 Experimental evidence suggests that red blood cell hemolysis and subsequent release of oxygen, hemoglobin, reactive oxygen species, and other as yet undescribed mediators are necessary for the development of vasospasm. The goal of this study is to use modern tools of genomics to identify novel molecular markers for the process of vasospasm by studying the release of micro ribonucleic acids RNA that are secreted into the cerebrospinal fluid following the initiation of vasospastic cascades. Micro RNAs have recently been identified as important regulators of many cellular processes including cell cycle progression, proliferation, tumor suppressors, oncogenes, and regulators of metabolic pathways. The researchers propose to study the levels of annotated micro RNAs in the cerebrospinal fluid CSF of patients who present with subarachnoid hemorrhage from presentation through the hospital stay. The researchers will correlate the level of these micro RNAs with patient clinical presentation, including transcranial Doppler measurements, Glasgow Coma Scale score, vital signs, and angiographic studies. It is well established that the process of vasospasm occurs over the course of many days. Long before vasospasm becomes clinically evident, cellular processes causing spasm are in action and the researchers hope to identify micro RNA mediators of these processes using high throughput screening methods. 