SINCIPITAL ENCEPHALOCELE

Discussion

Sincipital encephalocele is a uncommon congenital midline nasal mass.Although uncommon this disorder is clinically important because of their potential for connection to CNS. Sincipital encephalocele refers to a protrusion of cranial contents through foramen caecum placed anteriorly with respect to the cribriform plate. [1]

Sincipital encephalocele is subclassified into three forms: (1)Nasofrontal:the defect lies in the bregmatic region between the frontal and nasal bones. The ostium is at the nasion between the orbits producing hypertelorism; (2)Nasoethmoidal: The osseous defect lies in the cribriform plate of the ethmoid bone where brain tissue herniates into the nasal cavity;and (3) Nasoorbital: The osseous defect lies between the frontal process of the maxilla and the ethmoid bone. The encephalocele passes into the medial wall of the orbit and presents as an orbital mass. [2],[3]

Sincipital encephalocele may present as nasal broadening and / or as a blue, pulsatile, compressible mass near the nasal bridge which transilluminates, with crying or with bilateral compression of the internal jugular veins (positive furstenberg test) or as an intranasal mass arising from the cribriform plate. [1]

IMAGING STUDIES (CT/MRI):- Plain films to examine C- spine and cranio-vertebral junction followed by CT/MRI. Ultrasound may reveal contents and useful to follow ventricular size. CT with reconstruction is useful to assess bony defects. MRI is the test of choice with or without MRA to determine if neural tissue is involved and nature of adjacent vascular structures.

Other cephalic anomalies associated with Sincipital encephalocele include cleft lip, cleft plate, malformation of the nasal tip, microphthalmia , corneal opacity, and corpus callosum agenesis or lipoma.

D/D for Sincipital encephalocele dermoid cyst; nasal glioma; sinus pericranium; teratoma; ethmoid meningioma and angioma.

The exact etiopathogenesis of Sincipital encephalocele is unknown, a variety of mechanisms have been presented. Genetic or environmental factors interfering with closure of anterior neuropore (approximately day 24) can cause lethal conditions such as exencephaly or anencephaly. Therefore, less severe degrees arrest could potentially cause sublethal conditions such as encephaloceles. Another mechanism is mesodermal insufficiency in which neural tissue herniates through a mesodermal defect. Ectodermal adhesions between neuroectoderm and ectoderm preventing mesoderm from

surrounding the neural tube.

Untreated encephaloceles may continue to enlarge because of increasing brain herniation and increased deficit may follow. Early operation may prevent this complication. The primary goals of operation for sincipital encephalocele are closure of the dura at the level of the cranium, replacement and/or removal of extracranial cerebral tissue, and restoration of cranial contour with good skin coverage.

Contrary to the prognosis for occipital encephalocele, that for children with sincipital encephalocele is excellent. In the absence of the complications of infection and hydrocephalus, one may anticipate normal intellectual development for these children. [4][5]