. Similar findings of fibro-osseous changes arising from the area of the crus commune and an open valve were found in a Meniere's disease specimen. The implications of these findings on the function of the valve are discussed.