Web Producer: Brad Maglinger
Governor Frank O'Bannon arrived at Northwestern Memorial Hospital with severe bleeding in his head. At first, doctors thought he'd had a hemorrhagic stroke, where a weakened blood vessel ruptures. But after they ran some tests, there was a new diagnosis.
"He had both a non-hemorrhagic and hemorrhagic stroke," explains Northwestern neurosurgeon Dr. Wesley Yapor.
A non-hemorrhagic stroke is called an ischemic one. It happens in arteries that have been partially blocked by fatty plaque.
If the surface ruptures, the body responds as if the artery has been cut. A clot rapidly forms at the site, blocking the flow of blood to part of the brain.
"Sometimes what will happen is that clot or that area or that little fleck of cholesterol will get pushed downstream," says neurosurgeon Dr. Matthew Kern. "But if it's long enough that the brain and the blood vessels haven't had blood or oxygen for a long time, then they become very weakened and when there's a re-establishment of blood flood. The brain and the blood vessels can't handle it. It's like water being released from a dam, it can't handle the blood flow and the pressure and it actually just spills out into the brain."
The governor had what's called a hemorrhagic transformation of an ischemic stroke. It's reasonably common, but the prognosis for each patient is anything but.
Doctors say the swelling is going down in his brain, which is a good sign, but it's still to early to tell how much neurological function he'll regain.