Related Experiment Video

Updated: Jul 14, 2026

Comprehensive Endovascular and Open Surgical Management of Cerebral Arteriovenous Malformations
14:58

Comprehensive Endovascular and Open Surgical Management of Cerebral Arteriovenous Malformations

Published on: October 20, 2017

10.1K

Risk of Future Hemorrhage From Unruptured Brain Arteriovenous Malformations: The Multicenter Arteriovenous

Helen Kim1,2, Jeffrey Nelson1, Charles E McCulloch2

  • 1Center for Cerebrovascular Research, Department of Anesthesia and Perioperative Care, University of California, San Francisco.

JAMA Neurology
|October 6, 2025
PubMed
Abstract

Insights

The annual risk of intracranial hemorrhage (ICH) from unruptured brain arteriovenous malformations (AVMs) is lower than previously thought. Key risk factors for ICH include older age, associated aneurysms, and deep AVM location.

Area of Science:

  • Neurology
  • Neurosurgery
  • Epidemiology

Background:

  • Annual rates of first intracranial hemorrhage (ICH) from unruptured brain arteriovenous malformations (AVMs) are often cited as 2% to 4%.
  • Precise estimates and risk factors for ICH in unruptured brain AVMs are lacking, hindering informed treatment decisions.

Purpose of the Study:

  • To estimate the rates and identify risk factors for the first ICH in a large cohort of individuals with unruptured brain AVMs.

Main Methods:

  • The Multicenter Arteriovenous Malformation Research Study (MARS) analyzed data from 9 international cohorts (2 population-based, 7 referral-based) from 2017-2023.
  • Included 3030 participants with unruptured brain AVMs; primary outcome was time to first ICH.
  • Utilized Cox regression analysis with imputation for missing data, censoring at treatment, death, or last visit.

Main Results:

  • The annual ICH rate was 1.40 per 100 person-years (95% CI, 1.20-1.64), lower than commonly cited figures.
  • Significant independent risk factors for ICH included increasing age at diagnosis (P=.008), presence of associated aneurysms (P=.03), and deep AVM location (P=.01).
  • Seizures were present in 45% of participants; median AVM diameter was 3.1 cm.

Conclusions:

  • The actual annual ICH rate for unruptured brain AVMs is lower than clinical practice estimates.
  • Older age, associated aneurysms, and deep AVM location are significant risk factors for first ICH.
  • Findings can inform patient counseling regarding the natural history of unruptured brain AVMs.

More Related Videos

Double Direct Injection of Blood into the Cisterna Magna as a Model of Subarachnoid Hemorrhage10:34

Double Direct Injection of Blood into the Cisterna Magna as a Model of Subarachnoid Hemorrhage

Published on: August 30, 2020

11.3K
Endovascular Perforation Model for Subarachnoid Hemorrhage Combined with Magnetic Resonance Imaging MRI06:30

Endovascular Perforation Model for Subarachnoid Hemorrhage Combined with Magnetic Resonance Imaging MRI

Published on: December 16, 2021

4.3K

Related Concept Videos

Hemorrhagic Stroke l: Introduction01:17

Hemorrhagic Stroke l: Introduction

A hemorrhagic stroke is an acute neurological event that occurs when a weakened cerebral blood vessel ruptures, allowing blood to accumulate within or around the brain. The sudden release of blood forms a focal hematoma that increases intracranial pressure, displaces neural tissue, and can obstruct cerebrospinal fluid pathways. These effects may be compounded by intraventricular extension of the hemorrhage, cerebral edema, or compression of adjacent structures, all of which contribute to...
Hemorrhagic Stroke ll: Pathophysiology01:29

Hemorrhagic Stroke ll: Pathophysiology

A hemorrhagic stroke develops when a cerebral blood vessel ruptures, allowing blood to escape into the surrounding brain tissue, as in intracerebral hemorrhage (ICH), or into the subarachnoid space, as in subarachnoid hemorrhage (SAH). Because the skull is a rigid compartment, the sudden presence of extravascular blood rapidly increases intracranial pressure and compresses adjacent neural structures, leading to immediate tissue injury and impaired cerebral perfusion.Mass Effect and Primary...
Cerebral Edema ll: Pathophysiology01:22

Cerebral Edema ll: Pathophysiology

Vasogenic edema is a major form of cerebral edema characterized by abnormal accumulation of fluid in the brain’s extracellular space due to disruption of the blood–brain barrier (BBB). The BBB is a specialized structure composed of endothelial cells connected by tight junctions, supported by astrocytic endfeet and a basement membrane. Under normal conditions, it tightly regulates the movement of ions, proteins, and solutes between the bloodstream and brain parenchyma. When this barrier loses...