Relationships of labyrinthine fluid pressures and blood flow.

Control of labyrinthine blood flow analogous to the autoregulation of cerebral blood flow has been suggested but not experimentally demonstrated. This study concerns the influence of systemic arterial pressure changes on the perilymph and CSF pressures in cats with the cochlear aqueduct (CA) blocked. No direct correlation was found between changes in arterial and CSF pressure. This seemed to be due to the efficient autoregulation of the global cerebral blood flow--a main factor for CSF pressure regulation. The CSF and central venous pressures induced little and much delayed influence on the perilymph pressure when the CA was blocked. However, there was a direct correlation between changes in systemic arterial pressure and the perilymph pressure. This relationship seemed to be mediated via changes in local labyrinthine blood flow. The study indicated a lack of autoregulation of labyrinthine blood flow and a direct correlation between labyrinthine fluid pressure and blood flow when the CA was obstructed.