Encephaloceles

Abstract

Congenital encephalocele, a type of neural tube defect, is a herniation of the brain and meninges through a cranial defect. No causal relationship has been established. However, prevalence of certain subtypes is more common in relation to ethnicity. Whilst patients of North American and Western European decent are likely to develop occipital encephalocele, patients from Southeast Asia, parts of Russia, and central Africa mostly developed sincipital encephaloceles. Classification is based on anatomical location of the internal bony defect and further sub-classified with respect to the external defect created by the protruding sac. The aperture through which the encephalocele emerges is generally situated along a suture, intersection of several bones or junction of ossification centres. The breadth of subtypes, locations, severity and associated anomalies produces a large spectrum of signs and symptoms. However, urgent treatment is indicated with breaches of the overlying skin, CSF leak from the sac, infection and/or meningitis The diagnosis is, in most cases, made antenatally or clinically at birth. However, some may be occult, as in many basal encephaloceles, and present with complications. Combined CT and MRI is ideal for assessment of cranial defect and soft tissue architecture. Transcranial (open) approach is the most common method to repair the frontal and basal defects, however, advances have been made with transnasal (Endoscopic) surgery with reduced side effects. As for occipital encephalocele, most cases are not severe and are corrected with simple sac excision and dural closure.