Effects of increased cerebrospinal fluid pressure on cochlear and cerebral blood flow.

We investigated the effects of increased cerebrospinal fluid (CSF) pressure on cochlear blood flow (CoBF) and cerebral blood flow (CBF) in guinea pigs. CoBF and CBF were recorded simultaneously using two laser-Doppler flowmeters, and blood flow volume in each part of the cochlea and the brain was measured by the non-radioactive microsphere method. CoBF was reduced by increased CSF pressure but the reduction was not persistent. Although inner ear pressure was elevated to the same level as CSF pressure, CoBF was not decreased by the pressure elevation as much as was CBF. Our results suggest that CoBF is relatively resistant to increases in CSF pressure.