Endovascular Treatment of Arteriovenous Malformations of the Infratentorial Compartment

21 Endovascular Treatment of Arteriovenous Malformations of the Infratentorial Compartment

Celene B. Mulholland, M. Yashar S. Kalani, and Felipe C. Albuquerque

Abstract

Endovascular treatment of arteriovenous malformations of the infratentorial compartment is generally part of a multifaceted approach, given the rarity and the complexity of these lesions, which often present with hemorrhage. Although not often the definitive treatment, cerebral angiography is essential for characterizing the lesion and guiding further treatment.

Keywords: embolization, endovascular therapy, hemorrhage, infratentorial, microsurgical resection, posterior fossa, stereotactic radiosurgery

Key Points

Infratentorial arteriovenous malformations (AVMs) account for 7 to 15% of arteriovenous malformations.
Patients with infratentorial AVMs are more likely to present with hemorrhage than patients with supratentorial AVMs.
Endovascular management may be key to surgical resection.

21.1 Introduction

Infratentorial arteriovenous malformations (AVMs) account for only 7 to 15% of cerebral AVMs. However, their risk of rupture is substantially higher than that of supratentorial AVMs, and 80% of symptomatic patients with infratentorial AVMs present with hemorrhage.¹^,² Thus, the rate of hemorrhage is twice that of supratentorial AVMs.³

Management of patients with ruptured and unruptured AVMs of the infratentorial compartment requires a multidisciplinary approach. Endovascular embolization is generally used in addition to either microsurgical resection or stereotactic radiosurgery.

This chapter examines the role of endovascular management in the treatment of infratentorial AVMs. In it, we review endovascular treatment for both ruptured and unruptured AVMs.

21.2 Materials and Methods

A MEDLINE-based search of the neurosurgical literature was performed to identify all articles published between January 1980 and July 2016 that included the keywords “posterior fossa arteriovenous malformation,” “infratentorial,” and “endovascular.” Retrieved articles were then reviewed to abstract the most up-to-date approaches to, and outcomes for, endovascular treatment of infratentorial AVMs.

Furthermore, we also drew upon our long-time institutional experience in treating numerous patients with infratentorial AVMs. Thus, the preoperative and postoperative angiograms and the intraoperative video that we have included reflect how AVMs are evaluated and treated within the clinical setting.

21.3 Results

A multitude of articles were identified and reviewed to extract relevant information about endovascular treatment. Articles that examined the role of endovascular treatment of posterior fossa AVMs were reviewed in depth. Articles that provided background epidemiologic data were also reviewed.

21.4 Discussion

Although posterior fossa AVMs compose only a small percentage of all AVMs, the propensity of patients with them to present with hemorrhage and neurologic decline highlights the importance of understanding the stages of their treatment. Endovascular embolization is generally considered an adjuvant to either microsurgical resection or stereotactic radiosurgery in the treatment of AVMs of the infratentorial compartment.⁴ Digital subtraction angiography is the gold standard for characterizing these lesions, and it is of utmost importance preoperatively.

Infratentorial AVMs are classified according to the Spetzler-Martin grading scale, which takes into consideration the size of the AVM, its eloquent location, and its venous drainage (► Fig. 21.1). Additionally, it is important to identify their location in the cerebellar hemisphere, tonsils, pontocerebellar region, vermis, or brainstem. The location and grade of an AVM will often dictate the most appropriate treatment modality. For example, some authors report that they do not treat brainstem AVMs with microsurgery and instead either observe or treat them with radiosurgery with or without prior embolization.⁵

Fig. 21.1 Artist’s illustration shows the arteriovenous malformation grading system developed by Spetzler and Martin. (Reproduced with permission from Spetzler RF, Ponce FA. A 3-tier classification of cerebral arteriovenous malformations. J Neurosurg 2011;114(March):842–849.)

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