Ventriculomegaly is a condition in which the brain ventricles, or fluid-filled cavities, are enlarged due to build up of cerebrospinal fluid (CSF).

What is Ventriculomegaly?

Ventriculomegaly is a condition in which the brain ventricles, or fluid-filled cavities, are enlarged due to build up of cerebrospinal fluid (CSF). CSF is a fluid that protects the brain and spinal cord. The severity of ventriculomegaly depends on how enlarged the brain is. In some cases, fluid keeps building up, and the ventricles grow larger over time. This condition is known as hydrocephalus.

Ventriculomegaly is the most common fetal brain abnormality, occurring in up to 1.5 per 1,000 pregnancies.

What are the Symptoms Associated with Ventriculomegaly?

Ventriculomegaly is first found prenatally by the presence of enlarged ventricles (greater than 10 mm).

Newborns with mild ventriculomegaly may have no signs or symptoms. When children develop hydrocephalus, one or more of the following symptoms may occur:

  • a rapidly growing, large head
  • full or bulging “soft spot” at the top of the head
  • bulging veins in the scalp
  • irritability or sleepiness
  • poor feeding and/or projectile vomiting
  • abnormal eye movement, such as not looking upward or always looking downward
  • developmental delays

What Causes Ventriculomegaly?

Ventriculomegaly develops early in pregnancy. Two of the main factors that cause enlarged ventricles are:

  • An injury or problem with brain development around the ventricles
  • A blockage or imbalance in the ventricular system which prevents spinal fluid from moving or being absorbed normally

Ventriculomegaly usually occurs spontaneously. It can happen on its own or be associated with infection, genetic problems or other birth defects, such as spina bifida or heart defects.

How is Ventriculomegaly Diagnosed?

Ventriculomegaly is often diagnosed through prenatal ultrasound when the brain ventricles are measured. Sometimes a fetal MRI is also done to give more detailed images.

The condition may be found as early as 12 weeks of gestation. It can be monitored during pregnancy with repeated ultrasounds to look for slowly enlarging ventricles.

How is Does Ventriculomegaly Affect Delivery?

Babies diagnosed with ventriculomegaly should be delivered in a hospital that is prepared to treat babies with complex birth defects so they can have access to a team of specialists and a neonatal intensive care unit (NICU).

Pre-term or Cesarean deliveries are not needed unless there are other fetal or obstetrical problems, such as when the size of the head prevents a vaginal delivery. This situation would be considered highly unusual.

How is Ventriculomegaly Treated?

Mildly enlarged ventricles often need no treatment. Hydrocephalus can be treated soon after birth with a procedure that creates a pathway for extra fluid to drain out of the brain. This can be done by placing a ventriculoperitoneal shunt or performing a surgery to reduce spinal fluid and create a hole in the floor of one the ventricles to bypass the blockage.

The timing of the procedure depends on the symptoms and the child’s overall medical condition. Complications can include shunt infection or malfunction. These complications would require other surgeries.

What are the Long-term Effects of Ventriculomegaly?

Outcomes for babies with ventriculomegaly depend on both the cause of the ventriculomegaly and whether it is progressive or not. Most children with mild, nonprogressive cases that do not involve brain damage or developmental anomalies will not have any long-term health effects. More severe cases may need surgery. These children would be more likely to have neurological disabilities.