PHIL™ Middle Meningeal Artery Embolization for First-Line Treatment of Chronic Subdural Hematoma IDE Trial

Inclusion Criteria: * Age 22 years or older * Diagnosis of chronic subdural hematoma * Subject, or their legally authorized representative provides a signed and dated Informed Consent Form * Pre-morbid mRS 0-1 * cSDH measures ≥ 10 mm in greatest thickness * cSDH exerts mass effect upon the subjacent brain * Imaging characteristics indicative of chronicity * Negative urine pregnancy test for female subjects of child-bearing potential * Subject is able and willing to comply with all study protocol requirements, including return to the investigational site for all follow-up visits * Subject presents with one or more of the following neurological symptoms: headache/head pressure, cognitive decline, speech difficulty or aphasia, gait impairment or imbalance, focal neurological deficit (weakness, paresthesia or sensory deficit involving of one or more extremities or facial droop), and/or seizure Exclusion Criteria: * Prior ipsilateral craniotomy or burr hole evacuation of cSDH * Prior embolization of either MMA * Requires (in the opinion of the treating surgeon) full or mini-craniotomy at time of randomization * Emergent subdural hematoma evacuation needed * cSDH with a focal location * cSDH developed due to underlying condition * Life expectancy of \<1 year * Presents with an intracranial mass other than subdural hematoma * Presents with a meningioma with mass effect and/or ≥1 cm or currently undergoing radiation therapy for carcinoma or sarcoma of the head or neck region * Serum creatinine level \> 3.0 mg/dL at time of enrollment and not on dialysis * Life-threatening allergy to radiographic contrast (unless treatment for allergy is tolerated or can be managed medically) * Currently enrolled in another investigational study protocol that could potentially confound the interpretation of the study endpoints/outcomes * Known dangerous anatomic variations leading to increased procedural risk or unsafe access for MMAE * Contraindicated for the use of PHIL™ liquid embolic system