Effects of Perilymph Volume Adjustments on Cochlear Blood Flow in the Guinea Pig

Abstract

Previous research suggests a potential relationship between perilymphatic pressure (Pp) and cochlear blood flow (CBF); however, the alterations in Pp necessary to produce changes in CBF have not been adequately described or quantified. The effects of perilymph volume changes on systemic blood pressure (BP) and CBF were presently investigated in the guinea pig cochlea. Five μl of perilymph were displaced in each of three conditions: viz. evacuation of 5 μl from the cochlea; replacement of these 5 μl; and finally the addition of 5 μl of artificial perilymph into the cochlea. AH perilymph volume adjustments were completed in 1-ul increments during which changes in CBF and BP were recorded. Significant alterations in CBF were observed during 1-ul perilymph volume adjustments in each condition with no significant changes in systemic BP. The results from this study support our hypothesis that an inverse relationship exists between CBF and Pp in that decreases in perilymph volume yielded elevations in CBF while increases in perilymph volume yielded reductions in CBF.

Key Words:

• perilymphatic pressure
• blood pressure
• laser Doppler flowmeter