Nitric Oxide Consumption as a Predictor of Vasospasm in Subarachnoid Hemorrhage

The goal of this observational study is to understand if angiographic cerebral vasospasm (CV) can be predicted by levels of nitric oxide (NO) consumption in patients with aneurysmal subarachnoid hemorrhage (SAH). To reach this goal, the investigators will compare NO consumption levels in SAH and non-SAH patients. NO consumption levels will be analyzed from samples of participants' cerebral spinal fluid (CSF).