Pre- and Postoperative Evaluation of Cerebral Blood Flow in Low-Pressure Hydrocephalus

Abstract

EVERAL theories have been launched to explain the often dramatic improvement that follows the shunting procedure in patients with hydrocephalus. In cases with intracranial hypertension an increase in blood flow seems a likely consequence of the reestablishment of normal pressure conditions. In low pressure hydrocephalus ~,1' the favorable results seem more difficult to explain. One theory, first set forth by Yakovlev, ~ states that the neurological disturbances, particularly those affecting the gait, are due to stretching of the long paracentral fibers located close to the walls of the lateral ventricles, and that release of this stretching could explain the postoperative improvements. Periventricular demyelination was found by Penfield and others, ~- and a vascular cause of the changes was considered most plausible. A decrease in cerebral blood flow has been found in occult hydrocephalus, in the high-pressure as well as in the low-pressure type, ~-~ and improvement of flow following the shunting procedure has been described in a few cases with an ectatic basilar artery. :,~ It therefore seems justified to present data allowing more definite and generalized conclusions to be reached about the pre- and postoperative cerebral circulation in hydrocephalic patients.