Endolymphatic hydrops in perilymphatic fistula.

Cochlear hydrops was produced either by injecting artificial perilymph into the subarachnoid space or by sucking perilymph through the round window membrane. The animals were either vitally fixed immediately or kept alive for 1 to 3 months before fixation. Conventional celloidin embedding method was used for serial sectioning. Animals with cochlear hydrops were selected from among 56 guinea pigs; 13 animals were used for the present observation. The cochleas of these animals showed slight to moderate hydrops, while the vestibule and semicircular canals demonstrated either a normal or collapsed endolymphatic space. The pars superior does not develop hydrops. Changes in the saccular wall were not pronounced. One animal developed marked cochlear hydrops with atrophy of both Corti's organ and stria vascularis. The vestibule and semicircular canals showed marked collapse. The ductus reuniens and the saccule were completely obstructed. Marked cochlear hydrops was produced by blocking the longitudinal flow of endolymph. It is assumed that there may be cochlear hydrops in clinical cases of perilymphatic fistula, with various pathologies of the endolymphatic space of the vestibule and semicircular canals.