MADELEINE BRAND, host:
So what is arteriovenous malformation? AVM, as it's known, is an abnormal connection between the arteries and veins. It can occur anywhere in the body, but when it happens in the brain, it can have widespread and serious effects.
Remember Nate from the TV show "Six Feet Under"? That's what he had.
(Soundbite of TV show, "Six Feet Under")
Unidentified Man (Actor): (As Doctor) Yup. It definitely looks like AVM.
Mr. PETER KRAUSE (Actor): (As Nate) If I'd never been in a car, I shouldn't have gotten a routine x-ray on my skull, this would have never even come up, right?
Unidentified Man: (As Doctor) Until something happened.
BRAND: Here to tell us more about AVM is Dr. John Marler of the National Institutes of Health. Welcome to the program.
Dr. JOHN MARLOR (National Institutes of Health): Thank you.
BRAND: I understand that AVM is created before birth in utero or shortly after and Senator Tim Johnson just suffered symptoms. He's 59 years old. So that suggests that someone with this condition can live a long time without symptoms, so -
Dr. MARLER: Live your whole life.
BRAND: Your whole life. How common is it?
Dr. MARLER: It's not that common. It probably affects at most a few percentages of people. It's really hard to determine because people can live their whole lives with an AVM and never make it into anybody's medical record.
BRAND: Do doctors know what causes the blood vessels to develop abnormally in utero?
Dr. MARLER: No, we don't. AVMs when we discover them are all shapes and sizes. They often are discovered incidentally as in Nate doing an x-ray or a brain scan for another reason. Sometimes they present with a seizure and occasionally with bleeding. When they present with bleeding, it's usually - I won't say minor - but it's not the serious kind of bleeding that is often fatal that occurs with the bleeding that comes from high blood pressure, another cause of the bleeding.
BRAND: And it appears in Senator Johnson's case that he did present with symptoms. He had slurred speech. And NPR has information that the location of the AVM is in the part of his brain that influences speech and movement, so if that turns out to be true, is that a more serious form of AVM?
Dr. MARLER: It's hard to tell at this time a specific case from the information. Usually, the bleeding from an AVM goes into the cavities of the brain and doesn't destroy the tissue of the brain. It's that that we're concerned about, is how well the brain survives this bleeding. Later, decisions can be made about whether to totally remove the AVM or to just let it take its natural course.
BRAND: And would the patient have to then undergo some sort of rehab?
Dr. MARLER: It depends on the deficit that's left if there's any disability at all. I mean, at this point, it wouldn't be unusual to have a very good recovery so that rehab wouldn't even be required. It depends entirely on the individual case.
As I say usually the hemorrhage from AVM is not as serious as other brain hemorrhages that might lead people to have a lot of concern.
BRAND: Dr. John Marler of the National Institutes of Health. Thank you very much.
Dr. MARLER: All right.
BRAND: And for more information about Senator Johnson's illness, go to our Web site, NPR.org. Transcript provided by NPR, Copyright NPR.