The Authors report their preliminary experiences concerning the use of transcranial Doppler (TCD) in the pre- and postoperative monitoring of extracranial carotid surgery. TCD is a non invasive method of investigation able to give informations about the distribution of cerebral blood flow and about the mechanisms of compensation of Willis' circle. Furthermore, TCD showed itself to be very useful in the postoperative qualitative evaluation of surgery, pointing out, as a general rule, an increased flow in the middle cerebral artery after thromboendarterectomy of internal carotid artery. This haemodynamic modification, if present, is perceptible since the immediate postoperative period and becomes more evident and definitely stable at a distance of 20-30 days after operation, likewise the definitive stabilization of Willis' circle's haemodynamics.
