Inclusion Criteria- Patients >18 years of age
- Signs and symptoms suggestive of AIS or TIA
- One of the following:
1. BASE - Arrival to the emergency department or hospital within 18 hrs of symptom onset or last known normal time
2. BASE 24 - Arrival to the emergency department or hospital within 24 hours +/- 6 hours (i.e. 18 - 30 hour window) of symptom onset or last known normal time and clinical evidence suggesting Acute Ischemic Stroke.
- Head CT or MRI ruling out other pathology such as vascular malformation, hemorrhage, tumor or abscess which would likely be responsible for presenting neurologic symptoms
- Informed consent obtained
Exclusion Criteria- Any central nervous system infection, i.e. meningitis or encephalitis in the past 30 days
- Any form of head trauma, stroke or intracranial hemorrhage in the past 30 days
- Known primary or metastatic cancer involving the brain
- Active Cancer defined as a diagnosis of cancer, within 6 months before enrollment, any treatment for cancer within the previous 6 months, or recurrent or metastatic cancer.
- Autoimmune diseases: such as lupus, rheumatoid arthritis, Crohn's disease, ulcerative colitis
- Active infectious diseases (eg. HIV/AIDS, hepatitis C)
- Any underlying medical condition which in the opinion of the investigator would prohibit the patient from providing informed consent
- Major surgery within three months prior to the index event