When estimating intracranial pressure (ICP) using TCDs, the available formulas tend to over­estimate it due to autoregulatory effects and compartmentalization of pressures and its differ­ential effect along the vessel length. Most predic­tive models for noninvasive ICP measurements are based on initial studies in traumatic brain injury and assume normal caliber of vessels; hence their applicability in focal compartmen­talized intracranial pathologies like ischemic or hemorrhagic stroke or in pathologies involving vasospasm, as in subarachnoid hemorrhage, is unclear [1]. Accuracy and normative values for cerebral autoregulation testing using TCDs have been validated only for middle cerebral arter­ies. The use of mean ow velocities on TCD to predict vasospasm has high sensitivity but low specicity with dissociation between occurrence of sonographic vasospasm and delayed cerebral ischemia. Despite these limitations, TCD contin­ues to be the only diagnostic modality available for routine noninvasive screening of patients at risk [13].