Basal meningocele is a rare midline bony defect of the base of the skull which may allow protrusion of the meninges and their contents. Herniated meninges in such cases may be found in the nasal cavity, nasopharynx, the sphenoid and ethmoid sinuses, the orbit, and the pterygopalatine fossa, the site depending on the location and size of the bony defect.

The basal meningocele frequently escapes the diagnosis and may be detected at adult age. MRI is the imaging diagnostic procedure of choice since it allows to precisely identifying the presence of meninges, brain parenchyma and blood vessels inside the bone defect. Besides, it provides broad encephalic anatomic evaluation which facilitates the identification of other anomalies.

Basal meningocele are classified in accordance with their location as transsphenoidal, sphenoorbital, sphenoethmoidal, transethmoidal, or sphenomaxillary. Although the transethmoidal is the most frequent, these are all rare anomalies, accounting for about l 5% of all encephaloceles. Basal meningocele are often associated with other midline anomalies such as hypertelorism, broad nasal root, cleft lip, and cleft palate.

We report here  case of a child, 55-day-old,  with a transethmoidal meningocele with the chief complaint of getting cyanotic when he was drinking milk. This meningocele may presents as a mass in the nasopharynx, masquerading as nasal polyps or enlarged adenoids.

Key word: basal meningocele