The network of vessels that transport blood to your brain looks like two trees. The trunks are the carotid arteries, which run up through the neck and branch into the brain, getting smaller and smaller as they ascend. Sometimes, those branches develop a dangerous malformation called an aneurysm. It happens when the artery wall weakens and begins to bulge. An aneurysm often looks like a berry hanging from a branch. About one in 50 Americans will develop an aneurysm in their lifetime. The lucky ones will never know it. But in some patients, the aneurysm bursts like a balloon, and blood pours into the brain, damaging tissue, in an event commonly called a hemorrhagic stroke. Neurosurgeon Dr. Adi Iyer, knows his way around the branching arteries that feed our brains. He treats a variety of diseases there. When a hemorrhagic stroke patient comes into the hospital, he treats the ruptured artery as fast as he can because time lost is brain lost. Listen to this episode to learn how Dr. Iyer does it, and how he he can treat aneurysms before they burst.