© American Roentgen Ray Society Effect of Head Turning on Blood Flow in Lateral

The pattern of blood flow leaving the cranium via the lateral sinuses and internal jugular veins is significantly altered by head rotation. This effect is documented in the baboon and macaque monkey by Doppler flow recording and by angiography. This phenomenon may affect the validity of cerebral blood flow data determined by venous sampling and may have significance in angiographic interpretation and in the clinical course of patients with a hypoplastic or occluded lateral sinus or internal jugular vein. It has been generally assumed that a rel atively fi xed proportion of the total cerebral blood effluent leaves the cranium via the right and left lateral sinuses. However, using a monkey to study the effects of a variety of factors on cerebral blood flow, one of us (L. G. D.) incidentally noted a shifting pattern from one lateral sinus to the other one with head turning. Using c hronically implanted Doppler flow meters on the lateral sinuses and angiography, we tried to determine the effect of head turning on flow in the lateral sinuses in several nonhuman primate specimens. Our findings are reported, and some potentially important diagnostic and therapeutic implications are discussed briefly