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Ultrasound and Doppler phenomenon form the basis of the ultrasound diagnostics of blood vessels. They permit to visualize vessel walls and blood flow and to measure its velocity and direction. Thanks to these possibilities the new non-invasive techniques, faciliating the assessement of extra- and intracranial arteries and monitoring of collateral circulation in their severe lesions came into being. Extra- and intracranial blood flow in 405 patients was assessed by USG-D examination. It was impossible to conduct the examination of intracranial arteries in 40 patients, normal flow has been found; in 234 patients, in 30 patients disorders of vertebral-basal circulation were found, in 29 patients they were caused by lesions of intracranial arteries, and in 37 patients by lesions only in extracranial arteries. In 35 patients severe and disseminated vascular lesions were found the above observation was based on the assesement of both extra- and intracranial blood flow. The assessement also faciliated monitoring of collateral circulation.

Transcranial Doppler (TCD) studies are very useful for the evaluation of intracranial pressure changes. The most informative for the TCD increase diagnosis are the diastolic pressure decrease and increase of two computed indices: pulsatility index (PI) and resistance index (RI). Single measurements can be misleading and therefore, monitoring of neurosurgical intensive care patients is suggested. Additional information is provided by TCD studies in cerebral blood flow autoregulation tests. The usefulness of TCD in brain death diagnosis is discussed also.