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At a glance

Malformation characterized by cerebral anomalies and a median skull gap originating from the nasal root, orbits, or forehead (sincipital encephalocele), or the skull base or occiput (occipital encephalocele), allowing cerebrospinal fluid and/or brain to herniate. The encephalocele itself is defined as a herniation of part of the cranial contents through this skull defect. It may contain meninges (meningocele), meninges and brain (meningoencephalocele), or meninges, brain, and ventricle (meningoencephalocystocele).

Synonyms

Cephalocele; Craniocele; Cranial Meningoencephalocele; Cranium Bifidum.

History

The first description in the literature goes back to 1774 when M. Guyenot brought before the Academy of Surgery of Paris a man, 33 years old, who was born with a tumor on the left side of his forehead. This tumor measured 21 inches across, and pulsated. Around it could be felt a defect in the ossification of the frontal bone. The man’s intellects were unimpaired, but there was a deficiency of power of the right arm.

Definition

Defect of neural tube development resulting in an osseous defect in the midline of the skull that allows herniation of the meninges and portions of the brain.

Classification

Encephaloceles located in the upper portion of the face are generally classified as nasofrontal, nasoethmoidal, or nasoorbital. They can also appear along any part of the cranial vault during abnormal closure of the cranial sutures. The most common location for encephaloceles is located in the occipital region. Based on the content of the “sac,” the encephalocele is termed either meningocele (only cerebrospinal fluid present) or meningoencephalocele (brain tissue also present).

Incidence

The incidence is established at 1:5,000 to 10,000 live births in the general population worldwide. The Centers for Disease Control and Prevention (CDC) in the United States estimates that approximately 375 babies are born each year with an encephalocele. There is no sexual predilection reported; however, females tend to have more frequently an occipital encephalocele whereas males present predominantly with nasofrontal encephalocele. Occipital encephaloceles appear more common in Europe and North America whereas frontal encephaloceles are seen more frequently in Southeast Asia, Africa, Malaysia, and Russia. Ethnic, genetic, and environmental factors, as well as parental age, can all affect the likelihood of encephaloceles. The condition can occur in families with a family history of spina bifida.

Genetic inheritance

Multifactorial inheritance pattern. Although the exact cause is unknown, encephaloceles are caused by failure of the neural tube to close completely during fetal development. Research has indicated that teratogens, trypan blue (a stain used to color dead tissues or cells blue), and arsenic may damage the developing fetus and are associated with an increased incidence of encephaloceles. Finally, an association between an increase incidence of encephalocele has been reported in pregnant woman presenting with folic acid deficiency. ...

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