Meningioma Embolization

19 Meningioma Embolization

Joshua S. Catapano, Rami 0. Almefty, Nader Sanai, Felipe Albuquerque, and Andrew F. Ducruet

Abstract

Preoperative embolization of meningiomas remains controversial and is often dependent on surgeon preference. Endovascu-lar techniques have advanced significantly over the past several decades, making embolization of meningiomas safer and more effective. However, the medical literature regarding the safety and efficacy of preoperative embolization of meningiomas is scarce. It is therefore imperative to examine the landmark papers in the field to acquire a thorough understanding of the subject and to form an evidence-based opinion to facilitate decision-making on the use of embolization in the treatment of meningiomas.

Keywords: embolization, meningiomas, neurointerventional procedures, Onyx, tumor

19.1 Goals

1. Review the medical literature on preoperative embolization of meningiomas.

2. Critically analyze the medical literature on the preoperative embolization of meningiomas.

3. Provide recommendations for preoperative embolization of meningiomas.

19.2 Case Example

19.2.1History of Present Illness

A 46-year-old woman presented to the emergency room with a new onset of a generalized tonic-clonic seizure and was found on magnetic resonance imaging (MRI) to have a right frontal operculum extra-axial mass consistent with a large meningioma with extensive surrounding edema and brain compression (▶ Fig. 19.1a-e). She denied any other neurological complaints, including loss of consciousness, numbness, weakness, and speech/vision difficulty.

Medical history: Denied a history of cancer or any other pertinent history.

Surgical history: Previous tonsillectomy.

Family history: Denied a history of previous central nervous system tumors.

Social history: Denied tobacco, alcohol, and illicit drug use.

Review of systems: As per the above.

Neurological examination: Unremarkable.

Imaging studies: See ▶ Fig. 19.1 and ▶ Fig. 19.2.

19.2.2 Treatment Plan

The patient consented to a preoperative embolization followed by surgical resection the next morning. A distal branch of the right middle meningeal artery (MMA) was the primary vascular supply to the lesion (▶ Fig. 19.1d, e). Successful transcatheter, transarterial embolization with Onyx (Medtronic pic) within the right MMA was performed, without any evidence of residual tumor vascularity or nontarget embolization (▶ Fig. 19.2a, b). The patient experienced no complications after embolization and subsequently underwent a right-sided craniotomy for complete resection of the tumor (▶ Fig. 19.2c, d).

19.2.3 Follow-up

The patient initially woke from surgery with word-finding difficulties, which resolved on postoperative day 1. The patient was discharged home on postoperative day 2 without neurological deficits and was doing well on follow-up.

19.3 Case Summary

1. What factors would you consider when deciding on preoperative embolization of meningiomas?

Preoperative embolization of meningiomas may facilitate surgical resection.¹^,²^,³^,⁴ Several studies have described reduced blood loss, shorter length of operative time, and a greater capability of achieving gross total resections of skull base and large meningiomas.¹^,²^,³^,⁴^,⁵^,⁶ However, preoperative embolization of such lesions does pose the risk of severe complications, including stroke and hemorrhage.¹^,⁷ The risks and benefits of preoperative embolization must be carefully weighed. Preoperative embolization has been beneficial in patients with anterior skull base and large supratentorial lesions.¹^,⁸^,⁹ In these patients, preoperative embolization causes central softening and necrosis, which creates a plane between the adjacent brain and tumor, making removal simpler and safer for adjacent vital structures.¹^,⁸^,⁹ Furthermore, highly vascular giant convexity tumors with a complex blood supply may benefit the most from preoperative embolization because of a decrease in vascularity and a reduction of intraoperative blood loss.¹ The majority of skull base meningiomas are supplied by branches from the external carotid artery (ECA), which allows for safer catheterization and embolization with a low risk of neurological morbidity. However, careful attention is necessary to avoid common extracranial-intracranial anastomoses and ECA branches with distal cranial nerve supply.¹⁰^,¹¹ Cases where the internal carotid artery supplies the majority of the vascular supply of a meningioma are generally poor cases for preoperative embolization, as the majority of the supply generally arises either from the ophthalmic or ethmoidal vessels, which are largely accessible early in surgery, or from the meningohypophyseal trunk, which can be challenging to catheterize safely.¹⁰ Preoperative embolization is thought to be valuable in rare complex meningiomas that are associated with a vascular lesion or aneurysm, where the vascular lesion or aneurysm can be dealt with before surgery, making resection safer.¹^,¹²^,¹³^,¹⁴ Another example where preoperative embolization is useful is in orbital lesions, where embolization theoretically reduces intraoperative blood loss, which improves visualization and allows for safer resection.¹^,⁷

Fig. 19.1 (a) Axial T2 magnetic resonance imaging (MRI) showing an avidly enhancing, T2 isointense extra-axial mass overlying the right frontal operculum, with a dural tail. The mass has imaging characteristics of a large meningioma, measuring 4.2 x4.3×2.3 cm (anteroposterior x craniocaudalx transverse). There is a large arterial feeder overlying the superior, anterior, and inferior aspects of the meningioma, (b) Sagittal T1 MRI with contrast, (c) Coronal T1 MRI with contrast, (d) Pre-embolization right external carotid angiogram (RECA) injection, posteroanterior view, showing highly vascular tumor with main supply from the right middle meningeal artery, (e) Pre-embolization lateral view of RECA injection. (Used with permission from Barrow Neurological Institute, Phoenix, Arizona.)

2. What technical considerations were important for embolization of this patient’s lesion?

In the case described, the meningioma was a large, highly vascular, operculum lesion, with a blood supply from the MMA of the ECA. Because of the size and vascularity of the lesion, preoperative embolization was deemed beneficial to reduce intraoperative blood loss and create a necrotic core, thus facilitating a safer gross total resection. Although catheterization and embolization of the MMA is technically feasible and carries a low risk of neurological morbidity, careful attention was paid to avoiding occlusion of the petrosal branch of the MMA, which supplies the facial nerve.¹¹ Embolization was performed with ethylene vinyl alcohol copolymer Onyx, which is a liquid agent that is dissolved in dimethyl sulfoxide to create a low precipitation in the blood at the site of injection, allowing for deep intratumoral vessel penetration.⁶^,¹⁵^,¹⁶ Hence, Onyx is thought to aid in devascularization of larger lesions, as in the case described. Furthermore, Onyx is less adhesive than other liquid embolizing agents such as n-butyl cyanoacrylate (NBCA), reduces the risk of mi-crocatheter entrapment or fracture, and allows for longer injections with more control angiograms.¹⁶^,¹⁷

19.4 Level of Evidence

Given the patient’s lesion location, size, and vascular pedicle, preoperative embolization of the tumor was deemed beneficial (Class III, Level of Evidence C).

19.5 Landmark Papers

Manelfe C, Guiraud B, David J, et al. Embolization by catheterization of intracranial meningiomas [In French]. Rev Neurol (Paris) 1973;128:339-351.

In 1973, Manelfe et al ¹⁸ first reported the use of preoperative embolization by catheterization of intracranial meningiomas. The authors reported a series of five meningiomas treated via embolization with fragments of Spongel (Magic srl). This series included three convexity and two skull base lesions embolized, each with primary feeders from the ECA. Four of the patients were subsequently operated on within 3 to 13 days. One patient did not undergo resection because the tumor was deemed highly malignant; however, that patient was described as making enough progress to resume daily activities 6 months post-embolization. The authors described a practically bloodless operation, which greatly facilitated the resection of the lesions, in the four patients with resection. In pathological specimens, each lesion was confirmed to have been embolized, with fragments of Spongel visible in intratumoral capillaries. The authors concluded that percutaneous catheter embolization is beneficial for large meningiomas, particularly lesions located in the skull base with feeders from the ECA because this practice greatly decreased the risk of operative hemorrhage.