Middle meningeal artery (MMA) embolization via a minimally invasive endovascular approach has been attempted with the goal of eliminating the arterial supply to the vascularized membrane. The investigators have recently presented the first known case series of MMA embolization as upfront treatment for cSDH in lieu of surgical evacuation (publication pending). Five patients underwent successful embolization of the MMA with subsequent reduction in size or complete resolution of cSDH with no peri-procedural complications.

The purpose of this study will be to evaluate the safety and efficacy of MMA embolization compared to traditional surgical management for symptomatic, chronic, and medically refractory SDH. MMA embolization is an established procedure used routinely for treatment of tumors or vascular malformations; this study investigates the use of an established procedure for a new disease. The investigators hypothesize that MMA embolization will afford a particularly fragile patient population an alternative to invasive and morbid neurosurgical intervention.

The purpose of this study will be to evaluate the safety and efficacy of middle meningeal artery (MMA) embolization compared to traditional surgical management for symptomatic, chronic, and medically refractory subdural hematoma (SDH). MMA embolization is an established procedure used routinely for treatment of tumors or vascular malformations; this study investigates the use of an established procedure for a new disease. The investigators hypothesize that MMA embolization will afford a particularly fragile patient population an alternative to invasive and morbid neurosurgical intervention.

Since subjects being enrolled will be those that are symptomatic from chronic SDH, pre-procedural data such as clinical history, neurologic examination, and CT scans will already be available. The day after the embolization, subjects will undergo a clinical interview to assess change in symptoms. A neurologic exam and CT scan will also be performed prior to discharge. Telephone surveys will be used at intermittent time points to assess for change in clinical symptoms. The subjects will also present in clinic for a follow up clinical interview, neurologic exam, and CT scan at 2 and 6 weeks post-procedure. This follow up care including the CT scans is considered standard of care for patients undergoing surgery for chronic SDH and it will not expose them to any additional tests or imaging studies.

MMA embolization is done under moderate sedation or general anesthesia using biplane fluoroscopy. Briefly, common femoral artery access is obtained, and a guide catheter is advanced into the external carotid artery. A microcatheter is then advanced into the internal maxillary artery and then the MMA. Particles are then injected. A post-procedure carotid angiography is performed to ensure no reflux of particles into the internal carotid artery circulation. The guide catheter is then removed and femoral hemostasis is obtained. Subjects recover from anesthesia and are observed overnight, undergo a non-contrast head CT the next day, and discharged if appropriate.

Inclusion Criteria:

• Age must be greater or equal to 18 years of age.
• Subjects must have a diagnosis of chronic or acute-on-chronic subdural hematoma based on brain imaging, as documented by an independent radiologist.
• One or more symptoms attributable to chronic SDH including headache, cognitive impairment, gait instability, seizure, or mild focal neurologic deficit.
• In the opinion of the site investigator or the subject's referring physician, the subject has failed conservative management.

Exclusion Criteria:

• The subdural hematoma is causing mass effect significant enough to cause marked or progressive neurologic impairment.
• Any requirement for urgent surgical evacuation is necessary.
• Life expectancy is less than 6 months in the opinion of the subject's primary physician.
• Markedly tortuous vasculature precluding safe endovascular access, as assessed on angiogram.
• Acute subdural hematomas.
• Pregnancy

De-identified participant data for primary and secondary outcome measures will be available.

Data will be available within one year of study completion

Data access requests will be reviewed by the PI.