Even though intracranial hypertension is common after aSAH, only a limited number of studies have assessed the course of ICP and its effects on outcome.10-14 Heuer 10 described the relative frequency of this condition in aSAH; 54% had HICP, including a significant proportion (48.7%) with a good clinical grade compared with the 63.6% who were with a poor grade on admission. HICP was associated with poor outcome, particularly where it did not respond to treatment. In a small microdialysis study, HICP was associated with severely deranged cerebral metabolism, namely a pathological increase in lactate/pyruvate ratio and glutamate and glycerol, probably reflecting secondary brain injury.11 Recently, Zoerle 12 demonstrated that >80% of aSAH patients suffered at least one episode of HICP in the first week, with the highest mean ICP exceeding 20 mm Hg in 36%. The burden of HICP peaked 3 days after subarachnoid hemorrhage and declined after day Background and Purpose-Intracranial pressure (ICP) control is a therapeutic target in patients with aneurysmal subarachnoid hemorrhage, although only a limited number of studies assessed its course and effect on outcome. Pressuretime dose (PTD ICP ) is a method to quantify the burden and the time spent above a defined threshold of ICP. PTD ICP or its relationship with outcome has never been evaluated in aneurysmal subarachnoid hemorrhage. Methods-Analysis of data prospectively collected from aneurysmal subarachnoid hemorrhage patients admitted toNeurointensive Care Unit. Monitored data, including intraparenchymal ICP, were digitally recorded minute-by-minute in the first 7 days. PTD ICP (mm Hg h) was computed using 4 predefined thresholds (15,20, 25, and 30 mm Hg). Outcome was assessed through Extended Glasgow Outcome Scale at hospital discharge and at 6 months. Results-Fifty-five patients were enrolled. Forty-two patients (76%) presented with a poor clinical grade. Overall, mortality was 17% at hospital discharge and 34% at 6 months. Half of patients required extensive therapy to control high ICP during day 1. Median ICP was 10 mm Hg (4-75), whereas median PTD ICP15 , PTD ICP20 , PTD ICP25 , PTD ICP30 were, respectively, 13, 4, 2, and 1 mm Hg h. We observed an association between mortality at hospital discharge and higher level of PTD ICP using 20, 25, and 30 mm Hg as thresholds and between exposure to a moderate-level PTD ICP30 and unfavorable long-term outcome. Conclusions-PTD ICP may better define one of the insults that the brain suffers after aneurysmal rupture, and exposure to moderate PTD ICP30 was significant prognostic factor of 6-month unfavorable outcome.