Treating Hydrocephalus

Hydrocephalus is a condition that occurs when too much cerebrospinal fluid (CSF) builds up in the brain. Cerebrospinal fluid is a clear, colorless fluid that surrounds and cushions the brain and spinal cord, providing essential nutrients and removing waste products.

Hydrocephalus Symptoms

Hydrocephalus is quite common in medulloblastoma and is usually a main cause of symptoms that lead to a diagnosis. The buildup of fluid from the blockage by the tumor is what causes many of the common symptoms of medulloblastoma such as headaches, vomiting, and vision and balance issues.

Treatments for Hydrocephalus in Medulloblastoma

Often once a tumor and hydrocephalus are found on MRI, the patient will have a temporary external ventricular drain (EVD) placed to quickly relieve pressure on the brain. If the hydrocephalus is severe enough or cannot resolve on its own, a permanent ventriculoperitoneal shunt (VP shunt) is surgically placed or an endoscopic third ventriculostomy (ETV) procedure might be attempted. Below are more details on each of these approaches.

None of these are cures for hydrocephalus, but rather treatments. Once the tumor is removed, then hydrocephalus often resolves.

External Ventricular Drain (EVD)

An external ventricular drain (EVD) may first be used in treating hydrocephalus to help remove excess CSF. An EVD is a temporary device placed during a surgery.

During the surgery, a tube is inserted into the ventricle of the brain, which is a fluid-filled cavity deep within the brain. The tube is then routed out of the body and connected to a drainage system. The extra CSF will drain out of the body to this system.

The EVD will be removed as soon as the care team determines it’s safe to take it out.

Ventriculoperitoneal Shunt (VP Shunt)

The most common and well-established method to treat hydrocephalus is with a ventriculoperitoneal shunt (VP shunt). A neurosurgeon will place the VP shunt during a surgery.

During the surgery, a tube is placed from the outer surface of the head through the skull and brain into a lateral ventricle, which is a fluid-filled cavity deep within the brain. The shunt is connected to a device called a valve, which helps regulate how much fluid leaves the brain. The valve also makes sure CSF only flows out of the ventricle and not back in.

The valve sits under the skin and connects to a tube that leads to a place in the body where the CSF can be absorbed back into the bloodstream (where it would have gone from the brain directly, if it could).

The most common end point of shunts is the peritoneal cavity, or the belly. But shunts may also go to the chest, through blood vessels to the heart, or even to the gallbladder.

VP shunts can be either fixed or programmable. In fixed shunts, the valve drains a defined amount and that setting cannot be changed. If a change is needed in how much fluid the valve allows to drain, a new valve will need to be put in. In programmable shunts, also called adjustable shunts, the valve setting can be adjusted to allow different drainage levels.

Shunts can have complications. They are foreign to the body, so the body may react to them and block off their flow. They are also mechanical systems that can break or malfunction. The most common way they become a problem is when they become infected, which occurs in about 5–14% of cases. (Neurosurgeons are very focused on how to reduce the rate of these infections.) When a shunt is infected, it has to be removed, and—after a period of time—replaced with a clean system.

Effective shunts have been around for about 50 years, and they save and improve the lives of tens of thousands of kids each year.

Endoscopic Third Ventriculostomy (ETV)

Another way to drain fluid from the ventricles is with an endoscopic third ventriculostomy (ETV). This procedure creates an alternative pathway from the third or fourth ventricle of the brain when the normal pathway is blocked. “Third ventriculostomy” refers to the area of the brain where the pathway is created.

In this procedure, a small opening is created in the third ventricle of the brain, which is a fluid-filled cavity deep within the brain. This is done to allow the cerebrospinal fluid to move naturally out of the blocked area. There is no tubing placed in the body in an ETV as there is with the VP shunt explained above.

Whether an ETV is an option depends on the anatomy of the patient, which your care team will assess. One goal of an ETV is to avoid the need for a shunt. However, if the hole in the third ventricle created by the ETV closes up, a shunt might then be needed.