Cephalocele is a protrusion of intracranial contents through a bony defect of the skull. Most cephaloceles are midline and occipital extracranial masses. If only meninges protrude, it is called meningocele. Cephaloceles may be a part of several syndromes, especially Meckel syndrome (cephalocele, polycystic kidneys, and polydactyly) or trisomy 13, and are often associated with other malformations.
Incidence: 1-5 in 10,000 births, which varies with ethnic group and geographic region. Occipital cephaloceles are most common in the West, whereas anterior cephaloceles are much more common in Southeast Asia (1:5000 in Thailand compared with 1:35,000-40,000 in Europe).
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- Skull defect, usually in the occipital area (90% of cases), best visualized on the standard transcerebellar and transthalamic view.
- Skull defect of anterior cephalocele is more difficult to visualize and may present as extracranial mass with hypertelorism and the cephalocele may best be seen on the facial profile view.
- Skull defect in an asymmetric area is often related to amniotic band syndrome and other associated anomalies may be seen.
- Extracranial mass protruding through the defect
- meningocele, an entirely cystic mass
- a solid mass, often showing gyri and sulci (encephalocele)
- a solid cystic mass (meningoencephalocele).
- Microcephaly, commonly seen.
- Possibly ventriculomegaly.
- Polyhydramnios in some cases.
- The lemon-shaped appearance of the bony calvarium that occurs with open NTD and with the Arnold-Chiari type II malformation.
- Associated anomalies of specific syndrome, especially Meckel syndrome (cephalocele, polycystic kidneys, and polydactyly) , Waker-Warburg syndrome (cephalocele, ocular malformations, Dandy-Walker malformations), and Joubert syndrome.