Intra-operative measurement of cortical arterial flow volumes in posterior circulation using Doppler sonography.

Little has been reported on the flow volume of cortical arteries in the posterior circulation. During craniotomy in 28 patients, we measured the flow velocity of the arteries using microvascular Doppler sonography and recorded their arterial radii and the insonation angle. The flow velocities and radii were 25.7 cm sec-1 and 0.11 cm for the posterior cerebral artery (PCA), 19.5 cm sec-1 and 0.07 cm for the superior cerebellar artery (SCA), 19.6 cm sec-1 and 0.04 cm for the anterior inferior cerebellar artery (AICA), 14.9 cm sec-1 and 0.05 cm for the posterior inferior cerebellar artery (PICA), 28.3 cm sec-1 and 0.18 cm for the basilar artery, and 18.5 cm sec-1 and 0.16 cm for the vertebral artery, respectively. Since the flow velocities of these arteries were confined in a narrow range compared to the cross-sectional areas, the latter was considered to be the primary determinant for flow volume in these arteries. Based on certain assumptions, we estimated the flow volume of the PCA, SCA, AICA and ICA to be 60, 20, 10 and 10 ml min-1, respectively, which could be regarded as the current reference values for the arterial flow volumes.