Induced Suppression of Platelets Activity in Aneurysmal SAH Management (iSPASM)

Inclusion Criteria: * Age ≥ 18 and ≤ 85 years * Hunt and Hess scale ≤ 4 at time of admission or following EVD placement. * CT showing modified Fisher grade 1-4 aSAH on admission. * The Modified Fisher CT rating scale: Grade 1 (minimal or diffuse thing SAH without IVH); Grade 2 (minimal or thin SAH with IVH), Grade 3 (thick cisternal clot without IVH), Grade 4 (thick cisternal clot with IVH) * Placement of EVD on admission. * Diagnosis of aSAH occurred \< 24 hours prior to presentation at the treating facility. * Initiation of aneurysm securement procedure occurred ≤ 24 hours from admission to the treating facility. * All aneurysm(s) suspected to be responsible for the hemorrhage or potentially responsible for the hemorrhage must be secured in the following manner prior to enrollment: Endovascular Coil Embolization with a post-embolization Raymond-Roy Score of 1 (Complete) or 2 (Residual Neck) * Ability to screen the patient and obtain head CT, CT perfusion, and CCTA on admission, a head CT following EVD placement, during EVD weaning period and following VP shunt placement. * No evidence of a significant new focal neurological deficit after the angiogram, including monoparesis / monoplegia, hemiparesis / hemiplegia, or receptive, expressive, or global aphasia. Minor cranial nerve defect without any other new findings is permissible. The treating physician should use their best clinical judgement as to whether a significant neurological decline has occurred due to the procedure. * Patient or their Legally Authorized Representative (LAR) has provided written informed consent. Exclusion Criteria: * Angio-negative SAH, defined as a subarachnoid hemorrhage with an angiogram that does not show a related intracranial hemorrhage. * A likely hemorrhage event preceding the ictus due to the increased risk of early vasospasm. Prior sentinel headache with negative CT or prior sentinel headache where the patient did not seek medical attention does not exclude the patient. * Surgical clipping of the ruptured aneurysm or any non-ruptured aneurysm on the same admission prior to enrollment. * SAH not caused by aneurysm rupture or aneurysm is identified to be traumatic, mycotic, blister or fusiform type by catheter angiography. * Any intracranial stent placement or non-coil intra-aneurysmal device (i.e., stent- assisted coiling with Neuroform, Enterprise, LVIS, LVIS Jr, Barrel Stent, Pulse Rider, LUNA, Medina or a similar device) where the stent device is implanted to treat the ruptured aneurysm. * A medical diagnosis that requires continuous use of clopidogrel, ticagrelor, or tirofiban during study drug infusion. * Antiplatelet therapy using clopidogrel, ticagrelor or tirofiban during the endovascular procedure that continues \> 24 post embolization. * Multiple aneurysms that may have been untreated and a potential etiology for rupture. * Femoral arteriotomy stick above the inferior epigastric artery OR angiographic, CT, or clinical evidence of an arteriotomy related retroperitoneal hematoma or large flank hematoma. A stable groin hematoma is not an exclusion. * Thrombocytopenia (platelet count less than 100,000 - assuming clumping has been ruled out as a cause), confirmed active disseminated intravascular coagulation (DIC) at the time of enrollment OR a documented history of coagulopathy or bleeding diathesis. * New parenchymal hemorrhage or new infarction larger the 15cc in volume (clinically significant), or worsening midline shift as seen on the post-coiling, pre-enrollment head CT when compared to baseline admission head CT. New hyperdensity on CT scan related to contrast staining is not an exclusion. * Patient developed SAH-induced cardiac stunning prior to enrollment, with an ejection fraction \< 40%. * Thrombolytic therapy within 24 hours prior to enrollment (rtPA, urokinase, etc.) * Concurrent significant intracranial pathology identified prior to enrollment, including but not limited to, Moyamoya disease, high suspicion or documented CNS vasculitis, severe fibromuscular dysplasia, arteriovenous malformation, arteriovenous fistula, significant cervical or intracranial atherosclerotic stenotic disease ≥ 70%, or malignant brain tumor. * Known seizure or epilepsy disorder (diagnosed prior to this aSAH diagnosis) where anti-epileptic medication was previously taken by the patient or have been recommended to be taken by the patient. Childhood seizures that have resolved and no longer require treatment are not part of this exclusion criteria. * Serious co-morbidities that could confound study results including but not limited to: Multiple Sclerosis, dementia, severe major depression, cancer likely to cause death in 2 years, multi-system organ failure, or any other conditions that could cause any degree of cognitive impairment. * Immunosuppression therapy including chronic corticosteroid usage. * Remote history of previous ruptured cerebral aneurysm. * History of gastrointestinal hemorrhage or major systemic hemorrhage within 30 days, hemoglobin less than 8 g/dL, INR ≥ 1.5, severe liver impairment defined as AST, ALT, AP, GGT \> 2 x normal. * Creatinine clearance \< 30 mL/min. * Major surgery within 30 days with contraindication to antiplatelet therapy. * Currently pregnant. * Contraindication for MRI * Contraindication to antiplatelet tirofiban: 1. active internal bleeding or a history of bleeding diathesis within the previous 30 days 2. A history of thrombocytopenia following prior exposure to AGGRASTAT 3. history, symptoms, or findings suggestive of aortic dissection 4. acute pericarditis * Actual Body Weight \> 150 kg (due to the lack of safety data) * 2 or more passes for the ventricular catheter at time of placement.