Perilymphatic Fistula

Perilymphatic fistula is a condition in which fluid leaks out from the inner ear and causes hearing loss and disequilibrium or vertigo.

Etiology for Perilymphatic Fistula

There are two types of fluid found within the inner ear: the perilymph and the endolymph.  Endolymph is found within the membranous portion of the inner ear. This membranous portion of the inner ear floats within perilymph.

Here you can see a panned out view of the cochlea.  In the next picture, you will see a zoomed in cross-section of the cochlea shown.

This shows a cross-section of the cochlea with the vestibular membrane, the membrane that separates endolymph and perilymph, in its proper position.

When the middle ear system is exposed to extreme changes in pressure such as when scuba diving, flying in an airplane, having an upper respiratory infection, or being slapped, inner ear trauma can occur to the point where perilymph can leak out of the inner ear into the middle ear. An area of the inner ear known as the round window is a common site of leakage.

A rupture of the round window membrane, the opening to the inner ear, causes a leakage of perilymph.