Brain Aneurysm – After Effects

Q&A with Dr. Michael Chen

For those who survive a brain aneurysm, one of the most prevalent questions survivors and their loved ones have are…. What just occurred to my brain?

For starters, what happens if you actually survive a brain aneurysm?
It is hard to know definitively how people will do after they survive a brain aneurysm rupture. I’ve seen patients do amazingly well and, eventually, are essentially back to normal. I’ve seen others who need to stay in nursing homes and cannot take care of their own daily bodily functions. There are several factors that determine the severity of brain injury after a ruptured brain aneurysm. Because so many of them are uncontrollable, prevention is extremely important.

What goes on in your head after a brain aneurysm?
Brain aneurysms are a problem with the arteries, which transmit blood under pressure, pumped by the heart. Veins, on the other hand, transmit blood under very low pressure after it passes through your tissues or organs. When an aneurysm ruptures, blood enters, under considerable pressure, into the spinal fluid space that normally surrounds your brain. Any increase in volume within the skull (blood, in this case), quickly increases the pressure within the skull.

This mechanical pressure can damage the brain by having a squeezing effect, otherwise referred to as mass effect. In more severe situations, part of the brain may herniate into a space where it shouldn’t be in.

How severe is the damage from this mass effect?
The initial severity of this mass effect is an important determinant of how much neurologic injury results. Blood enters, under pressure, into the spinal fluid space (subarachnoid space) that normally surrounds the brain.

This spinal fluid space space is enveloped by a tissue layer called the arachnoid membrane. About a soda can’s worth of spinal fluid is formed each day (a very slow rate) and gets reabsorbed into the veins at certain locations. Depending on how much blood enters this space from the ruptured aneurysm, spinal fluid may not be able to drain normally. As a result, spinal fluid builds up, further increasing the pressure within the skull.

This is called hydrocephalus, and may factor into why a drain or shunt is needed to provide an alternative drainage route for the spinal fluid that continues to be produced by your body. Hydrocephalus can contribute to disabilities experienced post.

How does an aneurysm compromise blood flow to the brain?
The major blood vessels at the base of the brain which are suspended within the spinal fluid space have little supporting tissue surrounding it. When an aneurysm ruptures, blood surrounds the surface of these blood vessels. This blood settles and coagulates, then the body tries to clear it. As the blood is “digested” by the white blood cells, some of the by­products may irritate the normal surrounding tissues, including the arteries in the brain.

The normal muscle layer that makes up the wall of the artery may become irritated by this blood and contract, narrowing the vessel and compromising blood flow to the brain. This process is called cerebral vasospasm. This may lead to ischemic strokes or brain injury. There are several other processes that can occur, including seizures, infections, blood clots in the legs and heart problems.

Based on all of this, what is one of the most important questions to ask your doctor after surviving a ruptured brain aneurysm?  
Be sure to ask your physician to explain what went on during your aneurysm rupture. Your physician should take the time to explain what aneurysms are, what normal anatomy should be like, why one should be concerned about brain aneurysms and what the expectations going forward might be.