Topic Overview

What is congenital hydrocephalus?

Congenital hydrocephalus is a buildup of excess cerebrospinal fluid (CSF) in the brain at birth. The extra fluid can increase pressure in the baby's brain, causing brain damage and mental and physical problems. Finding the condition early and treating it quickly can help limit any long-term problems. But long-term effects mostly depend on what caused the fluid buildup, how bad it gets, and how the baby responds to treatment.

This condition is rare. About 1 out of every 1,000 babies is born with it.¹ This means that about 999 babies out of 1,000 are not born with it. When hydrocephalus doesn't occur until later in life, it is called acquired hydrocephalus. This topic focuses on hydrocephalus that is present at birth (congenital).

What causes congenital hydrocephalus?

This condition is caused by an imbalance between how much CSF the brain makes and how well the body is able to process it.

Normally, CSF flows through and out of chambers of the brain called ventricles, and then around the brain and spinal cord. The fluid is then absorbed by the thin tissue around the brain and spinal cord. But with hydrocephalus, the fluid can't move where it needs to or is not absorbed as it should be. And in rare cases, the brain makes too much fluid.

Congenital hydrocephalus may happen because of:

• Bleeding in the fetus before birth.
• Certain infections in the mother, such as toxoplasmosis or syphilis.
• Other birth defects, like spina bifida.

What are the symptoms?

The clearest symptom of hydrocephalus is a head that is larger than normal. You and your doctor may notice it at birth or within the first several months after your baby is born. But keep in mind that babies' heads grow a lot during the first year. It is only when the head size grows faster than the normal rate for a baby's height and weight that your doctor may think that there is a problem.

The condition may cause the soft spot (fontanelle) on your baby’s head to feel firm or bulge out. If pressure builds in the brain, your baby may:

• Be irritable.
• Sleep too much.
• Vomit.
• Eat very little.

How is congenital hydrocephalus diagnosed?

Your doctor may suspect that your baby has congenital hydrocephalus if your baby’s head is larger than normal. Your doctor can check for the problem during a physical exam soon after birth.