Effects of CSF and perilymphatic pressure on cochlear function

Abstract

Alternation of the perilymphatic pressure and cochlear microphonics were investigated by increasing CSF pressure (0-100 cm H₂O) in guinea pigs.
Perilymphatic pressure increased in a linear manner without any time lag as the CSF was pressurized.
Cochlear microphonics was suppressed as the CSF was pressurized to more than 30 cm H₂O, and CM suppression was greater at low frequency sounds. Endolymphatic dc potential indicated no change until the CSF pressure was increased up to 70 cm H₂O. These results indicate that CM suppression with increased CSF pressure is due to the increased basilar membrane stiffness.