THUNDER: Acute Ischemic Stroke Study With the Penumbra System® Including Thunderbolt™ Aspiration Tubing

Inclusion Criteria: 1. Patient age 18 - 80 years 2. Treatment within 8 hours of symptom onset 3. Pre-stroke mRS 0-2 4. Patient experiencing acute ischemic stroke secondary to intracranial large vessel occlusion in the internal carotid, middle cerebral (M1 or M2), basilar, or vertebral artery 5. If patient is eligible for thrombolytic therapy, it was administered as soon as possible, and no later than 3 hours from stroke symptom onset 6. Planned frontline treatment with Penumbra System including Thunderbolt modulated aspiration 7. Informed consent obtained per Institution Review Board/Ethics Committee requirements Exclusion Criteria: 1. Stenosis, excessive tortuosity, or any occlusion in a proximal vessel requiring treatment or preventing access to the thrombus 2. Alberta Stroke Program Early CT Score (ASPECTS) ≤6 or core infarct volume \>50 mL on MRI or CT-based imaging (for anterior circulation strokes) 3. Pregnant patient 4. Life expectancy \< 90 days due to comorbidities 5. Current participation in an interventional drug or device study that may confound the results of this study. Studies requiring extended follow-up for products that were investigational but have since become commercially available are not considered investigational studies 6. 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