Flow and Pressure Changes in the Circle of Willis: Model Studies
The relative inaccessibility of the circle of Willis in the living animal has made it necessary to attempt to study pressure and flow conditions by means of a model. So far, a steady-flow, rigid model has been used which has evolved through a fluid model, an electrical analog, and a computer model (Arch. Neurol. 13:173–182, 1965, and Arch. Neurol. 13:164–172, 1965). Comparison of the model and the living animal (dog) has been made under conditions of middle-cerebral-artery occlusion, common-carotid occlusion, and vertebral-artery occlusion. In general, conformity of the two systems is good when only one afferent artery is occluded. Greater reduction of flow to the circle results in wider differences in model and prototype responses. Configuration studies were conducted to compare the configurations of the circle in dogs with that in man and monkeys.