[Relationship between summating potentials and perilymphatic fistula].

Serial electrocochleogram (ECochG) recordings were obtained within 24 hours from 40 guinea pigs with experimentally induced PLF, and the cochlears of 30 guinea pigs (60 ears) were histopathologically observed under light microscope. -SP occurred in 100% experimented ears within 1-3 hours after PLF, but distention of Ressner's membrane was found only in 30% ones. CAP thresholds and N1 latencies of 10 animals were improved, accompanying disappearance of -SP in 6 of the 10 animals in 24 hours after PLF. It is presumed that -SP is not a specifically electrophysiologic indicator of ELH, and that the generation of -SP may chiefly result from reversible damage of cochlear hair cells. The mechanical factor of basilar membrane displacement can hardly be considered as a main cause of SP abnormality. The mechanism of the ELH following PLF was also discussed.