Intraoperative evaluation of cerebral hemodynamics using directional Doppler technique. Part 1: Arteriovenous malformations.

The use of a pulsed echo Doppler technique during surgery for cerebral arteriovenous malformation is described. The equipment and the methods employed are presented. The main advantages are easy determination of flow direction and pattern of the vasculature involved, allowing a precise discrimination between inflow and outflow channels. Deep-seated malformations, not visible at the brain surface, can be located with the Doppler technique. The ultrasound probe was placed on the brain surface with a slight pressure on the intact pia mater. The precise direction and depth of the malformation could be determined in relation to the recording site. This facilitated the planning of cortical incisions, identification of vessels involved, and the vascular procedure to be employed.