This study presents the first pooled analysis of patients aged 80 or older undergoing MMAE for cSDH. Despite cSDH affecting the elderly and the rapid expansion of MMAE usage, this demographic remains underrepresented in literature, with only 86 patients identified in published real-world studies. MMAE demonstrated a favorable safety profile, showing low complication (5.8%) and in-hospital mortality (1.2%) rates, with most patients (81%) discharged home. Combined nBCA with coiling during MMAE correlated with higher odds of complete hematoma resolution, while antithrombotic use reduced those odds. Transradial access was used less frequently in patients > 90. In patients aged ≥ 90, rates of symptomatic collections were higher, the degree of midline shift was greater, and were often treated under conscious sedation via TFA. While radiographic outcomes were similar across age groups, patients aged 90 years or older faced a higher risk of prolonged hospitalization.

Accumulating histologic and anatomic evidence suggests that the fragility of neovasculature within the dural border cell layer plays a central role in cSDH. Damage to these capillaries leads to leakage of blood products into the potential space between the inner and middle dural layers, initiating a cyclical inflammatory and angiogenic response [10]. This paradigm shift from viewing cSDH as a passive venous bleed to an active, self-perpetuating inflammatory process has reshaped treatment approaches, particularly in older patients with cerebral atrophy or minor trauma [10,11,12]. Recent results from the EMBOLISE [13], STEM [14], and MEMBRANE [15] trials now provide Level 1 evidence supporting middle meningeal artery embolization (MMAE) as an effective adjunct in the management of chronic subdural hematoma (cSDH). While the MAGIC-MT [16] trial did not meet its primary efficacy endpoint, it did demonstrate a favorable safety profile with fewer serious adverse events in the MMAE arm. As the evidence base grows and MMAE is increasingly adopted in real-world practice, it remains critical to identify patient subgroups who may derive the greatest benefit, as well as those who may not respond favorably to embolization.

Patients aged 80 years or older remain significantly underrepresented in the trials on MMAE for cSDH. Patients over 90 are sometimes intrinsically excluded, and subgroup outcomes have not been reported. Across trials, mean ages in the MMAE arms ranged from 67.5 to 73 years (SD ~ 10.4–11.0). (Table 4) Assuming a normal distribution, only an estimated 11–27% of participants were ≥ 80 years old, below their representation in real-world cSDH populations, where individuals ≥ 80 account for nearly one-third of all cases. (Fig.8) This discrepancy highlights a key sampling bias and limits the generalizability of current trial findings to those aged ≥ 80 years, who bear the greatest disease burden yet remain the least studied. MMAE offers a compelling therapeutic profile for patients aged ≥ 80 years, who often present with higher anesthetic and surgical risk [17,18,19]. Unlike traditional operative evacuation, MMAE can be performed under local or moderate sedation, significantly reducing the physiological burden of general anesthesia, an important advantage in a population prone to cardiopulmonary complications, delirium, and postoperative deconditioning. Conscious sedation facilitates procedural safety while maintaining hemodynamic stability, even in patients with significant comorbidities [20, 21]. However, in our experience, one notable drawback of conscious sedation is the risk of patient motion during the procedure, particularly when embolic agents with meningeal irritating properties are used. Emerging strategies, such as pre-treating the MMA with analgesic agents prior to embolic administration, may help minimize discomfort and mitigate patient movement, although this approach remains under investigation. While the TRA was used less frequently in this age group, possibly due to anatomical challenges, vessel tortuosity, calcification or operator familiarity, it confers additional benefits, including enhanced procedural tolerance, earlier mobilization, and reduced length of stay [22,23,24]. Nonetheless, definitive conclusions regarding the optimal access route (TRA vs. TFA) or choice of anesthesia must be individualized based on patient-specific anatomical and clinical variables, highlighting the need for further research to guide treatment decision-making.

Proportion of patients aged ≥ 80 years estimated using reported means and standard deviations in the MMAE arms, assuming a normal distribution. Dashed line indicates real-world benchmark where ≥ 80-year-olds account for > 33% of cSDH cases

Antithrombotic use was associated with significantly decreased odds of complete hematoma resolution after MMAE in our cohort of patients aged ≥ 80. This observation is consistent with large multicenter studies in broader age groups and may be attributed to the fact that subdural collections resolve through gradual thrombosis over time [25]. Additionally, the elderly have higher vascular fragility and are more prone to rebleeding, which may may lead to re-accumulation of the collection. As such, optimizing peri-procedural antithrombotic management and carefully weighing the risks and benefits of therapy are essential.

Our pooled meta-analysis found that procedural complications after MMAE in patients aged 80 years or older remained low, with only 5.8% experiencing any complication and a 1.2% in-hospital mortality. Importantly, most patients returned home after the procedure. These findings align with prior meta-analyses and systematic reviews reporting pooled complication rates for MMAE in the 3–5% range, comparable to conventional surgery for cSDH [26]. The observed complications, including neurological deterioration, cranial nerve injury, vascular events, and rare access site complications, mirror those previously reported. Notably, severe complications such as stroke and blindness were exceedingly uncommon, and most adverse events reflected either procedural factors or the high baseline comorbidity burden typical of this population.

Recent multicenter studies have reported no significant differences in efficacy or safety among various embolic agents used for MMAE in chronic subdural hematoma [27]. However, our pooled analysis of patients aged 80 and older indicates that combining nBCA with coils is associated with significantly higher odds of complete hematoma resolution. This may be due to the complementary effects of each material: coils achieve proximal arterial occlusion, while nBCA enables deeper penetration into the subdural neomembranes, targeting the underlying neovascular supply. Given the ongoing debate and lack of randomized data on material combinations, further research is needed.

Although randomized trials support MMAE for cSDH, patients aged ≥ 80 have been consistently underrepresented, and those ≥ 90 were explicitly excluded, despite both groups bearing the highest disease burden. This highlights the need for higher-level evidence beyond the scope of this study. Nonetheless, our study offers the first pooled analysis centered on octogenarians and nonagenarians undergoing MMAE, drawing from a growing body of high-interest literature. It provides Level 3 evidence to inform treatment decisions [28] and emphasizes the need for future trials to prioritize appropriate age representation. This study is limited by its reliance on published reports, introducing risks of publication bias, selective reporting, and overlapping cohorts (full-text articles were reviewed to exclude duplicate populations). However, a key limitation of the current literature is the lack of granular data on factors such as laterality of the target vessel, aortic arch type, hematoma size, symptom severity, and rationale for selecting anesthesia or embolic agents, which are factors that can influence treatment outcomes. We recommend that future prospective studies systematically include these variables.