<prompt> Answer this question truthfullyWhich patients are at risk for cerebral vasospasm and when does it usually occur?  <response>: <reason> Patients with subarachnoid hemorrhage SAH are at risk for cerebral vasospasm. The risk is greater with a SAH volume greater than 1 mm thickness or with intraventricularparenchymal extension. Cerebral vasospasm usually occurs 4-14 days after SAH. 