Transcranial Doppler studies in aneurysm patients.

Fifty patients with ruptured intracranial aneurysms and 8 patients with elective clipping of unruptured aneurysms had daily transcranial Doppler (TCD) measurements performed. The highest mean middle cerebral artery velocity (MCA-Vel) was considered to be the best single parameter for judging a patient's susceptibility to clinically significant vasospasm (VSP). Surgery for the clipping of unruptured aneurysms by itself does not lead to an increase in MCA-Vel. There is a progressive increase in MCA-Vel after subarachnoid hemorrhage (SAH) from aneurysms which peaks between 7 and 10 days. The MCA-Vel is higher on the side of the ruptured aneurysm and the degree of rise is greater if blood is seen on the initial CT scan. It is highly unlikely that a patient whose MCA-Vel remains under 100 cm/sec has a degree of angiographic VSP which causes clinical symptomatology. Patients whose MCA-Vel is greater than 200 cm/sec are at great risk of developing clinical symptomatology of VSP and are very likely to have significant angiographic VSP. There is a transitional zone in between these two levels.