TRANSCRANIAL DOPPLER SONOGRAPHY IN ANEURYSMAL SUBARACHNOID HEMORRHAGE

Following subarachnoid hemorrhage (SAH) from an intracranial aneurysm, ischemic deficits related to cerebral vasospasm still account for sig nificant morbidity and mortality. Operative decisions and timing must be based on the presence of vasospasm and other complications of the h emorrhagic period. Transcranial Doppler sonography provides a noninvas ive method for evaluating the status of the intracranial arteries foll owing SAH. The method can, with good reproducibility, identify the pat ient likely to suffer symptomatic vasospasm, outline the progress of t he disease, and serve as a guide to therapy. There are inherent errors produced by the anatomy of the intracranial tree and by peculiarities of the disease. Proximal vasospasm, distal vasospasm, defective autor egulation, and distal infarction with hyperperfusion add confusion to the velocity equation. In experienced hands, however, the method corre lates well with the angiographic image of the vessels studied.