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  • Updated 11.08.2020
  • Released 06.09.2014
  • Expires For CME 11.08.2023

Arteriovenous malformations of the brain

Introduction

Overview

Cerebral arteriovenous malformations are congenital vascular malformations in the brain that are the underlying cause of 1% to 2% of all strokes, 3% of strokes in young adults, and around 10% of all subarachnoid hemorrhages (02; 38). They occur in about 0.1% of the population and represent one tenth of all intracranial aneurysms (38). Though mostly asymptomatic, these lesions come to clinical attention with a variety of neurologic presentations, including headaches, seizures, progressive neurologic deficits, or by incidental discovery (Derdeyn et al 2017). Short-term morbidity and mortality associated with arteriovenous malformations are low, but patients may do poorly in the long-term given the cumulative risk of hemorrhage. In determining the need for intervention, key morphologic and clinical characteristics are considered, such as age, size, location, vascular features, and most importantly, the risk of hemorrhage (04). In 2013, the first large-scale randomized clinical trial comparing medical and interventional management of unruptured brain arteriovenous malformations, the ARUBA trial, was published, showing that medical management alone remained superior to interventional therapy for the prevention of death or symptomatic stroke, even up to 5 years out (37). The purpose of this article is to discuss the clinical manifestations, pathophysiology, diagnosis, prognosis, and management of cerebral arteriovenous malformations.

Key points

• Cerebral arteriovenous malformations are congenital vascular malformations in the brain that result in direct connections between arteries and veins, without intervening capillary beds.

• They are an uncommon, but notable, cause of strokes and hemorrhages, especially in younger adults.

• Most cerebral arteriovenous malformations are asymptomatic and are discovered incidentally with neuroimaging.

• Cerebral arteriovenous malformations are reliably identified by CT and MR angiography, but conventional angiography remains the definitive diagnostic modality.

• Interventions for cerebral arteriovenous malformations include surgical resection, stereotactic radiation, and endovascular embolization.

Historical note and terminology

Vascular malformations of the central nervous system (CNS) have been described in the literature dating back to the 19th century. With advances in imaging modalities and microsurgical techniques, the understanding of and treatment options for these lesions have since grown. Modern categorization and nomenclature of CNS vascular malformations was established by McCormick in 1966, using histopathologic features to classify each lesion as a venous angioma, cavernous malformation, capillary telangiectasia, or arteriovenous malformation. The Spetzler-Martin grading system (Table 1) for cerebral arteriovenous malformations takes into account major factors influencing the risk of surgical resection and hemorrhage (55). It is the most commonly used grading system, helping clinicians make treatment decisions and offering a standardized classification terminology. A supplementary scoring system was published in 2010 taking into account additional components: age at resection, hemorrhage before resection, and diffuseness of the arteriovenous malformations nidus. This supplementary grading scale (also known as the Lawton-Young Grading System) was found to be more accurate at predicting neurologic patient outcome than the Spetzler-Martin system alone and further clarified surgical risk stratification (39). It was further validated and found to hold true, even with higher proportion of high-grade arteriovenous malformations; however, perforators play important role on the outcome (23).

Table 1. Spetzler-Martin Grading Scale for Arteriovenous Malformations

Characteristic

Number of points assigned

Size of arteriovenous malformation
Small (< 3 cm)
Medium (3 to 6 cm)
Large (> 6 cm)

1 point
2 points
3 points

Location
Non-eloquent site
Eloquent site

0 points
1 point

Pattern of venous drainage
Superficial only
Deep only

0 points
1 point

Score = sum of all categories, with lesions graded 1 to 5 based on total sum (eg, 1 point = grade 1).

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