An arteriovenous malformation is a rare defect of the circulatory system that develops prior to birth or soon thereafter. Blood flows from an artery directly into a vein through a passage known as a fistula, depriving the surrounding tissue of oxygen. Although it can occur anywhere in the body, it can have serious consequences when it occurs in the brain or spinal cord, where besides reducing the amount of oxygen delivered to the brain, it may press on nerves or cause hemorrhaging.
The most common symptom of an AVM is headaches. Other symptoms include hemorrhaging (bleeding), seizures and neurological problems such as paralysis, muscle weakness or loss of speech, vision, coordination or memory. Only about 12 percent of people with AVMs have symptoms. Symptoms are most often noticed in a person’s twenties, thirties or forties.
Not all arteriovenous malformations need treatment or can be treated. Neurosurgeons may use conventional surgery to remove the fistula. If possible, a less invasive approach using endovascular embolism will be used to plug the fistula using fast-drying biologically inert glues, fibered titanium coils, and tiny balloons. Lastly, radiosurgery will direct a high dose of radiation to damage the blood vessels in the fistula, which will degenerate and close off the lesion.
Cavernous malformations are a specific type of AVM made of clusters of abnormal, tiny blood vessels, and larger, stretched-out, thin-walled blood vessels filled with blood in the brain. They are also referred to as cavernomas, cavernous angiomas, cavernous hemangiomas or intracranial vascular malformations. Some forms are congenital. Not all cavernomas need treatment, but all require regular monitoring.
Symptoms depend on whether the cavernoma hemorrhages and its location in the brain. A patient may experience seizures, headaches, memory and attention problems, weakness in arms or legs, vision problems and balance problems. However, many people with cavernomas are asymptomatic and the lesions are discovered by chance.
Symptomatic cavernomas can be treated through medication alone. Surgery is recommended if a patient experiences one neurologically symptomatic hemorrhage from a lesion in an easily accessible area of the brain, where there is a low risk of interference with neurological function.