What is the outlook for hydranencephaly?

Table of Contents

  1. Symptoms
  2. Causes
  3. Diagnosis
  4. Complications
  5. Treatment
  6. Prognosis







Hydranencephaly is a rare disability present at birth that causes a central nervous system disorder. When it occurs, the front hemispheres or cerebrum of a baby’s brain are missing. In their place, the cerebrospinal fluid that typically cushions the brain fills the space.

The condition affects both male and female babies at equal rates. Some babies may be at higher risk of developing it if either of the parents carries genes that are suspected of causing the disorder.

While some scientists suspect genetics may play a role in hydranencephaly, the exact cause is unknown, and there is no cure for the condition. Often, a baby with hydranencephaly will die in the womb or within a few months of birth.

Fast facts on hydranencephaly:

According to the Brayden Alexander Global Foundation for Hydranencephaly, only 1 in every 250,000 newborns in the United States has hydranencephaly.

Worldwide, the rate of occurrence of the condition is 1 in every 10,000.

Newborns that survive may have vision problems, growth impairment, or intellectual disabilities.


Hydranencephaly in baby's head highlighted by sunlight, held in woman's arms.Hydranecephaly is a condition where parts of the front of the brain are missing at birth.

When a baby is born with hydranencephaly, there may or may not be obvious symptoms that the baby has the disorder. In clear cases, the baby’s head appears enlarged.

When the head is not enlarged, it may take weeks or even months for symptoms to be observed and suspected. Often, a baby may have limited or jerky movement.

Other symptoms of hydranencephaly can include:

failure to grow at a normal rate


vision difficulties

exaggerated muscle reflexes

increased muscle tone

intellectual disability

poor body temperature regulation

breathing and digestive problems


Some scientists suspect that hydranencephaly is a disorder inherited from a child’s parents.

Others suspect hydranencephaly occurs due to a blockage of the carotid artery where it enters the head. It is unclear, however, how or why a blockage may occur.

Another theory is that the baby’s central nervous system sustains an injury at a very early stage of development, or does not develop properly.

A few additional causes may include:

a mother’s exposure to poisonous substances

circulatory problems within the fetus

infection of the uterus at an early stage of development

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Ultrasound scan being performed on pregnant woman, baby image on laptop.Hydranencephaly may be diagnosed during a routine ultrasound scan.

Doctors may diagnose hydranencephaly at different points in time for different babies.

In some cases, detection can occur while the baby is still in the womb. An ultrasound scan may reveal that there are physical abnormalities of the fetus that suggest hydranencephaly.

In other cases, a doctor may see characteristic signs of the disorder at birth. However, it may not be until other signs and symptoms appear that a doctor will know more clearly to check for the disorder.

To make a diagnosis, a doctor may:

conduct a clinical evaluation

review the newborn’s medical history

identify physical characteristics

order a computerized tomography (CT) scan

request an X-ray that uses dye to highlight blood vessels

order a transillumination

A transillumination is a relatively simple, painless procedure. Doctors place a bright light at the base of the baby’s head, which allows them to see if the brain has grown irregularly.

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