Prospective MMA Embolization Registry (PRO-EMMA)

Background and Rationale Chronic subdural hematoma (cSDH) is a common condition, particularly in older adults, that can substantially impair patients' quality of life, functional independence, and neurological well-being. Blood accumulates in the subdural space and persists due to the formation of a highly vascularized outer hematoma membrane, which continuously rebleeds through fragile neovessels driven in large part by branches of the middle meningeal artery (MMA). This prevents spontaneous resolution and promotes hematoma growth. The standard treatment is surgical drainage, but recurrence rates reach up to 30%. Middle meningeal artery embolization (MMAE) targets this root cause by occluding the arterial supply to the hematoma membrane. Recent randomized controlled trials and meta-analyses have demonstrated high efficacy and safety of MMAE, both as standalone treatment and as adjunct to surgery. However, prospective data with standardized, protocol-driven follow-up capturing radiological response, functional status, quality of life at pre-specified time points, and predictive clinical and imaging parameters remain scarce.

Study-Specific Follow-Up Protocol

The MMAE procedure is performed according to clinical routine and standard of care. Study-specific additions consist solely of structured follow-up assessments:

• Functional Outcome and quality-of-life assessments using GCS, Markwalder score, mRS, GOS-E, and EQ-5D-5L at baseline (pre-intervention) and at days 30, 90, and 120 post-intervention, conducted by structured telephone or in-person interview
• Imaging follow-up by cranial CT within 7 days and at 3 months post-intervention.

Treatment decisions are made exclusively on the basis of clinical indication and are independent of study participation.

Data Collection

Data are documented in pseudonymized case report forms. The following domains are recorded:

• Clinical: patient history, GCS, comorbidities, anticoagulation/antiplatelet therapy, symptom course
• Radiological: hematoma volume, architecture, laterality, localization, midline shift, MMA caliber, anatomical MMA variants, foramen spinosum diameter, surgery
• Procedural: embolic agent, technical details, distribution of embolic agent, degree of distal penetration, complications
• Clinical: mRS, GOS-E, EQ-5D-5L, Markwalder score at each time point; re-intervention, recurrence, mortality, symptom course

Data Management and Quality Assurance All participants are assigned a pseudonymized study ID. The assignment list is stored separately and encrypted, with access restricted to authorized study personnel only. Data are stored exclusively on Charité servers (clinical data: 10 years; CT imaging data: 30 years), in compliance with DSGVO, BlnDSG, and applicable federal data protection regulations.

Data entries are checked against predefined plausibility and range rules; inconsistencies or out-of-range values are flagged and resolved before analysis. Source data verification is performed by comparing CRF entries against medical records and imaging reports. Missing values are documented and reported in the statistical analysis but will not be imputed.

Statistical Analysis The study is exploratory. Data will be analyzed using descriptive statistics with 95% confidence intervals. Bivariate correlation analyses (Pearson or Spearman as appropriate) and logistic regression models will be used to identify predictors of treatment success. Potential confounders include patient age, anticoagulation status, hematoma architecture, and procedural variables. A sufficient events-per-variable (EPV) ratio will be ensured in all regression models.

Pre-specified Predictor Variables

The following baseline and procedural variables will be analyzed as potential predictors of radiological and clinical treatment outcome:

• Hematoma morphology on baseline cranial CT, classified according to Nakaguchi et al. (homogeneous, laminar, trabecular, or separated).
• Middle meningeal artery caliber, anatomical variants, and foramen spinosum diameter on baseline imaging.
• Presence and type of anticoagulation or antiplatelet therapy at time of intervention.
• Degree of distal MMA penetration of embolic agent and type of embolic agent used.

Risks and Burden The primary additional burden from study participation consists of: (1) radiation from up to two study-mandated CT scans (within 7 days and at 3 months post-intervention), performed within diagnostically acceptable dose ranges; and (2) minimal time investment for structured interviews at days 30, 90, and 120 (approximately 10-15 minutes each). No additional medical interventions or modifications to clinical care are introduced by study participation.