Ventriculomegaly is a condition that affects the fluid-filled spaces in the brain. In this handout, you will learn about ventriculomegaly.

What is Ventriculomegaly?

Ventriculomegaly is a condition in which the ventricles (fluid-filled spaces in the brain) are larger than usual.

The brain has 4 ventricles – 2 at the top (on the left and right sides of the brain), one just below these two and one below the third one, near the top of the spine. Usually the problem is with one or both of the top ventricles.

What Causes Ventriculomegaly?

Ventriculomegaly is sometimes caused by too much fluid in the brain. Other times, the ventricles look big because the surrounding brain is too small. There are several conditions that can cause this, but most of the time the cause is unknown.

What are the Different Types of Ventriculomegaly?

A typical ventricle should measure fewer than 10 millimeters (mm), or a little smaller than a Cheerio®.

The different types of ventriculomegaly include:

  • Mild ventriculomegaly. This is when the ventricles are 11-12 mm. (About width of a Cheerio®.)
  • Moderate ventriculomegaly. This is when the ventricles are 13-15 mm. (A little wider than a Cheerio®.)
  • Severe ventriculomegaly. This is when the ventricles are larger than 15 mm. (About the size of a hazelnut or larger.)

How Do Doctors Diagnose Ventriculomegaly?

Doctors diagnose ventriculomegaly with an ultrasound or a fetal MRI (imaging of your baby’s brain and body). MRI can show more details than ultrasound. Most doctors recommend a fetal MRI to help determine why the ventricles are enlarged.

Will the Ventricles Shrink Down to Normal Size?

  • In about 3 out of 10 babies, the ventricles will decrease closer to normal size.
  • In about 6 out of 10 babies, the ventricles will stay the same size.
  • In about 1 out of 10 babies, the ventricles will continue to increase in size.

Who is on My Baby's Care Team?

Your baby will be followed by many different doctors, including:

  • Primary care pediatrician
  • Neurologist (doctor who specializes in the nervous system and brain), who will see your baby after delivery and may request more imaging after birth to assess the ventricles.
  • Geneticist (doctor who specializes in genetic conditions), who can help diagnose any genetic conditions that may have caused the ventricles to become enlarged.

What is the Outcome for My Baby and Possible Challenges They Might Face?

The outcome for babies with ventriculomegaly depends on the size and underlying cause of the enlarged ventricles. There are many outcomes, ranging from normal to more significant neurologic problems. Your doctor will talk to you more about what to expect after the fetal MRI. No matter what the outcome, the care team will be with you every step of the way.

Rev. 7/2019. Mass General for Children and Massachusetts General Hospital do not endorse any of the brands listed on this handout. This handout is intended to provide health information so that you can be better informed. It is not a substitute for medical advice and should not be used to treatment of any medical conditions.