[Transcranial Doppler ultrasonography in head and neck tumors].

Transcranial Doppler ultrasound (TCD) recording is a non-invasive diagnostic procedure for the evaluation of the cerebral collateral flow in patients, in whom therapeutic ligation or resection of the common and/or internal carotid artery is planned. Patients are first examined under resting conditions, and then under manual compression of the ipsilateral carotid artery. Since January 1989, 31 ENT and neurosurgical patients have been examined. In all patients an immediate decrease in flow velocity in the middle cerebral artery (mca) of about 25% to 90% was recorded. In 42.8% of the patients the mca flow velocity reached 90% or more of its value under normal conditions within a short period. In 29% of the patients the mca flow velocity under manual compression of the carotid artery remained under 50% of its original value. In 68% of the cases TCD with manual compression of the carotid artery showed reliable results for the function of cerebral collateralisation as a prognostic factor of the risk of ischaemia due to haemodynamic changes after carotid ligation. In these cases no further examination of the cerebral collateral flow conditions was needed. The method is inexpensive, reproducible, and in comparison with cerebral angiography, convenient and non-hazardous for the patient.