Chronic subdural hematomas (CSH) are collections of blood in the subdural space. CSH are becoming the most common cranial neurosurgical condition among adults, and a significant public health problem, due to an increasing use of anticoagulant and antiplatelet medication in an ageing population. Symptomatic CSH, or CSH with a significant mass effect, are treated surgically. However, recurrences are common (10 to 20%). Conservative management (medical) is used in patients who are asymptomatic or have minor symptoms. However, therapeutic failures, requiring surgical treatment, are common. The pathophysiology of CSH involves inflammation, angiogenesis, and clotting dysfunction. Self-perpetuation and rebleeding is thought to be caused by neo-membranes from the inflammatory remodeling of the dura-mater mainly fed by the distal branches of the middle meningeal artery (MMA). There are 13 ongoing registered RCTs in CSH, with the most common covering application of steroids, surgical techniques and tranexamic acid. Further to this, there are trials running on other pharmacological agents, and peri-operative management. Some industrial or academic trials are or will enroll in France in the next year in France. But to our best knowledge, none of these trials will the eventual benefits of the MMA embolization in both cases of medical and/or surgical management, and none will focus on the use of cyanoacrylates (CYA) for this purpose.

Preliminary case series and nonrandomized retrospective studies have suggested that MMA embolization alone or as adjuvant therapy to surgery can decrease recurrences.

The investigators hypothesize that in both conditions of conservative or surgical managements, endovascular embolization of patients with CSH significantly reduces the risk of recurrence of CSH. The investigators choose the CYA as liquid embolic agent because of the pain and cost of the use of Ethylen Vinyl alcohol copolymer (EVOH) agents and its simplicity to be used.

• Indication of surgical or conservative management will be decided by the neurosurgeon.
• Experimental arm:

CSH requiring hematoma removal will be surgically managed with a surgical technique applied depending on the surgeon's discretion.

Medical management will be adopted according to neurosurgeons habits. MMA embolization (on the CSH side or bilaterally if necessary) in the Experimental Arms will be performed with Cyanoacrylates and preferentially using conscious sedation or local anesthesia.

• Control arm: CSH requiring hematoma removal will be surgically managed with a surgical technique applied depending on the surgeon's discretion.

Medical management will be adopted according to neurosurgeons habits

• Primary and secondary end points will be assessed at 2 months+/- 1 month and assessed at 6 +/- 2 months. The blind items will be the mRS and the RACE score. The volume of the CSH will be semi-automatically assessed using the ABC/2 method and the estimated maximal thickness of the CSH on axial images.

Inclusion Criteria:

• Patient with a more than 10 mm CSH confirmed by NCCT
• CSH localized to convexity
• Patient aged 18 years or more at the time of the enrollment
• Patient beneficiary from health insurance

Exclusion Criteria:

• Any contraindication as required per angiogram procedure (severe renal failure ≥ 4, allergy…)
• Pre-existing severe disability resulting in baseline mRS score > 3
• Life expectancy of less than 6 months due to another cause than CSH
• Patient under legal protection or deprived of liberty by a judicial or administrative decision
• Pregnant or breastfeeding women
• Vulnerable persons unable to give consent

All collected data that underlie results in a publication

Data will be available beginning three years and ending fifteen years following the final study report completion.

Data access requests will be reviewed by the internal committee of Brest UH. Requestors will be required to sign and complete a data access agreement.