CORRELATION OF REGIONAL CEREBRAL BLOOD-FLOW AND BLOOD-FLOW VELOCITY IN NORMAL VOLUNTEERS AND PATIENTS WITH CEREBROVASCULAR-DISEASE

Transcranial Doppler sonography and measurement of regional cerebral blood flow using the Xenon-133-inhalation technique have been used simultaneously in 10 normal volunteers and 13 patients with acute-onset cerebrovascular disorders during normocapnia and during hyperventilatory hypocapnia. Hypocapnia led to a reduction of both blood flow and blood velocity in the territory of the middle cerebral artery. However, correlation was poor in most cases with respect: 1) to hemispheric blood flow and flow velocity over the middle cerebral artery (BFV), 2) cerebral blood flow (CBF) over the middle cerebral artery (MCA) and BFV and 3) percentage changes of CBF over the MCA and BFV during hypocapnia. In normals correlation usually was better than in patients with cerebrovascular disorders. It was concluded that measurement of BFV over the MCA using transcranial Doppler sonography does not reflect either cerebral tissue perfusion or changes of tissue perfusion induced by alteration of CO2-content in the arterial blood.