Spontaneous cerebrospinal fluid fistula secondary to transethmoidal meningoencephalocele in an adolescent

Abstract

Background: transethmoidal meningoencephalocele is a rare congenital malformation of the anterior skull base. Although it is usually diagnosed in the neonatal period or childhood, late-onset forms are exceptional and can manifest as spontaneous rhinorrhea, complicating diagnosis.

Objectives: to describe a case of transethmoidal meningoencephalocele diagnosed during adolescence and to present the clinical and imaging findings, as well as the surgical strategy used for its treatment.

Case description: a 15-year-old male patient, with no relevant medical history, presented with spontaneous rhinorrhea of 3 months' duration. Computed tomography revealed a congenital osteodural defect of the ethmoid bone, while magnetic resonance imaging confirmed the protrusion of meningoencephalic contents into the nasal cavity, consistent with a transethmoid meningoencephalocele. One year prior, a lesion interpreted as a nasal polyp had been resected.

Surgery: an anterior skull base repair was performed via a bicoronal approach and bifrontal craniectomy, with reduction of the herniated tissue, closure of the osteodural defect using periosteum and sealant, treatment of the frontal sinus, and cranial reconstruction. The postoperative course was favorable, without complications or recurrence of rhinorrhea.

Conclusion: spontaneous rhinorrhea in adolescents should raise suspicion of osteodural defects of the skull base. Computed tomography and magnetic resonance imaging are essential for diagnosis and surgical planning, while early repair allows for fistula resolution and prevention of infectious complications.