Puerto Rico Embolization of the Middle Meningeal Artery (PREMMA) trial is a multi-center, parallel, prospective, superiority, randomized controlled trial with concealed allocation comparing reoperation rates and neurological outcomes in patients with chronic subdural hematoma that receive treatment via embolization of the middle meningeal artery versus surgical evacuation via burr hole trephination or craniotomy.

Chronic subdural hematoma (cSDH) is a collection of fluid and blood breakdown products that evolves over weeks to months in the subdural space. This condition is more common among people older than 65 years and has been associated with increased use of antithrombotic therapy among this population. The World population is rapidly aging; thus, the investigators expect the number of patients with cSDH will increase. The United Nations World Social Report places Puerto Rico in the 7th place of countries with the largest share of people aged 65 years or over. This pathology burdens healthcare systems; therefore, assessing the feasibility of treatment modalities for cSDH that are less invasive, have lower procedural risks, and have lower recurrence rates that require additional surgical intervention is essential.

The standard of care for symptomatic cSDH is the surgical evacuation (SE) of the hematoma, with recurrence rates between 10-30% and surgical rescue indicated for most of these cases. Evacuation of the hematoma effectively relieves its mass effect but does not change the underlying pathophysiologic mechanism. In recent years, embolization of the middle meningeal artery (eMMA) has been shown to decrease the recurrence of chronic subdural hematoma and the need for revision burr hole or craniotomy. The PREMMA trial aims to compare embolization of the middle meningeal artery as stand-alone treatment for chronic subdural hematoma versus the standard of care, surgical evacuation.

Inclusion Criteria:

• Age ≥ 21
• Speak and understand Spanish or English
• Resident of Puerto Rico
• Glasgow coma scale ≥ 14/15
• Presence of cSDH on non-contrast computed tomography (NCCT) or magnetic resonance imaging (MRI)
• Neurological indication for treatment of cSDH (Markwalder scale ≤ 2)
• No previous surgical or endovascular treatment for symptomatic cSDH
• Signed informed consent for participation in the study by the patient or legally authorized representative

Exclusion Criteria:

• Acute subdural hematoma
• Focal, non-hemispheric localization of cSDH
• Evidence of other lesions associated with cSDH, such as neoplasms, vascular lesions, or additional epidural, subarachnoid, or parenchymal hemorrhage on non-contrast computed tomography or magnetic resonance imaging
• Imaging evidence of skull fracture over the subdural hematoma
• Presence of any cerebrospinal fluid (CSF) shunt
• Imaging evidence of midline shift ≥ 10 mm
• Imaging evidence of basal cistern effacement
• Imaging evidence of dilatation of lateral ventricles
• Imaging evidence of uncal herniation
• Modified Rankin scale ≥ 3 before developing symptoms associated with cSDH
• Contraindications for angiography (i.e., complex anatomy or kidney failure)
• Comorbidity making follow-up impossible
• Pregnancy
• Vulnerable patients, including homeless patients, incarcerated patients, and mentally ill patients without appropriate medical decision-making proxies that the physician believes are incapable of appropriately assessing the risks of the procedure
• Absence of medical insurance