Middle meningeal artery (MMA) embolisation for chronic subdural haematomas: rationale and design for the STOp Recurrence of MMA Bleeding (STORMM) randomised control trial-a study protocol

INTRODUCTION: Chronic subdural haematomas (cSDH) are common and can result in neurological impairment and reduced consciousness. Surgery is typically performed once neurological symptoms develop. Recent studies suggest that arteries nourished by the middle meningeal artery (MMA) may be responsible for haematoma progression and that MMA embolisation is clinically useful. There is less evidence that MMA embolisation can be an option for individuals without surgical treatment. We propose a multicentre study to investigate the efficacy of MMA embolisation to reduce cSDH recurrence and to improve outcomes.

METHODS AND ANALYSIS: cSDH patients with surgical indication will be randomised between the conventional management group (ie, surgery alone without MMA embolisation, Arm 1) and the surgery followed by MMA embolisation group (Arm 2) at multiple centres within Switzerland and Europe. The primary outcome will be the recurrence rate of cSDH. For that purpose, we estimate a minimum enrolment of 156 patients (alpha=0.05, power of 80%). Other major outcomes will include radiological parameters (volume, haematoma size, unilateral/bilateral presence) as well as clinical outcome scales and readmission rates. Outcomes will be recorded at admission and 6 weeks' and 6 months' follow-ups. Embolisation alone will be proposed to unoperated patients (surgical contraindication or refusal of surgery); the group of patients accepting and receiving embolisation (Arm 3) will additionally be compared with the group of untreated patients (Arm 4).

ETHICS AND DISSEMINATION: While it has been suggested that MMA embolisation reduces recurrence, no high-level evidence exists. As low risks exist with neuro-interventional procedures, there is equipoise for randomising patients to evaluate the potential benefits of MMA embolisation and to determine if these clearly outweigh the risks and costs. Peer-reviewed publications and presentations of the results at international meetings are planned.

TRIAL REGISTRATION NUMBER: The protocol is approved by the Geneva and Ticino Ethics Commission for Research (2023-00848) and is recorded on clinicaltrials.gov (NCT06163547).