Johnson: A Congenital Brain Tangle

CNN reports that Sen. Tim Johnson has been dignosed with a congenital arteriovenous malformation. (AVM).

CNN's Sanjay Gupta: "We're talking about a long road, here." Recovery time may take weeks or months or longer.

The Johnson family is said to be "encouraged and optimistic."

The location of the malformation -- near Broca's area, which helps to control speech, suggests that he will need significant therapy to recover his full speech functions.

If the capillary bed is thought of as a sponge, then an AVM is the rough equivalent of jamming a tangle of flexible soda straws from artery to vein through that sponge. On arteriorgram films AVM formation often resemble a tangle of spaghetti noodles. This tangle of blood vessels forms a relatively direct connection between high pressure arteries and low pressure veins.