Cerebrovascular Regulation in Preganglionic and Postganglionic Autonomic Insufficiency

Abstract

Cerebral blood flow was measured in four subjects with chronic idiopathic autonomic insufficiency using 85 Kr inhalation, cerebral A-V samples for scintillation counting, and O 2 content determination. Blood pressure was varied by up or down tilting and L-norepinephrine infusion. In three patients with typical Shy-Drager syndrome and preganglionic denervation, CBF regulation to pressure and Pa CO CO 2 change was intact. In a fourth patient with postganglionic denervation, CBF autoregulation was absent to changes in blood pressure but was preserved normally to increases or decreases in Pa CO CO 2 CBF and CMRO 2 , at rest were normal (52.6 cc and 3.1 cc). Hyperventilation to Pa CO CO 2 34.3 mm failed to restore autoregulation to increased blood pressure. The results imply a functional role for postganglionic autonomic fibers in CBF autoregulation.