NEURORADIOLOGY


Case 31:
Newborn with a soft mass lesion at the bridge of the nose. What is the diagnosis?

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Examination reveals soft tissue mass lesions involving the retroconic, and extraconal spaces of both orbits. Small soft tissue lesion is seen near the posterior wall of the right maxillary sinus. Minimal enhancement is noted on contrast examination.

Diagnosis

Frontal encephalocele

Discussion

Encephaloceles signify the herniation of neural tissue through defects in the skull. They may contain meninges (meningocele) or brain matter and meninges (encephalomeningocele), or they may communicate with a ventricle (encephalomeningocystocele). Encephaloceles have an etiology similar to that of gliomas. No familial pattern has been demonstrated with these lesions. Association with other diseases (eg, Ehlers-Danlos syndrome, frontonasal dysplasia), however, may suggest a genetic component.

Nasal encephaloceles can be divided into 2 types: sincipital (60%) and basal (40%).
The sincipital form is divided into subtypes as follows:
(1) the nasofrontal (40%), which exits the cranium between the nasal and frontal bones;
(2) the nasoethmoidal (40%), which exits between the nasal bones and nasal cartilages; and
(3) the nasoorbital (20%), which exits through a defect in the maxilla frontal process. Sincipital encephaloceles typically present as soft compressible masses over the glabella.

The basal form is divided into subtypes as follows:
(1) the transethmoidal, which exits through the cribriform plate into the superior meatus, extending medial to the middle turbinate;
(2) the sphenoethmoidal, which exits through the cribriform plate, between the posterior ethmoid cells and sphenoid, to present in the nasopharynx;
(3) the sphenoorbital, which enters the orbit via the superior orbital fissure and may produce exophthalmos; and
(4) the transsphenoidal, which herniates in the nasopharynx via defects posterior to the cribriform plate. Basal encephaloceles may remain hidden (clinically) for years.

Biopsy is strongly contraindicated due to risk of infection and meningitis. Treatment involves surgical excision with repair of the bony defect. Often a craniotomy is necessary to approach the encephalocele.


Dr Sanjeev Mani, Mumbai