title: Brain arteriovenous malformations.
abstract: An arteriovenous malformation is a tangle of dysplastic vessels (nidus) fed by arteries and drained by veins without intervening capillaries, forming a high-flow, low-resistance shunt between the arterial and venous systems. Arteriovenous malformations in the brain have a low estimated prevalence but are an important cause of intracerebral haemorrhage in young adults. For previously unruptured malformations, bleeding rates are approximately 1% per year. Once ruptured, the subsequent risk increases fivefold, depending on associated aneurysms, deep locations, deep drainage and increasing age. Recent findings from novel animal models and genetic studies suggest that arteriovenous malformations, which were long considered congenital, arise from aberrant vasculogenesis, genetic mutations and/or angiogenesis after injury. The phenotypical characteristics of arteriovenous malformations differ among age groups, with fistulous lesions in children and nidal lesions in adults. Diagnosis mainly involves imaging techniques, including CT, MRI and angiography. Management includes observation, microsurgical resection, endovascular embolization and stereotactic radiosurgery, alone or in any combination. There is little consensus on how to manage patients with unruptured malformations; recent studies have shown that patients managed medically fared better than those with intervention at short-term follow-up. By contrast, interventional treatment is preferred following a ruptured malformation to prevent rehaemorrhage. Management continues to evolve as new mechanistic discoveries and reliable animal models raise the possibility of developing drugs that might prevent the formation of arteriovenous malformations, induce obliteration and/or stabilize vessels to reduce rupture risk. For an illustrated summary of this Primer, visit: http://go.nature.com/TMoAdn.
authors.affiliation: Department of Neurological Surgery, University of California, 505 Parnassus Avenue, M780, San Francisco, California 94143, USA.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Lawton
authors.affiliation: Department of Neurological Surgery, University of California, 505 Parnassus Avenue, M780, San Francisco, California 94143, USA.
authors.forename: W Caleb
authors.initials: WC
authors.lastname: Rutledge
authors.affiliation: Department of Anesthesia and Perioperative Care, University of California, San Francisco, USA.
authors.forename: Helen
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Neurology, APHP Hôpital Lariboisière, Paris, France, and DHU Neurovasc, Université Paris Diderot, Paris, France.
authors.forename: Christian
authors.initials: C
authors.lastname: Stapf
authors.affiliation: Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Whitehead
authors.affiliation: Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.
authors.forename: Dean Y
authors.initials: DY
authors.lastname: Li
authors.affiliation: Department of Medical Imaging, University of Toronto, Ontario, Canada.
authors.forename: Timo
authors.initials: T
authors.lastname: Krings
authors.affiliation: Department of Medical Imaging, University of Toronto, Ontario, Canada.
authors.forename: Karel
authors.initials: K
authors.lastname: terBrugge
authors.affiliation: Neurological Surgery, University of Pittsburgh, Pennsylvania, USA.
authors.forename: Douglas
authors.initials: D
authors.lastname: Kondziolka
authors.affiliation: Clinical Medicine, Macquarie University, Sydney, Australia.
authors.forename: Michael K
authors.initials: MK
authors.lastname: Morgan
authors.affiliation: Division of Neurological Surgery, Barrow Neurological Institute, Phoenix, Arizona, USA.
authors.forename: Karam
authors.initials: K
authors.lastname: Moon
authors.affiliation: Division of Neurological Surgery, Barrow Neurological Institute, Phoenix, Arizona, USA.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Spetzler
mesh_terms: D000328:Adult; D000818:Animals; D001165:Arteriovenous Malformations / Q000150:complications / Q000000981:diagnostic imaging / Q000628:therapy; D001921:Brain / Q000098:blood supply / Q000000981:diagnostic imaging; D002543:Cerebral Hemorrhage / Q000209:etiology; D002648:Child; D005260:Female; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000150:complications / Q000000981:diagnostic imaging / Q000628:therapy; D008297:Male; D010641:Phenotype; D012422:Rupture, Spontaneous / Q000209:etiology; D055815:Young Adult