Measuring the cochlear blood flow using a laser Doppler flowmeter

Abstract

Using laser-Doppler flowmeter, the cochlear blood flow (CoBF) in response to an interruption of the internal auditory artery (IAA) was observed in guinea pigs. In order to interrupt the IAA, the bundle of vessels and nerves in the internal auditory canal was compressed and dissected. After compression, CoBF decreased to 30%-50% of the original value with a wide individual variation. The CoBF reading even after the dissection of the IAA did not reach zero and showed the same value of compression in the same animal. The residual CoBF after the dissection of the IAA was not influenced by the dynamic change in the systemic blood pressure, and thus no other blood supply to the cochlea was considered. The residual CoBF may thus be derived from the persistent venous flow through the cochlear aqueduct. Based on the above results, we concluded that to correctly estimate the decreasing degree of the CoBF during the compression of IAA, the calibration excluding the residual CoBF after the dissection of the IAA is neces- sary.