A systematic review of middle meningeal artery embolization for minimally symptomatic chronic subdural haematomas that do not require immediate evacuation.

Introduction: Embolization of the Middle Meningeal Artery (EMMA) is an emerging treatment option for patients with Chronic Subdural Haematoma (CSDH). Questions: (1) Can EMMA change the natural history of untreated minimally symptomatic CSDH which do not require immediate evacuation? (2) What is the role of EMMA in the prevention of recurrence following surgical treatment? (3) Can the procedure be performed under local anaesthetic? Material and methods: Systematic literature review. No randomised clinical trials available on EMMA for meta-analysis. Results: Six unique large cohorts with more than 50 embolisations were identified (evidence: 3b-4). EMMA can control the progression of surgically naïve CSDH in 91.1-100% of the patients, in which haematoma expansion is halted, or the lesion decreases and resolves. Treatment failure requiring surgery occurs in 0-4.1% of the patients having EMMA as the primary and only treatment. Treatment failure requiring surgery goes up slightly to 6.8% if post-surgical patients are included. When EMMA is used as postsurgical adjunctive the risk of recurrence is 1.4-8.9% compared to 10-20% in surgical series. EMMA has minimal morbidity and it is feasible under local anaesthesia or slight sedation in the majority of cases. Conclusion: There is cumulative low-quality evidence in the literature that EMMA may be able to modify the natural course of the disease. It appears effective in controlling progression of CSDHs in patients having it as a primary standing alone treatment and it reduces the risk of recurrence and the need for surgical intervention in refractory postsurgical cases or as a postsurgical adjunctive treatment with minimal morbidity (recommendation: C).