Hydrocephalus and Shunts - How do they work?

Although Cameron has had a shunt for 4 years, we’ve never really taken the time to truly explain how it works. In light of the last two weeks, I thought this post would be helpful for those who really want to understand what the heck is going on in Cameron’s brain. The picture above of the brain illustrates the ventricular system. The flow of fluid is essentially from top to bottom. In Cameron’s case prior to his birth, the Lateral ventricles were increased in size from typical ventricles. This buildup in pressure is called Hydrocephalus.

After his birth at 32 weeks, an Endoscopic Third Ventriculostomy was done, this was in an effort to avoid the shunt (a man made device). 2 months post ETV Cameron’s Ventricles were continuing to increase in size, so he went in for another surgery to have the shunt placed, this worked to keep his ventricles at an acceptable size.

The problem with a shunt is it's a man made device and can malfunction. Some children have many, many revisions. We have been lucky to only be on our 2nd revision. When the shunt isn't working, many things can happen:
1) The pressure builds, enlarging his ventricles and pushing his brain against his skull.
2) Slit Ventricles – where the ventricles decrease in size significantly, that they become slit like and there is not enough fluid in the ventricles (what it looked like on our MRI prior to surgery 9/2/10
3)The tubing for the shunt can snap, or the child can grow that the tubing is too short

All of these things can lead to a shunt malfunction causes irritability and vomiting among other things.


This picture shows how a shunt is placed to go into the ventricle and allow fluid to drain out the top, down a tube which is placed just under the skin and drain into the belly. The pink device on the top of the shunt is a valve to allow fluid to drain, but not allow fluid into the brain. The green stick like thing going into the brain is called the Catheter. In Cameron’s case, during his recent surgery they placed a new Catheter and moved the Valve around a bit. The shunt still connects to the same tube his old shunt used to then drain down into his belly.

One week post op when Cameron presented with lethargy and high fever, a shunt infection was suspected. The highest risk for infection is in the 6 months following a revision. If there is an infection they have to take out the entire shunt, and the patient is on an external drain for 7- 10days. I hope we never experience this.

The MRI on 9/10 showed his lateral ventricles has increased in size remarkably from the scan done prior to surgery, so all the alarm bells went off for the nurses, radiologists, residents and so forth telling us he would need another revision. But as we know his Nuerosurgeon liked the size of the ventricles compared to the pre surgery MRI where they almost seemed to no longer exist.

If after only one week there was such a dramatic change it certainly makes one wonder what they look like now, we’ll find out 10/5 when we go for another MRI.

We have been CVS episode free since the surgery, so there is hope that this shunt revision was the fix we needed. For now he continues on the Propranonol. Only time will tell…

I hope this helps better explain how shunts work.