Encephalocele

Overview

An encephalocele is a rare birth defect in which part of the brain and its protective membranes bulge out through an opening in the skull. It is a type of neural tube defect, meaning it arises from a problem with the early development of the structures that form the brain, spinal cord, and skull during the first weeks of pregnancy.

The protrusion is usually covered by skin or membrane and can occur at the back of the skull, near the forehead and nose, or elsewhere. The size and location vary widely, and these factors strongly influence the outlook. Some encephaloceles are small and contain little brain tissue, while others are larger. Treatment is primarily surgical, and outcomes depend on how much brain tissue is involved and whether other problems are present.

Symptoms

The most obvious feature is a visible sac on the head, though some encephaloceles are hidden inside the nose or skull base. Associated features can include:

• A sac-like bulge on the back of the head, the forehead, or near the nose
• A small amount of fluid or, in some cases, nasal drainage if the defect involves the skull base
• Neurological problems that vary with the amount of brain tissue involved, such as developmental delay
• Build-up of fluid in the brain (hydrocephalus)
• Seizures, poor coordination, or vision problems in some children
• Distinctive facial features when the defect is near the front of the skull

Many of these features are detected and assessed by specialists soon after birth, or even before birth on ultrasound.

Causes

Encephalocele results from incomplete closure of the neural tube and skull during early fetal development. The exact cause is often not known, but contributing factors include:

• Neural tube development problems: The neural tube normally closes within the first month of pregnancy; failure to close fully can lead to this defect.
• Genetic factors: Some cases occur as part of genetic syndromes.
• Environmental and nutritional factors: Inadequate folic acid (folate) in early pregnancy is linked to neural tube defects in general.

In many cases a single clear cause cannot be identified, and the condition is thought to result from a combination of genetic and environmental influences.

Risk Factors

• A family history of neural tube defects
• Low folic acid intake before and during early pregnancy
• Certain genetic conditions or syndromes
• Some maternal health conditions and medications that affect folate
• A previous pregnancy affected by a neural tube defect

Diagnosis

Encephalocele is often identified before or shortly after birth:

• Prenatal ultrasound: Can detect the defect during pregnancy.
• Prenatal MRI: May provide more detail about the brain tissue involved.
• Examination at birth: A visible sac prompts immediate evaluation.
• Imaging after birth: CT or MRI scans define the size of the opening, the amount of brain tissue involved, and any associated abnormalities.

Genetic testing may be offered to look for associated syndromes, and a team of specialists evaluates the child to plan care.

Treatment

Treatment is usually surgical and tailored to the individual child:

• Surgery: The protruding tissue is repositioned when possible, the sac is removed, and the opening in the skull is repaired.
• Managing hydrocephalus: If fluid builds up in the brain, a shunt may be placed to drain it.
• Supportive and developmental care: Therapies for movement, speech, and learning, and treatment of seizures or vision problems as needed.
• Multidisciplinary follow-up: Ongoing care from neurosurgery, neurology, and other specialists.

The timing of surgery and the long-term outlook depend on the location and size of the encephalocele and how much functional brain tissue is involved. Care is individualized for each child.

Prevention

Not all cases can be prevented, but the risk of neural tube defects in general can be reduced:

• Take folic acid before conception and during early pregnancy, as recommended by a doctor
• Eat a balanced diet, including folate-rich foods
• Discuss any family history of neural tube defects with a healthcare provider before pregnancy
• Manage existing health conditions and review medications with a doctor when planning pregnancy
• Attend recommended prenatal care and screening

When to See a Doctor

Encephalocele is typically identified by medical teams before or at birth, and care is coordinated by specialists. For a child with a known or suspected encephalocele, seek prompt medical attention if there are signs such as:

• Increasing head size, bulging of the soft spot, or persistent vomiting (possible hydrocephalus)
• Seizures
• Leakage of clear fluid from the nose, which can occur with skull-base defects
• Fever with irritability or a stiff neck, which could indicate infection such as meningitis

Anyone planning a pregnancy should talk with a doctor about folic acid and, if there is a family history of neural tube defects, genetic counseling.

Related Topics

Frequently Asked Questions

References

1. Centers for Disease Control and Prevention (CDC). Facts about Encephalocele.
2. National Institute of Neurological Disorders and Stroke (NINDS).
3. MedlinePlus, U.S. National Library of Medicine. Encephalocele.
4. Genetic and Rare Diseases Information Center (GARD).