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Arteriovenous malformation refers to an abnormal connection between arteries and veins, bypassing the capillary system.
AVMs can appear in any location.
The estimated detection rate of AVM in the US general population is 1.4/100,000 per year.
Although AVMs are often associated with the brain and spinal cord, they can develop in any part of the body.
Many AVMs are asymptomatic.
They can cause intense pain or bleeding or lead to other serious medical problems.
AVMs are usually congenital.
There are known genetic mutations, such as tumor suppressor PTEN gene which can lead to an increased occurrence throughout the body.
AVMs are debilitating conditions caused by either inherited or somatic genetic mutations.
KRAS gain of function mutations are frequently seen in sporadic malformations, particularly those involving the brain.
RAS proteins act as molecular switches that regulate cellular proliferation, growth, and migration.
Symptoms vary according to the location of the malformation.
Approximately 88% of individuals with an AVM are asymptomatic.
Symptoms of a cerebral AVM include headaches and seizures, with more specific symptoms occurring that normally depend on the location of the malformation and the individual.
An estimated 300,000 Americans have AVMs, and 12% exhibit symptoms.
Neurological manifestations of brain AVMs include: impaired coordination, muscle weakness, paralysis, dizziness, dysarthria, aphasia, apraxia, numbness, tingling, pain, memory and thought-related problems, such as confusion, dementia or hallucinations.
A brain AV expansion or a micro-bleed can cause epilepsy, neurological deficit, or pain.
Cerebral AVMs may present with:
Bleeding in 45% of cases.
Acute onset of severe headache, and usually the worst ever.
Bleeding may be associated with a new neurologic deficit.
Seizures
In an unruptured brain AVM, the risk of spontaneous bleeding is as low as 1% per year.
After a first rupture, the annual bleeding risk may increase to more than 5%.
Presence and nature of neurologic deficits depend on location of lesion and the draining veins.
Pulmonary arteriovenous malformations have no symptoms in up to 29% of cases.
AVMs lacks the dampening effect of capillaries on the blood flow, so they can get progressively larger over time as the amount of blood flowing through it increases, forcing the heart to work harder to keep up with the extra blood flow.
AVMs can be extremely fragile and are prone to bleeding because of the abnormally direct connections between high-pressure arteries and low-pressure veins.
Areas of tissue surrounding an AVM can be deprived of capillary function, removal of CO2 and delivery of nutrients to the cells.
Pathophysiologically, a tangle of blood vessels can be created that has no capillaries. The resultant sign, audible
Using a stethoscope, a rhythmic, whooshing sound caused by excessively rapid blood flow through the arteries and veins can be heard, and is ref2242ed to as a bruit.
AVMs May be diagnosed by Computerized tomography (CT) scans, CT angiography, or Magnetic resonance imaging (MRI) scans.
AVMs have been identified in various parts of the body:
brain
spleen
lung
kidney
spinal cord
liver
intercostal space
iris
spermatic cord
extremities
intestine
AVMs may occur in isolation or as a part of another disease process such as Von Hippel-Lindau disease or hereditary hemorrhagic telangiectasia.
They can be associated with associated with aortic stenosis.
Bleeding from an AVM can be relatively minimal or devastating.
Can cause severe and fatal strokes.
Brain AVMs can be symptomatic with seizures, headaches, and focal neurologic deficits.
Brain AVM-specific treatment may also involve endovascular embolization, neurosurgery or radiosurgery.
Embolization, can be achieved by cutting off the blood supply to the AVM with coils, particles, acrylates, or polymers introduced by a radiographically guided catheter.
Targeting KRAS G12C may be useful to treat vascular malformations (Sotorasib).