Study to Collect Real-world Performance and Safety Data on Penumbra System® in Population With Acute Ischemic Stroke (AIS).

Inclusion Criteria: * I.1. Patient age 18-75 years * I.2. Pre-stroke mRS 0-1 * I.3. Patients experiencing acute ischemic stroke who are eligible for mechanical thrombectomy using the Penumbra System * I.4. Frontline treatment with Penumbra System * I.5. Signed informed consent per Institution Review Board/Ethics Committee Exclusion Criteria: * E.1. Alberta Stroke Program Early CT Score (ASPECTS) ≤6 (for anterior circulation strokes) * E.2. Any comorbid disease or condition expected to compromise survival or ability to complete follow-up assessments through 90 days * E.3. Currently participating in an investigational (drug, device, etc.) clinical trial that will influence the endovascular procedure or acute treatment of the patient. Patients in secondary prevention, observational, natural history, and/or * epidemiological studies are eligible. * E.4. Other medical, behavioral, or psychological conditions that in the opinion of the Investigator could limit the patient's ability to participate in the study, including compliance with follow-up requirements, or that could impact the scientific integrity of the study