[The potential usefulness of transcranial Doppler sonography in cerebrovascular surgery].

In 30 patients undergoing neurosurgical intervention, the authors evaluated the hemodynamics in the circle of Willis by transcranial Doppler sonography. By avoiding confusion with collateral effects, the transcranial Doppler sonography yielded direct and more significant information concerning the intracranial hemodynamics than extracranial Doppler sonography. Therefore, it made possible to detect intracranial occlusive lesions with less false findings. It gave us more accurate information on the effectiveness of reconstructive vascular surgery. In two of five consecutive patients with a proven aneurysmal subarachnoid hemorrhage, sound-spectrogram specific to stenosis was detected from the basal cerebral arteries which accompanied increase of the time-mean velocity of the upper spectrum and decrease of S/D ratio. Transcranial Doppler sonography was considered to contribute to the establishment of a protocol for early diagnosis and treatment of vasospasm. Transcranial Doppler sonography was also utilized as a useful tool for classification of arteriovenous malformation from the viewpoint of hemodynamics, namely high-flow or low-flow and with or without steal phenomenon. Transcranial Doppler sonography appears sufficiently promising to justify further development and utilization in cerebrovascular surgery.