Clinical Utility of Middle Meningeal Artery Embolization as an Adjunctive Treatment of Subdural Hematoma

Michelle Bravo, MD

At the 2024 American Neurological Association (ANA) Annual Meeting, held September 14-17 in Orlando, Florida, investigators from the University of Miami presented a case-report study of a 66-year-old man who presented with new onset daily headaches. The individual did not have any events of physical trauma, but showed signs of significant disability. In the initial workup, MRI of the brain with/without contrast showed a right sided subdural hematoma (SDH), signs of diffuse pachymeningeal enhancement, brain sagging, engorged venous plexus, and meningioma.

After not initially responding to an untargeted epidural blood patch (EBP), an MRI 3 months later revealed worsening right-sided SDH with maximal thickness of 27 mm and a 4.5 mm right to left midline shift. The study authors then administered a guided lumbar-thoracic blood patch, which gave temporary relief. Following that, the patient underwent right-side craniotomy for evacuation of the SDH, middle meningeal artery (MMA) embolization, followed by a repeat EBP. After undergoing these procedures, the patient had near resolution of his headaches.

Fifteen months post-op, he reported some intermittent mild headache but without clinical signs of a recurrent cerebrospinal fluid (CSF) leak. Follow-up imaging showed resolution of the SDH, further supporting the idea that MMA embolization may be considered as an adjunctive treatment in cases of SDH due to refractory CSF leaks. In addition, this case added to the limited reports in the neurosurgical literature demonstrating efficacy of MMA in treatment of SDH refractory to CSF leak.

Lead investigator Michelle Bravo, MD, an assistant professor of clinical neurology at the University of Miami, sat down following the meeting to discuss the rare case study and the takeaways from it. She spoke on the clinical utility of MMA embolization, the unique nature of CSF leaks, and the steps the neurosurgeons should take in these infrequent cases. She also provided comment on some of the unknowns surrounding SDH treatment, as well as some of the barriers for why MMA embolization is less frequently used.

NeurologyLive: For our audience, can you provide some background on MMA embolization?

Michelle Bravo, MD: Middle meningeal artery embolization is an emerging treatment for subdural hematomas in neurosurgery. Compared to traditional surgical interventions, it’s less invasive with lower morbidity and mortality. However, research on its application in treating subdural hemorrhages related to spontaneous intracranial hypotension (SIH) is limited, particularly in neurology and headache management. Most of the studies focus on subdural hematomas caused by trauma or other factors, which is what makes this case unique.

What are the greatest takeaways from a case report like this?

Spontaneous intracranial hypotension (SIH) is a relatively uncommon secondary disorder, but it’s likely underdiagnosed. It can lead to complications like subdural hemorrhage and even brain herniation or sagging. In this case, the patient developed a subdural hematoma due to SIH, which we treated not only with a blood patch to address the underlying condition but also with middle meningeal artery embolization. Additionally, the patient underwent a mini craniotomy to biopsy the meninges and evacuate the blood. The takeaway is that middle meningeal artery embolization, although not well studied in headache literature, can be a viable treatment for subdural hematomas related to SIH.

Do you feel that some within our community are still not comfortable turning to middle meningeal artery embolization since it’s relatively new?

That’s a great question. Middle meningeal artery embolization has emerged over the past five years in the neurosurgical world, with ongoing trials trying to identify the ideal patient population for this procedure. One of the challenges is that SIH is a rare diagnosis that’s difficult to recognize, as not every patient presents with the classic positional headache. Some patients may not have that component, or if the condition persists for a long time, the positional nature of the headache can disappear, leading to misdiagnosis. These diagnostic challenges are likely a barrier to applying this newer treatment modality.

What are the next steps toward building guidelines for managing CSF leak complications?

Great question. If a patient presents with a subdural hematoma and no clear history of trauma or vascular risk factors, spontaneous intracranial hypotension should be on the differential diagnosis. We have diagnostic criteria like the modified Dandy Walker criteria and the ICHD-3. However, diagnosing SIH can be difficult because symptoms and imaging results can vary. We often use the Bern score, which assesses MRI findings, and spinal imaging can reveal potential sources of leaks, like perineural cysts or epidural collections. While these guidelines may not always be straightforward, familiarity with the diagnostic criteria is important for all neurologists, given how common headache is as a symptom.

What are some unanswered questions regarding the treatment of subdural hematoma?

That's a great question. In cases of subdural hematomas related to SIH, the brain's sagging puts tension on the bridging veins, leading to tears and bleeds. Middle meningeal artery embolization not only seals off the source but may also reduce inflammation and further vessel tearing. It treats the underlying pathophysiology of the subdural hematoma in a less invasive manner, but there’s still more to learn about its long-term efficacy and applications.

REFERENCE
1. Bravo M, Starke RM, Pevsner NH, Monteith T. Middle meningeal artery embolization for treatment of subdural hematoma: report of a new case linked to spontaneous intracranial hypotension. Presented at: 2024 American Neurological Association (ANA) Annual Meeting.