[Changes in blood flow velocity in the basal cerebral arteries following neck dissection]

Cerebral blood-flow velocities (cm/s) and pulse index (PI) were studied pre- and postoperatively in a total of 15 male patients following bilateral radical/functional (group A; n = 10) or unilateral radical neck dissection (group B; n = 5) using a 2 MHz-pulsed transcranial Doppler ultrasonographical system (TCD), with a transtemporal approach to the middle cerebral artery. Systolic and mean flow velocities were significant reduced with subsequent increases in PI during the first postoperative sonography in group A-patients while no significant differences in TCD date developed in group B. Blood-flow velocities and PI reached control values within three days. General hemodynamic and respiratory parameters did not influence the changes in TCD flow profiles with the exception of moderate increases in arterial CO2 during the early postoperative period. It is concluded that the reductions in blood-flow velocities and concomitant increases in PI reflect a heightened resistance to flow in the arterial cerebral vasculature. The decrease in cerebral vascular compliance suggests increases in the cerebral venous outflow following the resection of essential drainage pathways. However, TCD does not provide any information about the adequacy of cerebral blood flow.