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

PHIL™ (Precipitating Hydrophobic Injectable Liquid) Middle Meningeal Artery Embolization (MMAE) for First-Line Treatment of Chronic Subdural Hematoma (cSDH) IDE Trial (PHILFIRST)

This is a prospective, randomized, controlled, open-label, blinded endpoint (PROBE) clinical investigation in which patients with non-emergent chronic subdural hematoma (cSDH) requiring treatment will be randomized (1:1) to either initial surgical evacuation (Control Arm) or initial MMAE with PHIL™ (investigational arm).

Study Overview

• Status: Not yet recruiting
• Conditions: Chronic Subdural Hematomas
• Intervention / Treatment: Procedure: Surgical evacuation; Device: PHIL™ (Precipitating Hydrophobic Injectable Liquid)

• Study Type: Interventional
• Enrollment (Estimated): 475
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Amy Bowles; Phone Number: 714-482-8074; Email: amy.bowles@microvention.com
• Study Contact Backup: Name: Jennifer Tran; Phone Number: 949-678-1949; Email: jennifer.tran@terumo.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Surgical management; Control arm	Procedure: Surgical evacuation; Surgical evacuation of cSDH.
Experimental: PHIL embolic; Treatment arm	Device: PHIL™ (Precipitating Hydrophobic Injectable Liquid); Embolization of MMA with PHIL.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Primary Safety Endpoint	Incidence of mRS 0-2.	90 days post procedure
Primary Effectiveness Endpoint	Incidence of clinically indicated (as adjudicated by CEC) surgical evacuation of the target cSDH among subjects in the PHIL™ MMAE arm.	90 days post procedure

Secondary Outcome Measures

Outcome Measure	Time Frame
Death or major disabling stroke.	30-, 90-, and 180-days post-index procedure
The composite of: recurrent or residual chronic subdural hematoma on the target side measuring ≥ 10 mm; retreatment; or major disabling stroke, myocardial infarction, or death from neurologic causes.	180 days post procedure
Resolution of cSDH without retreatment.	90- and 180-days post procedure
Neurological death	90- and 180-days post procedure
Change in EQ-5D-5L from baseline	90- and 180-days post procedure
cSDH-related hospital re-admissions and re-admission days	90- and 180-days post procedure
Index hospitalization length of stay	post procedure
Neurological Events of Interest: minor stroke, major stroke, cSDH expansion, acute cSDH, mRS deterioration of 2 points or greater	90 days and 180 days post procedure

Collaborators and Investigators

• Sponsor: Microvention-Terumo, Inc.
• Investigators: Principal Investigator: David Fiorella, Stony Brook University

Study record dates

Study Major Dates

• Study Start (Estimated): December 31, 2026
• Primary Completion (Estimated): May 31, 2030
• Study Completion (Estimated): May 31, 2031

Study Registration Dates

• First Submitted: January 21, 2026
• First Submitted That Met QC Criteria: May 4, 2026
• First Posted (Actual): May 8, 2026

Study Record Updates

• Last Update Posted (Actual): May 8, 2026
• Last Update Submitted That Met QC Criteria: May 4, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Cerebrovascular Disorders; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Vascular Diseases; Cardiovascular Diseases; Wounds and Injuries; Pathologic Processes; Chronic Disease; Disease Attributes; Hemorrhage; Craniocerebral Trauma; Trauma, Nervous System; Intracranial Hemorrhages; Intracranial Hemorrhage, Traumatic; Pathological Conditions, Signs and Symptoms; Hematoma, Subdural; Hematoma; Hematoma, Subdural, Chronic
• Other Study ID Numbers: CL1108390

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes