Arteriovenous malformation

From Wikipedia, the free encyclopedia

Arteriovenous malformation
Classification and external resources
ICD-10	Q27.3, Q28.0, Q28.2
ICD-9	747.6, 747.81
DiseasesDB	15235
MedlinePlus	000779
eMedicine	topic list
MeSH	D001165

Arteriovenous malformation or AVM is an abnormal connection between veins and arteries, usually congenital. This pathology is widely known because of its occurrence in the central nervous system, but can appear in any location.

The genetic transmission patterns of AVM, if any, are unknown. AVM is not generally thought to be an inherited disorder, unless in the context of a specific hereditary syndrome.

Contents 1 Signs and symptoms 2 Pathophysiology 3 Diagnosis 4 Treatment 5 Epidemiology 6 Society and culture 6.1 Cases in fiction 7 Research directions 8 See also 9 References 10 External links

[edit] Signs and symptoms

Symptoms of AVM vary according to the location of the malformation. Roughly 88% ^[1] of people affected with AVM are asymptomatic; often the malformation is discovered as part of an autopsy or during treatment of an unrelated disorder (called in medicine an incidental finding); in rare cases its expansion or a micro-bleed from it can cause epilepsy, deficit or pain.

The most general symptoms include headache and epilepsy, with more specific symptoms occurring that normally depend on the location of the malformation and the individual. Such possible symptoms include:^[2]

• Difficulties with movement or coordination, including muscle weakness and even paralysis;
• vertigo (dizziness);
• Difficulties of speech (dysarthria) and communication, such as alogia;
• Difficulties with everyday activities, such as apraxia;
• Abnormal sensations (numbness, tingling, or spontaneous pain);
• Memory and thought-related problems, such as confusion, dementia or hallucinations.

[edit] Pathophysiology

Arteries and veins are part of the human cardiovascular system. Normally, the arteries in the vascular system carry oxygen-rich blood. Structurally, arteries divide and sub-divide repeatedly, eventually forming a sponge-like capillary bed. Blood moves through the capillaries, giving up oxygen and taking up waste products, including CO₂, from the surrounding cells. Capillaries in turn successively join together to form veins that carry blood away. The heart acts to pump blood through arteries and uptake the venous blood.

An AVM lacks the dampening effect of capillaries on the blood flow; it also causes the surrounding area to be deprived of the functions of the capillaries - removal of CO2 and delivery of nutrients to the cells. The resulting tangle of blood vessels, often called a nidus (Latin for "nest") has no capillaries and abnormally direct connections between high-pressure arteries and low-pressure veins. It can be extremely fragile and prone to bleeding. The resultant sign, audible via stethoscope, is a rhythmic, whooshing sound caused by excessively rapid blood flow through the arteries and veins. It has been given the term "bruit", French for noise. On some occasions a patient with a brain AVM may become aware of the noise, which can compromise hearing and interfere with sleep in addition to causing psychological distress.

[edit] Diagnosis

AVMs can occur in various parts of the body

• brain, causing a cerebral arteriovenous malformation
• spleen^[3]
• lung^[4]
• kidney^[5]
• spinal cord^[6]
• liver^[7]
• intercostal space^[8]
• iris^[9]
• spermatic cord^[10]

AVMs may occur in isolation or as a part of another disease (e.g. Von Hippel-Lindau disease or hereditary hemorrhagic telangiectasia).

Bleeding from an AVM can be devastating, particularly in the brain. It can cause severe and often fatal strokes. If a cerebral AVM is detected before a stroke occurs, usually the arteries feeding blood into the nidus can be closed off to avert the danger.

[edit] Treatment

Treatment can be symptomatic, or it can involve surgery or radiation therapy.^[2] Embolization, that is, cutting off the blood supply to the AVM with coils or particles or glue introduced by a radiographically guided catheter, can be used in addition to either, but is rarely successful in isolation.

[edit] Epidemiology

An estimated 300,000 Americans have AVMs, of whom 12% (approximately 36,000) will exhibit symptoms of greatly varying severity.^[2]

[edit] Society and culture

• On December 13, 2006, Senator Tim Johnson was diagnosed with AVM and treated at George Washington University Hospital.^[11]

[edit] Cases in fiction

• The plot of William Finn's 1998 Off-Broadway musical A New Brain revolves around the main character's battle with AVM.
• The character Nate Fisher on the HBO television show Six Feet Under suffers from AVM.
• Patients with AVM appeared in an episode of the series House entitled "DNR" as well as in a fictional British medical show called Harley Street.
• The protagonist of Robert J. Sawyer's novel Mindscan suffers from an AVM that threatens to reduce him to a permanent vegetative state.
• In an episode of TNT's HawthoRNe entitled "The Sense of Belonging" patient Amy Johnson suffers from this disorder, as well as an unmentioned congenital heart defect.

[edit] Research directions

Despite many years of research, the central question of whether to treat AVMs has not been answered. All treatments, whether involving surgery, radiation, or drugs, have risks and side-effects. Therefore it might be better in some cases to avoid treatment altogether and simply accept a small risk of coming to harm from the AVM itself. This question is currently being addressed in clinical trials^[12].

[edit] See also

• Foix-Alajouanine syndrome

[edit] References

[edit] External links

• AVM Support Groups from the DMOZ Open Directory.
• University of California San Francisco AVM research.

v • d • e Congenital vascular defects (Q25-Q28, 747) Great arteries/ other arteries Aorta Patent ductus arteriosus · Coarctation of the aorta · Interrupted aortic arch · Overriding aorta · Aneurysm of sinus of Valsalva · Vascular ring Pulmonary artery Pulmonary atresia · Stenosis of pulmonary artery Subclavian artery Aberrant subclavian artery Great veins Superior/inferior vena cava Congenital stenosis of vena cava · Persistent left superior vena cava Pulmonary vein Anomalous pulmonary venous connection (Total, Partial) · Scimitar syndrome Arteriovenous malformation Cerebral arteriovenous malformation vascular navs: anat/physio/dev, noncongen/systemic vasculitis/congen/neoplasia, symptoms+signs/eponymous, proc