Embolization of the Middle Meningeal Artery With ONYX™ Liquid Embolic System for Subacute and Chronic Subdural Hematoma

Open to people ages 18-90

• Pre-morbid Modified Rankin Score ≤3
• Confirmed diagnosis of subacute or chronic subdural hematoma
• Completed informed consent
• Meets criteria for Surgery or Observation Cohort

• Life expectancy <1 year
• Unable to complete follow-up
• Pregnant, lactating, or has a positive pregnancy test at time of admission
• Diagnosed with acute SDH
• Potentially dangerous anatomic variations leading to increased procedural risk or unsafe access for MMA embolization
• Pre-randomized Markwalder Grading Scale score ≥ 3
• Unmanaged, uncontrolled bleeding disorders/blood diathesis
• Presumed septic embolus, or suspicion of microbial superinfection
• Known active COVID-19 infection
• CT or MRI evidence of intra-cranial tumor or mass lesion Contraindication to angiography
• Participation in another clinical trial
• Contraindicated for the use of Onyx™ LES
• Cannot be taken off corticosteroids (intended to treat subacute or chronic SDH) for at least 90 days post-randomization