Editing Cerebral arteriovenous malformation

{{Short description|Abnormal connection between the arteries and veins in the brain}}
{{Use mdy dates|date=March 2023}}
{{Infobox medical condition
| name            = Cerebral arteriovenous malformation
| image           = AVM grossly.jpg
| caption         = Large arteriovenous malformation of the [[parietal lobe]]
| symptoms        = 
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}}

A '''cerebral arteriovenous malformation''' ('''cerebral AVM''', '''CAVM''', '''cAVM''', '''brain AVM''', or '''BAVM''') is an abnormal connection between the [[Artery|arteries]] and [[vein]]s in the [[human brain|brain]]—specifically, an [[arteriovenous malformation]] in the [[cerebrum]].<ref>{{Cite web |title=Brain AVM (arteriovenous malformation) - Symptoms and causes |url=https://www.mayoclinic.org/diseases-conditions/brain-avm/symptoms-causes/syc-20350260 |access-date=2022-04-23 |website=[[Mayo Clinic]] |language=en}}</ref>

==Signs and symptoms==
The most frequently observed problems related to a cerebral [[arteriovenous malformation]] (AVM) are [[headache]]s and [[seizure]]s, [[Cranial nerve disease|cranial nerve afflictions]] including [[pinched nerve]] and [[palsy]],<ref>{{Cite web |last1=Al-Saiegh |first1=Fadi |last2=Hines |first2=Kevin |display-authors=1 |date=28 June 2019 |title=Oculomotor neuropathy from an unruptured arteriovenous malformation in the frontal operculum: A case report |url=http://surgicalneurologyint.com/surgicalint-articles/oculomotor-neuropathy-from-an-unruptured-arteriovenous-malformation-in-the-frontal-operculum-a-case-report-2/ |access-date=2019-07-31 |website=[[Surgical Neurology International]] |language=en-US}}</ref><ref name="pmid11571210"/> backaches, neckaches, and [[nausea]] from coagulated blood that has made its way down to be dissolved in the [[cerebrospinal fluid]]. Perhaps 15% of the population at detection are [[asymptomatic]].<ref name="pmid11571210"/> Other common symptoms are a pulsing noise in the head, progressive [[weakness]], [[numbness]] and vision changes as well as debilitating, excruciating [[pain]].<ref name="Mayo-Symptoms">{{Cite web|url=http://www.mayoclinic.com/health/brain-avm/DS01126/DSECTION=symptoms |title=Brain AVM (arteriovenous malformation)-Symptoms |author=Mayo Clinic staff |date=February 2009|publisher=Mayo Clinic |access-date=2010-05-18}}</ref><ref name="Medline"/>

In serious cases, [[blood vessel]]s rupture and cause bleeding within the [[Human brain|brain]] ([[intracranial hemorrhage]]).{{efn|Small AVMs cause hemorrhages more often than larger ones.<ref name=":1"/>}} In more than half of patients with AVM, this is the first symptom.<ref>{{Cite journal|last1=Perret|first1=G.|last2=Nishioka|first2=H.|date=1966-10-01|title=Report on the cooperative study of intracranial aneurysms and subarachnoid hemorrhage. Section VI. Arteriovenous malformations. An analysis of 545 cases of cranio-cerebral arteriovenous malformations and fistulae reported to the cooperative study|journal=Journal of Neurosurgery|volume=25|issue=4|pages=467–490|doi=10.3171/jns.1966.25.4.0467|issn=0022-3085|pmid=5925721}}</ref> Symptoms due to bleeding include [[loss of consciousness]], sudden and severe headache, nausea, [[vomiting]], [[Urinary incontinence|incontinence]], and [[blurred vision]], amongst others.<ref name="Mayo-Symptoms"/> Impairments caused by local brain-tissue damage on the bleed site are also possible, including seizure, one-sided weakness ([[hemiparesis]]), a loss of touch sensation on one side of the body and deficits in language processing ([[aphasia]]).<ref name="Mayo-Symptoms"/>  Ruptured AVMs are responsible for considerable mortality and morbidity.<ref name=":0">{{Cite book|title=100 Case Reviews in Neurosurgery|last=Jandial|first=Rahul|publisher=Elsevier|year=2017|isbn=978-0-323-35637-4}}</ref>

AVMs in certain critical locations may stop the circulation of the cerebrospinal fluid, causing it to accumulate within the skull and giving rise to a clinical condition called [[hydrocephalus]].<ref name="Medline">{{Cite web|url=https://www.nlm.nih.gov/medlineplus/ency/article/000779.htm |title=Arteriovenous malformation - cerebral |author1=David C. Dugdale |author2=Daniel B. Hoch |date=October 2008|publisher=ADAM |access-date=2010-05-18}}</ref> A stiff neck can occur as the result of increased pressure within the skull and irritation of the [[meninges]].<ref>{{Cite web|date=2021-09-21|title=Meningitis and stiff neck: Causes, treatment, and more|url=https://www.medicalnewstoday.com/articles/meningitis-stiff-neck|access-date=2021-11-06|website=[[Medical News Today]]|language=en}}</ref>

==Pathophysiology==
A cerebral AVM is an abnormal [[anastomosis]] (connection) between the [[arteries]] and [[vein]]s in the [[human brain|brain]] due to the lack of a [[capillary bed]], and is most commonly of [[prenatal]] origin.<ref name="Mayo-Causes">{{Cite web|url=http://www.mayoclinic.com/health/brain-avm/DS01126/DSECTION=causes |title=Brain AVM (arteriovenous malformation)-Causes |author=Mayo Clinic staff |date=February 2009|publisher=Mayo Clinic |access-date=2010-05-30}}</ref><ref name="Mouchtouris"/>

In normal [[cerebral circulation]], [[oxygenated blood|oxygen-enriched blood]] from the [[heart]] travels in sequence through smaller blood vessels going from arteries, to [[arteriole]]s and then [[capillaries]].<ref name="Mayo-Causes"/> Oxygen is removed in the capillaries to be used by the brain.<ref name="Mayo-Causes"/> After the oxygen is removed, blood reaches [[venules]] and later veins which will take it back to the heart and [[lung]]s.<ref name="Mayo-Causes"/> A cerebral AVM causes blood to be shunted directly from arteries to veins because the capillary bed is lacking, causing a disrupted [[Circulatory system|circulation]].<ref name="Mayo-Causes"/><ref name="Mouchtouris">{{cite journal|last1=Mouchtouris|first1=Nikolaos|last2=Jabbour|first2=Pascal M|last3=Starke|first3=Robert M|last4=Hasan|first4=David M|last5=Zanaty|first5=Mario|last6=Theofanis|first6=Thana|last7=Ding|first7=Dale|last8=Tjoumakaris|first8=Stavropoula I|last9=Dumont|first9=Aaron S|last10=Ghobrial|first10=George M|last11=Kung|first11=David|last12=Rosenwasser|first12=Robert H|last13=Chalouhi|first13=Nohra|title=Biology of cerebral arteriovenous malformations with a focus on inflammation|journal=Journal of Cerebral Blood Flow & Metabolism|date=19 November 2014|volume=35|issue=2|pages=167–175|doi=10.1038/jcbfm.2014.179|pmid=25407267|pmc=4426734}}</ref>

The overall annual incidence of [[haemorrhage]] from a ruptured AVM is 2-4%. Smaller AVMs have a greater propensity for haemorrhaging, whereas larger AVMs tend to more often cause seizures instead.<ref name=":02">{{Cite book |title=Schwartz's Principles of Surgery |edition=11th |publication-date=2019 |pages=1853}}</ref>

==Diagnosis==
[[File:Vein of galen ax direct AV.jpg|thumb|Axial image from computerized tomography angiogram showing arteriovenous communication in<br/>[[vein of Galen malformation]] ]]
[[File:Vein of Galen aneurysmal malformations.TIF|thumb|Vein of Galen [[thrombosis]] from [[Ventricular system|ventricular]] puncture, not to be mistaken for an [[aneurysm]]al malformation]]

A cerebral AVM diagnosis is established by [[neuroimaging]] studies after a complete neurological and physical examination.<ref name="Medline"/><ref name="Mayo-Diagnosis">{{Cite web|url=http://www.mayoclinic.com/health/brain-avm/DS01126/DSECTION=tests-and-diagnosis |title=Brain AVM (arteriovenous malformation)-Tests and diagnosis |author=Mayo Clinic staff |date=February 2009|publisher=Mayo Clinic |access-date=2010-05-18}}</ref> Three main techniques are used to visualize the brain and search for an AVM: [[computed tomography]] (CT), [[magnetic resonance imaging]] (MRI), and [[cerebral angiography]].<ref name="Mayo-Diagnosis"/> A CT scan of the head is usually performed first when the subject is symptomatic. It can suggest the approximate site of the bleed.<ref name="pmid11571210"/> MRI is more sensitive than CT in the diagnosis, and provides better information about the exact location of the malformation.<ref name="Mayo-Diagnosis"/> More detailed pictures of the tangle of blood vessels that compose an AVM can be obtained by using radioactive agents injected into the blood stream. If a CT is used in conjunction with an angiogram, this is called a computerized tomography angiogram; while, if MRI is used it is called [[magnetic resonance angiogram]].<ref name="pmid11571210"/><ref name="Mayo-Diagnosis"/>  The best images of a cerebral AVM are obtained through cerebral angiography. This procedure involves using a [[catheter]], threaded through an artery up to the head, to deliver a [[contrast agent]] into the AVM. As the contrast agent flows through the AVM structure, a sequence of {{Nowrap|[[X-ray]]}} images are obtained.<ref name="Mayo-Diagnosis"/>

==Grading==
=== Spetzler-Martin (SM) Grade ===

A common method of grading cerebral AVMs is the Spetzler-Martin (SM) grade.<ref>{{cite journal|last=Spetzler|first=R|author2=Martin N|s2cid=21796375|journal=J Neurosurg|year=1986|volume=65|pages=476–83|pmid=3760956|doi=10.3171/jns.1986.65.4.0476|title=A proposed grading system for arteriovenous malformations|issue=4|doi-access=}}</ref>  This system was designed to assess the patient's risk of neurological deficit after open surgical resection (surgical morbidity), based on characteristics of the AVM itself. Based on this system, AVMs may be classified as grades 1–5. This system was not intended to characterize risk of hemorrhage.<ref>{{Cite web |title=Spetzler Martin Grading Scale |url=https://www.bmc.org/spetzler-martin-grading-scale#:~:text=The%20Spetzler%20Martin%20Grading%20Scale,and%20low%20risk%20for%20surgery. |access-date=2022-04-23 |website=[[Boston Medical Center]]}}</ref>
{| class="wikitable"
|-
! AVM size !! Adjacent eloquent cortex !! Draining veins
|-
| < 3&nbsp;cm = 1 || Non-eloquent = 0 || Superficial only = 0
|-
| 3 – 6&nbsp;cm = 2 || Eloquent* = 1|| Deep veins = 1
|-
| > 6&nbsp;cm = 3 ||  ||
|}

"[[Eloquent cortex|Eloquent]]" is defined as areas within the brain that, if removed will result in loss of sensory processing or linguistic ability, minor paralysis, or paralysis.  These include the basal ganglia, language cortices, sensorimotor regions, and white matter tracts.<ref>{{Cite journal |last1=Jakola |first1=Asgeir S. |last2=Unsgård |first2=Geirmund |last3=Myrmel |first3=Kristin S. |last4=Kloster |first4=Roar |last5=Torp |first5=Sverre H. |last6=Lindal |first6=Sigurd |last7=Solheim |first7=Ole |date=2012-12-10 |title=Low Grade Gliomas in Eloquent Locations – Implications for Surgical Strategy, Survival and Long Term Quality of Life |journal=[[PLOS One]] |language=en |volume=7 |issue=12 |pages=e51450 |doi=10.1371/journal.pone.0051450 |issn=1932-6203 |pmc=3519540 |pmid=23251537|bibcode=2012PLoSO...751450J |doi-access=free }}</ref> Importantly, eloquent areas are often defined differently across studies<ref>{{Cite journal |last1=Satoer |first1=Djaina |last2=Visch-Brink |first2=Evy |last3=Dirven |first3=Clemens |last4=Vincent |first4=Arnaud |date=2016-01-01 |title=Glioma surgery in eloquent areas: can we preserve cognition? |url=https://doi.org/10.1007/s00701-015-2601-7 |journal=Acta Neurochirurgica |language=en |volume=158 |issue=1 |pages=35–50 |doi=10.1007/s00701-015-2601-7 |issn=0942-0940 |pmc=4684586 |pmid=26566782}}</ref> where deep cerebellar nuclei, cerebral peduncles, thalamus, hypothalamus, internal capsule, brainstem, and the visual cortex could be included.

The risk of post-surgical neurological deficit (difficulty with language, motor weakness, vision loss) increases with increasing Spetzler-Martin grade.<ref>{{Cite web |title=Brain arteriovenous malformations |url=https://www.uptodate.com/contents/brain-arteriovenous-malformations |access-date=2022-04-22 |website=UpToDate |publisher=[[Wolters Kluwer]] |quote=A higher Spetzler-Martin grading scale score correlates with increased risk of surgical morbidity and neurologic deficits.}}</ref>

=== Supplemented Spetzler-Martin (SM-supp, Lawton-Young) Grade ===

A limitation of the Spetzler-Martin Grading system is that it does not include the following factors: Patient age, hemorrhage, diffuseness of nidus, and arterial supply. In 2010 a new supplemented Spetzler-Martin system (SM-supp, Lawton-Young) was devised adding these variables to the SM system. Under this new system AVMs are classified from grades 1–10. It has since been determined to have greater predictive accuracy than SM grades alone.<ref>{{Cite journal|last1=Kim|first1=Helen|last2=Abla|first2=Adib A.|last3=Nelson|first3=Jeffrey|last4=McCulloch|first4=Charles E.|last5=Bervini|first5=David|last6=Morgan|first6=Michael K.|last7=Stapleton|first7=Christopher|last8=Walcott|first8=Brian P.|last9=Ogilvy|first9=Christopher S.|date=2015-01-01|title=Validation of the Supplemented Spetzler-Martin Grading System for Brain Arteriovenous Malformations in a Multicenter Cohort of 1009 Surgical Patients|journal=Neurosurgery|language=en|volume=76|issue=1|pages=25–33|doi=10.1227/neu.0000000000000556|issn=0148-396X|pmc=4270816|pmid=25251197}}</ref>
{| class="wikitable"
! rowspan="2" |Variable
! colspan="2" |Spetzler-Martin Grading Scale
! colspan="2" |Supplemental Grading Scale
|-
! Definition
! Points
! Definition
! Points
|-
| rowspan="3" |AVM size
| < 3&nbsp;cm
| 1
| 
| 
|-
| 3 – 6&nbsp;cm
| 2
| 
| 
|-
| > 6&nbsp;cm
| 3
| 
| 
|-
| Deep venous drainage
| No
| 0
| 
| 
|-
| 
| Yes
| 1
| 
| 
|-
| Eloquence
| No
| 0
| 
| 
|-
| 
| Yes
| 1
| 
| 
|-
!SM Grade Subtotal
!
!(1 - 5)
!
!
|-
| rowspan="3" |Age
| 
| 
| < 20 years
| 1
|-
| 
| 
| 20 – 40 years
| 2
|-
| 
| 
| > 40 years
| 3
|-
| rowspan="2" |Unruptured presentation
| 
| 
| No
| 0
|-
| 
| 
| Yes
| 1
|-
| rowspan="2" |Diffuse
| 
| 
| No
| 0
|-
| 
| 
| Yes
| 1
|-
! SM-Supp Grade Subtotal
! 
! 
! 
!  '''(1 – 5)'''
|-
!SM-Supp Total
!
!
!
!(1 – 10)
|}

==Treatment==
Treatment depends on the location and size of the AVM and whether there is bleeding or not.<ref name="Mayo-Treatment">{{Cite web|url=http://www.mayoclinic.com/health/brain-avm/DS01126/DSECTION=treatments-and-drugs |title=Brain AVM (arteriovenous malformation)-Treatments and drugs |author=Mayo Clinic staff |date=February 2009|publisher=Mayo Clinic |access-date=2010-05-18}}</ref>

The treatment in the case of sudden bleeding is focused on restoration of [[vital function]].<ref>{{Cite web |title=Arteriovenous Malformation - Conditions - For Patients - UR Neurosurgery |url=https://www.urmc.rochester.edu/neurosurgery/services/conditions/arteriovenous.aspx |access-date=2022-04-22 |website=[[University of Rochester Medical Center]]}}</ref>

===Medical===

Anticonvulsant medications such as [[phenytoin]] are often used to control seizure; medications or procedures may be employed to relieve intracranial pressure.  Eventually, curative treatment may be required to prevent recurrent hemorrhage. However, any type of intervention may also carry a risk of creating a neurological deficit.<ref>{{Cite web|url=http://www.aans.org/Patients/Neurosurgical-Conditions-and-Treatments/Arteriovenous-Malformations|title=AANS {{!}} Arteriovenous Malformations|website=www.aans.org|language=en|access-date=2018-02-03}}</ref>

=== Surgical ===
Surgical elimination of the blood vessels involved is the preferred curative treatment for many types of AVM.<ref name="Mayo-Treatment" /> Surgery is performed by a [[neurosurgeon]] who temporarily removes part of the skull ([[craniotomy]]), separates the AVM from surrounding brain tissue, and resects the abnormal vessels.<ref name="Mayo-Treatment" /> While surgery can result in an immediate, complete removal of the AVM, risks exist depending on the size and the location of the malformation. The AVM must be resected en bloc, for partial resection will likely cause severe hemorrhage.<ref name=":0" /> The preferred treatment of Spetzler-Martin grade 1 and 2 AVMs in young, healthy patients is surgical resection due to the relatively small risk of neurological damage compared to the high lifetime risk of hemorrhage. Grade 3 AVMs may or may not be amenable to surgery. Grade 4 and 5 AVMs are not usually surgically treated.<ref>{{cite journal|last=Starke|first=RM|journal=Br J Neurosurg|year=2009|volume=23|pages=376–86|pmid=19637008|doi=10.1080/02688690902977662|title=Treatment guidelines for cerebral arteriovenous malformation microsurgery|issue=4|s2cid=26286536|display-authors=etal}}</ref>

===Radiosurgical===

[[Radiosurgery]] has been widely used on small AVMs with considerable success.  The [[Gamma Knife]] is an apparatus used to precisely apply a controlled radiation dosage to the volume of the brain occupied by the AVM. While this treatment does not require an incision and craniotomy (with their own inherent risks), three or more years may pass before the complete effects are known, during which time patients are at risk of bleeding.<ref name="Mayo-Treatment" /> Complete obliteration of the AVM may or may not occur after several years, and repeat treatment may be needed. Radiosurgery is itself not without risk. In one large study, nine percent of patients had transient neurological symptoms, including headache, after radiosurgery for AVM. However, most symptoms resolved, and the long-term rate of neurological symptoms was 3.8%.<ref>{{cite journal|last=Flickinger|first=JC|journal=Int J Radiat Oncol Biol Phys|year=1998|volume=40|pages=273–278|pmid=9457809|doi=10.1016/S0360-3016(97)00718-9|title=Analysis of neurological sequelae from radiosurgery of arteriovenous malformations: How location affects outcome|issue=2|display-authors=etal}}</ref>

===Neuroendovascular therapy===

[[Embolization]] is performed by [[interventional neuroradiologists]] and the occlusion of blood vessels most commonly is obtained with [[ethylene vinyl alcohol]] copolymer ([[Onyx (interventional radiology)|Onyx]]) or [[n-butyl cyanoacrylate]]. These substances are introduced by a [[radiographically]] guided catheter, and block vessels responsible for blood flow into the AVM.<ref>{{Cite journal|last1=Ellis|first1=Jason A.|last2=Lavine|first2=Sean D.|date=2014-01-01|title=Role of Embolization for Cerebral Arteriovenous Malformations|journal=Methodist DeBakey Cardiovascular Journal|volume=10|issue=4|pages=234–239|doi=10.14797/mdcj-10-4-234|issn=1947-6094|pmc=4300062|pmid=25624978}}</ref> Embolization is frequently used as an adjunct to either surgery or radiation treatment.<ref name="Mayo-Treatment"/> Embolization reduces the size of the AVM and during surgery it reduces the risk of bleeding.<ref name="Mayo-Treatment"/> However, embolization alone may completely obliterate some AVMs. In high flow intranidal fistulas balloons can also be used to reduce the flow so that embolization can be done safely.<ref>Huded V. Endovascular balloon-assisted glue embolization of intranidal high flow fistula in brain AVM. J Neurosci Rural Pract 2013;4, Suppl S1:148-9</ref>

=== Risks ===
A first-of-its-kind controlled [[clinical trial]] by the [[National Institutes of Health]] and [[National Institute of Neurological Disorders and Stroke]] focuses on the risk of stroke or death in patients with an AVM who either did or did not undergo interventional eradication.<ref>{{Cite journal |last=Mohr |first=Jay Preston |date=June 4, 2015 |others=[[Columbia University]] |title=A Randomized Trial of Unruptured Brain Arteriovenous Malformations |url=https://clinicaltrials.gov/ct2/show/NCT00389181 |journal=[[ClinicalTrials.gov]] |access-date=2023-03-06}}</ref> Early results suggest that the invasive treatment of unruptured AVMs tends to yield worse results than the therapeutic (medical) management of symptoms.<ref name="aruba02">{{cite web |date=January 29, 2014 |title=A Randomized Trial of Unruptured Brain Arteriovenous Malformations (ARUBA) |url=http://www.ninds.nih.gov/news_and_events/news_articles/ARUBA_trial_results.htm |archive-url=https://web.archive.org/web/20160704222521/http://www.ninds.nih.gov/news_and_events/news_articles/ARUBA_trial_results.htm |archive-date=2016-07-04 |access-date=2023-03-06 |website=[[National Institute of Neurological Disorders and Stroke]]}}</ref>{{efn|According to established medical research, however, the chance of eventual hemorrhage increases over time.<ref name=":1" />}} Because of the higher-than-expected [[experimental event rate]] (e.g. stroke or death), patient enrollment was halted by May 2013, while the study intended to follow participants (over a planned 5 to 10 years) to determine which approach seems to produce better long-term results.<ref name="aruba02" />

==Prognosis==
{{See also|Intracranial hemorrhage}}

The main risk is intracranial hemorrhage. This risk is difficult to quantify since many patients with asymptomatic AVMs will never come to medical attention. Small AVMs tend to bleed more often than do larger ones, the opposite of [[cerebral aneurysm]]s.<ref>{{cite journal|last=Crawford|first=PM|journal=J Neurol Neurosurg Psychiatry|year=1986|volume=49|pages=1–10|pmid=3958721|doi=10.1136/jnnp.49.1.1|title=Arteriovenous malformations of the brain: natural history in unoperated patients|issue=1|pmc=1028639|display-authors=etal}}</ref>  If a rupture or bleeding incident occurs, the blood may penetrate either into the brain tissue ([[cerebral hemorrhage]]) or into the [[subarachnoid space]], which is located between the sheaths (meninges) surrounding the brain ([[subarachnoid hemorrhage]]). Bleeding may also extend into the [[ventricular system]] ([[intraventricular hemorrhage]]). Cerebral hemorrhage appears to be most common.<ref name="pmid11571210" />
One long-term study (mean follow up greater than 20 years) of over 150 symptomatic AVMs (either presenting with bleeding or seizures) found the risk of cerebral hemorrhage to be approximately 4% per year, slightly higher than the 2–4% seen in other studies.<ref>{{cite journal|last=Ondra|first=SL|journal=J Neurosurg|year=1990|volume=73|pages=387–391|pmid=2384776|doi=10.3171/jns.1990.73.3.0387|title=The natural history of symptomatic arteriovenous malformations of the brain: A 24-year follow-up assessment|issue=3|display-authors=etal}}</ref><ref name=":1" /> The earlier an AVM appears, the more likely it is to cause hemorrhage over one's lifetime; e.g. (assuming a 3% annual risk), an AVM appearing at 25 years of age indicates a 79% lifetime chance of hemorrhage, while one appearing at age 85 indicates only a 17% chance.<ref name=":1">{{cite book|last=Greenberg|first=Mark|title=Handbook of Neurosurgery|url=https://archive.org/details/handbookofneuros0006gree/page//|edition=6th|year=2006|orig-year=1990|publisher=[[Thieme Medical Publishers|Thieme]]|pages=835–837}}</ref> Ruptured AVMs are a significant source of morbidity and mortality; following a rupture, as many as 29% of patients will die, with only 55% able to live independently.<ref name=":0" />

==Epidemiology==
The annual new detection rate [[incidence (epidemiology)|incidence]] of AVMs is approximately 1 per 100,000 a year. The [[point prevalence]] in adults is approximately 18 per 100,000.<ref name="pmid11571210">{{Cite journal|vauthors=Al-Shahi R, Warlow C |title=A systematic review of the frequency and prognosis of arteriovenous malformations of the brain in adults |journal=Brain |volume=124 |issue=Pt 10 |pages=1900–26 |date=October 2001 |pmid=11571210 |doi= 10.1093/brain/124.10.1900|doi-access=free }}</ref> AVMs are more common in males than females, although in females [[pregnancy]] may start or worsen symptoms due to the increase in [[blood flow]] and [[blood volume|volume]] it usually brings.<ref name="Mayo-RF">{{Cite web|url=http://www.mayoclinic.com/health/brain-avm/DS01126/DSECTION=risk-factors |title=Brain AVM (arteriovenous malformation)-Risk factors |author=Mayo Clinic staff |date=February 2009|publisher=Mayo Clinic |access-date=2010-05-30}}</ref> There is a significant preponderance (15–20%) of AVM in patients with [[hereditary hemorrhagic telangiectasia]] (Osler–Weber–Rendu syndrome).<ref name=":1" />

==References==
'''Footnotes'''
{{notelist}}

'''Citations'''
{{Reflist}}

{{Commons category|Cerebral arteriovenous malformation}}
{{Medical resources
|  DiseasesDB     = 2224
|  ICD11          = {{ICD11|8B22.40}}
|  ICD10          = {{ICD10|Q28.2}}
|  ICD9           = {{ICD9|747.81}}
|  ICDO           =
|  OMIM           = 108010
|  MedlinePlus    = 000779
|  eMedicineSubj  = neuro
|  eMedicineTopic = 21
|  eMedicine_mult = {{eMedicine2|article|252426}} {{eMedicine2|article|337220}}
|  MeshID         = D002538
}}
{{Congenital vascular defects}}

{{DEFAULTSORT:Cerebral Arteriovenous Malformation}}
[[Category:Anatomical pathology]]
[[Category:Congenital vascular defects]]