Ventriculomegaly occurs when the fluid-filled structures (lateral ventricles) of the brain are too large.
The brain and spinal cord are covered in a clear protective liquid called cerebrospinal fluid (CSF). Spaces within the brain – called ventricles – are also filled with CSF. In a normal infant’s brain, the ventricles are about 10 millimeters wide. In a baby with ventriculomegaly, CSF becomes trapped in the ventricles and they expand, putting extra – potentially dangerous – pressure on the brain.
Ventriculomegaly is closely related to a condition called hydrocephalus, a problem that prevents CSF from circulating and being normally absorbed, which causes the fluid to build up in the ventricles progressively.
This condition usually occurs spontaneously, meaning that it doesn’t appear to be passed down in families.
There are four main causes of ventriculomegaly:
- Damage or loss of brain tissue
- Defects in brain development
- Imbalance in fluid circulation and absorption that becomes compensated
In most cases, infants with mild ventriculomegaly don’t exhibit any symptoms. If the condition is progressive, the baby may start to develop signs of hydrocephalus after birth.
Signs and symptoms of hydrocephalus include:
- Abnormally full fontanel
- Abnormally rapid head growth
- Developmental delays
- Distended scalp veins
- Eyes that cannot look upward or seem to be staring down
- Irritability or abnormal sleepiness
- Poor feeding