Senator Tim Johnson’s brain started to bleed because of an Arteriovenous Malformation (AVM), a condition shared by approximately 300,000 Americans, most of whom don’t know they have the condition. Only about one tenth of people with an AVM experience symptoms, which can include headaches, and even seizures.
About one in every fifty cases of hemorrhagic strokes is caused by an AVM. AVMs kill about 3,000 people each year in the USA.
Most people who have this condition will never know they have it as symptoms rarely appear. When they do, it means the AVM has grown. Internal bleeding can even happen without the patient being aware it. However, if the bleeding rate increases, consequences can be extremely serious.
In Johnson’s case a good many people witnessed his sudden inability to speak. He was taken to hospital where doctors eventually decided to intervene surgically – the excess blood had to be drained.
Experts say Johnson’s prognosis is not easy to predict. When he wakes up they will have a better idea. Tests can predict whether there is any long-term damage, but he needs to be awake for the tests to be done. His outlook depends on many factors, such as, how much bleeding there was, where it took place in the brain, and how successful the surgery was.
An AVM can be treated with surgery. It is easier to do when the area is not bleeding. Johnson’s surgeons would have had to work in an area that was bleeding. If the AVM is buried under lots of essential brain tissue, the task is much more difficult, as only way to get to it is to cut through.
What is an AVM, or Arterio-Venous Malformation?
Put simply, an AVM is a tangle of tiny veins which makes it more difficult for blood from the arteries to eventually make their way to the veins. Oxygen-rich blood goes down your arteries from your heart and lungs, they channel off into smaller branches, those branches have even smaller branches, this goes on till the blood passes through tiny capillaries – their aim is to nourish tissue. When the oxygen is taken out of the blood, it needs to make its way back to your heart, through tiny vein capillaries, into larger veins and back to your heart and lungs.
A tangle of tiny veins which block this process is called an AVM. Imagine a ball of yarn with many knots, with threads coming out of it in several directions. As you pull at the threads, the center of the yarn gradually tightens. The tangle of veins will tighten in the same way the center of the yarn does, if blood finds it harder to get through the vessels and they start to swell. Eventually, you have a tight ball in the center, the blood cannot get through, so it starts to seep out of the blood vessels (bleeding). Doctors call this tight ball in the center the ‘nidus’.
Surgery can close off the arteries that bring blood to the nidus.
AVMs can be present in the brain, lung, kidney, spine, liver and spleen.
The risk of bleeding from an AVM grows with age:
— Risk for a 10 year old – 33.5%
— Risk for a 20 year old – 55.8%
— Risk for a 30 year old – 70.6%
— Risk for a 40 year old – 80.3%
— Risk for a 50 year old – 86.8%
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— AVM Support (United Kingdom)
— AVM Support (Massachusetts General Hospital)
— AVM Survivors Community
Written by: Christian Nordqvist
Editor: Medical News Today