Fluorescein use in the detection of perilymphatic fistula: a study in cats.

A stained or colored perilymph would be a valuable tool to otologists for the detection of a perilymph fistula. We studied the effect of intravenously injected fluorescein on the inner ear in seven cats. Still and video photography was used to clearly document our findings. Intravenously injected fluorescein appeared within the soft tissue in less than 1 minute and stayed there for at least 3 1/2 hours. Fluorescence around the round window niche resulted from soft tissue (mucosal) fluorescence and extravasation of interstitial fluid (transudate). No fluorescence of perilymph was detected. Because of this, we do not believe intravenously injected fluorescein is useful in the detection of perilymph fistula. Intrathecal injection caused quick and intense staining of labyrinthine fluid.