29 Chronic Subdural Hematoma Embolization

Joseph Carnevale, Justin Schwarz, Alexander Ramos, Jacob Goldberg, Thomas Link, and Jared Knopman

Abstract

Chronic subdural hematomas (cSDH) are a common pathology encountered routinely in clinical practice, particularly in the elderly population. This pathology is historically difficult to treat due to the comorbidities inherent in this patient population and the high rate of recurrence following surgical evacuation. The decision to manage conservatively with serial imaging versus surgical evacuation (twist drill craniotomy, burr-holes, or craniotomy) remains controversial and depends on patient symptomatology, radiographic findings, and patient comorbidities. A novel, multidisciplinary approach involving neurosurgeons and neurointerventionalists has recently shown promise in the treatment of cSDH. Embolization of the middle meningeal artery (MMA) is a safe procedure that has shown potential efficacy in decreasing the size of cSDH when performed as a stand-alone procedure and limiting cSDH recurrence following surgical evacuation.

Key words

chronic subdural hematoma – embolization – middle meningeal artery

29 Chronic Subdural Hematoma Embolization

29.1 Goals

Review and understand the symptomatology and natural history of chronic subdural hematomas (cSDH).
Review the current management strategies of cSDH and how it applies to the treatment decision for this pathology.
Critically analyze the limited literature that evaluates the utility of middle meningeal artery (MMA) embolization for cSDH.

29.2 Case Example

29.2.1 History of Present Illness

A 74-year-old female presents with a progressive headache and gait imbalance over 3 to 4 weeks. She endorses a fall from standing with head strike approximately 6 weeks ago while gardening with no loss of consciousness. The headache is predominantly right-sided, dull, constant, and not positional. The headache has been worsening over the last week, prompting her to seek medical care in the emergency department. She denies any weakness, numbness, tingling, seizures, or other significant neurologic complaints.

Past medical history: Hypertension, hyperlipidemia, hypothyroidism, coronary artery disease on aspirin 81 mg daily, ovarian cancer (no evidence of disease).

Past surgical history: Cesarean section (1971), hysterectomy and bilateral oophorectomy (1992).

Family history: Denies any relevant familial history.

Social history: One to two glasses of wine per week, former smoker, no illicit substance use.

Review of systems: As per the above.

Examination: Awake, alert, oriented to name, location, and date. Cranial nerves II—XII intact and symmetric, motor examination is grossly symmetric and strong, no drift.

Imaging studies: See Fig. 29.1a.

29.2.2 Treatment Plan

Given the size of the patient’s cSDH, treatment was recommended. The patient and her family adamantly wanted to avoid an open surgical procedure, including twist drill craniotomy, burr-hole drainage, and craniotomy. The patient was neurologi-cally intact and had only moderate headaches. MMA embolization was offered with the understanding that any worsening of symptoms or radiologic characteristics would warrant surgical evacuation. The patient underwent a right MMA embolization using polyvinyl alcohol particles under local anesthesia (Fig. 29.2). She was discharged home the next day following a stable noncontrast head computed tomography (CT).

29.2.3 Follow-up

The patient did very well after MMA embolization for her right cSDH. Following discharge on postprocedural day 1, the patient had gradual improvement of her headaches and gait. Her 2- and 4-week postprocedural follow-up head CTs demonstrated a reduction of her right cSDH, with complete resolution by 6 weeks postprocedure (Fig. 29.1). At her 6-week follow-up appointment, she had no headaches and was able to resume aspirin 81 mg daily for her coronary artery disease.

29.3 Case Summary

What are the general characteristics, symptomatology, and pathophysiology cSDH?

cSDH is an intracranial, extra-axial collection of chronic blood products that accumulates in the subdural space. It causes mass effect on the adjacent cerebral cortex, resulting in a variety of neurologic symptoms and signs. cSDH occur in 13.4 per 100,000 individuals annually, with a dramatic increase in patients older than 65 years. In the elderly population, the incidence is 58.1 per 1,00,000, a nearly 20-fold increase over the general population. ¹ ^, ² ^, ³ ^, ⁴ ^, ⁵ ^, ⁶ ^, ⁷ ^, ⁸ ^, ⁹ ^, ¹⁰ On presentation, patients and patient caretakers commonly complain of headache, confusion, language difficulty, gait instability, unilateral weakness, and/or seizures. cSDH can also be asymptomatic depending on the time course over which they develop and the degree of the patient’s brain atrophy. It is not uncommon for large cSDH to be fairly asymptomatic relative to their size. On noncontrast CT imaging, cSDH appear hypodense and are most often located along the cerebral convexity. Trace hyperdensities within cSDH are indicative of small acute blood products and commonly septations or membranes can be visualized on CT. Classic teaching states that SDH are due to tearing of bridging veins, which can be under tension in the elderly, atrophic brain. Current studies suggest that the pathophysiology of cSDH is more complex. Most cSDH begin as acute subdural hematomas, which evoke an inflammatory response. Within days, there is perihematoma inflammation and neovascularization with permeable endothelial gap junctions, which can lead to rehemorrhage or accumulation of new blood products causing cSDH enlargement. Simply removing the cSDH may only provide temporary clinical and radiographic improvement but not address the causative neovascularization that leads to reaccumulation. With our aging patient population, managing cSDH surgically requires durable and innovative measures to treat the underlying pathophysiology to curtail cSDH recurrence. ¹¹ ^, ¹² ^, ¹³ ^, ¹⁴ ^, ¹⁵ ^, ¹⁶ ^, ¹⁷ ^, ¹⁸ Recurrence of cSDH occurs frequently regardless of the surgical procedure, with rates ranging from 5 to 37% after evacuation. ¹
What role does MMA embolization play in management of cSDH?

MMA embolization has emerged as a safe, minimally invasive intervention for newly diagnosed or recurrent cSDH. By eliminating the neovascularization that contributes to cSDH by embolization, the progression and recurrence of cSDH is halted. ¹² ^, ¹³ ^, ¹⁴ ^, ¹⁵ ^, ¹⁶ ^, ¹⁷ ^, ¹⁸ ^, ¹⁹ ^, ²⁰ Early case reports and recent case series have demonstrated encouraging results, specifically in regard to early brain re-expansion and decreased hematoma recurrence. ²⁰ ^, ²¹ ^, ²² ^, ²³ These studies examine MMA embolization as either a primary, stand-alone treatment or an intervention following recurrence. In 2018, our group published the largest case series to date of MMA embolization for stand-alone treatment of newly diagnosed cSDH, prophylaxis following surgical evacuation, and for recurrence following surgical evacuation. ¹ Overall, current literature examining MMA embolization reports a notable decline in the rate of cSDH recurrence down to 3.6% with an exceptionally low rate of procedural complications. ¹⁰
What patient and radiographic factors would you consider when deciding on observation or treatment for cSDH?

Traditionally, cSDH management has been determined by cSDH size and patient symptomatology. If the cSDH is small and the patient is relatively asymptomatic, conservative management with observation and sequential imaging is favored. If the cSDH is very large or if there are neurologic deficits referable to the cSDH, surgical evacuation is usually more appropriate. There are multiple surgical options that vary in their level of invasiveness. The least invasive is twist drill craniotomy under moderate sedation, whereas the most invasive is a craniotomy under general anesthesia. The type of surgical procedure chosen is determined by the operator’s preference and by the patient’s history and symptomatology. In 1981, Markwalder et al presented a clinical criteria to classify cSDH based on patient symptoms. Grade 0 patients are asymptomatic, while Grade 1 patients are alert, oriented, with only mild symptoms, such as headache. Grade 2 patients are drowsy or disoriented, with neurologic deficits, including hemiparesis. Grade 3 patients are stuporous with severe focal signs such as hemiplegia, and Grade 4 patients are comatose. ²⁴ Typically, asymptomatic patients can be observed with serial imaging, as long as their cSDH are not of a radiographic size to warrant surgical evacuation.

It is important to understand the radiologic factors that could indicate a higher likelihood of cSDH worsening or recurrence following treatment. In 2001, Nakaguchi et al suggested a radiological classification of cSDH used in predicting rate of postoperative recurrence based on imaging characteristics of the hematoma. Recurrence was shown to be highest in the cSDH with acute bleeding along a vascular membrane, corresponding to the proposed pathophysiology of cSDH reaccu-mulation. ²⁵ ^, ²⁶ ^, ²⁷ In these cases, a potentially more invasive surgical evacuation could be pursued to attempt to eliminate these vascular membranes, or adjunct MMA embolization could be considered.

As with all candidates for surgery, the age and medical comorbidities of the patient need to be carefully considered in the context of the patient’s symptoms. Any patient with a neurologic deficit from a cSDH should undergo surgical evacuation. A patient with only mild-to-moderate symptoms, such as a headache, can be treated more conservatively with observation alone or potentially stand-alone MMA embolization. An elderly patient with multiple medical comorbidities on antiplatelet/anticoagulant medications and an asymptomatic or mildly symptomatic cSDH may be better served by close observation, MMA embolization alone, or twist drill craniotomy followed by MMA embolization, as opposed to undergoing a higher risk craniotomy.
When is MMA embolization appropriate?

Although surgical evacuation is the historical treatment of cSDH, MMA embolization could provide a significant benefit to patients by decreasing hematoma recurrence following evacuation or decreasing the need for surgical evacuation. Despite the early published success of MMA embolization in cSDH, this procedure remains controversial. The majority of the studies are small-volume, retrospective case series and, thus, are unable to show superiority of MMA embolization compared to surgical evacuation. A randomized, controlled clinical trial is needed to further define the promising role of MMA embolization in cSDH management.

In our institution we rigorously counsel patients and their families about the experimental nature of the procedure and perform stand-alone MMA embolization only on patients with Markwalder Grade 0 or 1 cSDH. Patients with higher Markwalder cSDH grade or with neurologic deficit from cSDH first undergo surgical evacuation followed by MMA embolization in an attempt to prevent recurrence.
What treatment wouldyou recommend for this patient’s chronic subdural hematoma?

The patient in the above case was recommended for standalone MMA embolization due to the patient’s intact neurologic status and relatively mild symptoms. Surgical evacuation alone or surgical evacuation with adjunctive MMA embolization is also reasonable, given the relatively large size of the cSDH. If stand-alone MMA embolization is performed, the patient and patient’s family must be thoroughly counseled on potential need for urgent surgical evacuation in the event of radiographic worsening or clinical deterioration.