encefalocele

Encephalocele (also spelled encefalocele) is a rare congenital neural tube defect in which brain tissue and meninges protrude through a defect in the skull, forming a sac outside the cranial cavity. The protruding sac may contain varying amounts of neural tissue and cerebrospinal fluid. The most common location is the occipital region, but frontal and other forms occur depending on region.

Pathogenesis involves failure of neural tube closure during early embryogenesis, usually weeks 4–6 of gestation. Risk factors include maternal folate deficiency, diabetes, obesity, certain medications, infections, and a family history of neural tube defects. Periconceptional folic acid reduces risk for neural tube defects in general.

Newborns present with a soft swelling at the skull. The sac is often covered by skin; contents range from meninges alone to brain tissue. Associated anomalies such as hydrocephalus, microcephaly, or other congenital defects are common and influence prognosis. Seizures or developmental delays may occur later in life.

Prenatal diagnosis is usually made by ultrasound and can be refined with fetal MRI. After birth, CT or MRI defines the skull defect and the sac contents.

Management requires a multidisciplinary team. Postnatal surgical repair aims to reduce herniated tissue and close the skull defect, with timing individualized. Many patients require treatment for hydrocephalus or other anomalies. Prognosis varies widely and depends on brain tissue involved and associated defects; small sacs with little brain tissue have better outcomes.

Epidemiology varies by region; encephalocele remains a rare condition within neural tube defects, with occipital forms more frequent in many populations and frontal forms more common in others.