Case-Based Modules > Case 13 > Stage 4

At this point, we have to ask ourselves if there's data to support proceeding with MMA embolization for this left-sided SDH (admittedly with an acute/subacute component in addition to chronic). The best evidence available suggests that adjunctive MMA embolization for symptomatic subacute/chronic SDH can reduce hematoma recurrence rates as compared to surgery alone. For example, in the EMBOLISE trial, patients with subacute and chronic SDH were randomized to adjunctive MMA embolization + surgical evacuation vs. surgical evacuation alone. The primary endpoint was hematoma recurrence or progression that led to repeat surgery within 90 days. Occurrence of the primary endpoint was lower in the adjunctive MMA embolization arm (4.1% vs. 11.3%, for an ARR of 7.2%, p = 0.008). MAGIC-MT similarly randomized to adjunctive MMA embolization + usual care vs. usual care alone. Either way, this doesn't quite apply to our patient. If he goes on to experience clinical worsening that necessitates surgical evacuation, then it'd be very reasonable to pursue MMA embolization at that point.

What about MMA embolization as a primary treatment for symptomatic subacute/chronic SDH? That remains to be seen. There are two RCTs that are currently enrolling that hope to answer this question.

Wait, why does this even work? The classic teaching has been that epidural hematomas are caused by tearing of the middle meningeal artery, while subdural hematomas are caused by tearing of the bridging veins. The pathophysiology of chronic SDH is complex, and it's now thought to involve a repetitive cycle of bleeding, followed by inflammation and fibrinolytic products, followed by formation of neovascular membranes with friable vessels. It's thought that the neovascular membranes largely derive their blood supply from the middle meningeal artery. Thus, embolizing it would hopefully break this cycle, but it takes time for the blood products that already exist to be resorbed. At least, the lack of continued vascular supply to these membranes would give this resorption process a chance to catch up.

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