Prophylactic hypervolemia or balloon angioplasty before the development of angiographic spasm is not recommended (Class III; Level of Evidence B). (New recommendation) 4. Transcranial Doppler is reasonable to monitor for the development of arterial vasospasm (Class IIa; Level of Evidence B). (New recommendation) 5. Perfusion imaging with CT or magnetic resonance can be useful to identify regions of potential brain ischemia (Class IIa; Level of Evidence B). (New recommendation) 6. Induction of hypertension is recommended for pa- tients with DCI unless blood pressure is elevated at baseline or cardiac status precludes it (Class I; Level of Evidence B). (Revised recommendation from previ- ous guidelines) 7. Cerebral angioplasty and/or selective intra-arterial vasodilator therapy is reasonable in patients with symptomatic cerebral vasospasm, particularly those who are not rapidly responding to hypertensive therapy (Class IIa; Level of Evidence B). (Revised recommendation from previous guidelines) Management of Hydrocephalus Associated With aSAH Acute hydrocephalus occurs in 15% to 87% of patients with aSAH.234 240 Chronic shunt-dependent hydrocephalus, on the other hand, occurs in 8.9% to 48% of patients with aSAH.234 238,240 244 There is only 1 randomized, controlled trial pertaining to the management of hydrocephalus associ- ated with aSAH245 and 2 meta-analyses236,243; the rest of the literature consists of nonrandomized case-control, case series, or case reports. Acute hydrocephalus associated with aSAH is usually managed by external ventricular drainage (EVD) or lumbar drainage. 