Hydranencephaly is a rare condition that happens during fetal development. The baby is often born with an enlarged head and some parts of the brain may be missing.
The disease affects about 1 in 50,000 births.
If your child has this condition, part of the front side of their brain will be missing and filled with cerebrospinal fluid. This buildup of fluid in their brain is called hydrocephalus and often causes increased pressure inside their head.
Hydranencephaly often leads to death.
What Causes Hydranencephaly?
Hydranencephaly has been linked to several possible causes, such as:
- A blockage in the baby’s carotid artery that prevented blood flow to the brain
- Infections in the womb that caused the baby’s brain tissue to die
- Lack of oxygen to the baby’s brain
- Genetic syndromes or gene mutations
- Exposure to toxins in the womb
- Twin-to-twin transfusion syndrome
- Fowler Syndrome, Trisomy 13, and other rare syndromes
While the exact cause of hydranencephaly is unknown, it affects both male and female babies at the same rate. Increased risk of developing hydranencephaly has also not been linked to any specific race or ethnicity.
How Is Hydranencephaly Diagnosed?
Early signs of hydranencephaly can sometimes be diagnosed during prenatal ultrasounds. Some babies do not show any signs of hydranencephaly until birth or even months afterward.
If your baby shows symptoms of the condition, doctors will use a combination of tests to make an accurate diagnosis. They will ask about your family history, and order imaging tests such as a CT scan or MRI to get a better look inside your baby’s brain. These tests let doctors see the parts of your baby’s brain that are undeveloped. Your doctor might also suggest having an amniocentesis to check for defects in the baby’s chromosomes and to help confirm diagnosis.
When Does Hydranencephaly Happen?
Hydranencephaly happens after the 12th week of pregnancy, while your baby’s brain is developing. The chances of miscarriage and stillbirth are higher for babies with hydranencephaly, but pregnancies can appear normal. You might feel regular fetal movements, and your uterus will expand and grow normally.
What Happens to a Baby with Hydranencephaly After Birth?
Sometimes babies with hydranencephaly have normal deliveries and don’t show any signs of hydranencephaly at birth. They might have average head sizes, reflexes, and muscle control but begin to have symptoms in the following weeks or months. Signs of hydranencephaly in infants include:
- Irritability and crying
- Increased muscle tone
- Enlarged head (hydrocephalus)
- Poor feeding
- Difficulty maintaining body temperature
- Seizures or muscle spasms
- Stiffness or paralysis
Children that live past infancy will face continued health challenges. These children will likely have poor vision or blindness, deafness, and impaired physical and mental development. They might also have chronic respiratory and gastrointestinal problems.
Is There Treatment for Hydranencephaly?
There is currently no treatment that can grow or develop your baby’s missing brain tissue.
Hydranencephaly treatments focus on managing your baby’s symptoms and improving their quality of life. It is likely your baby will need to have surgery to implant a shunt in their brain. A shunt is a hollow tube that will drain fluid and reduce pressure in your baby’s head.
Depending on their condition, your baby might also need other care and treatments to manage other symptoms.
What Is the Outlook for Babies Born with Hydranencephaly?
Most babies born with hydranencephaly will not survive more than one year, and those who survive past infancy will have shortened life expectancies. Their condition requires constant care and management during their lifetime.
How long a baby with hydranencephaly can survive depends on how much of their brain is working properly. The brain stem is responsible for controlling breathing and regulating body temperature. The more developed your baby's brain is, the greater chance they might have to live past infancy.
In recent years there have been cases of people with hydranencephaly having longer life expectancies. Some have lived 20 years or more. The longest living person with the condition died at age 33.