Frontal sinus encephalocele masquerading as a nasal polyp and mucocele: Beware the posterior table defect

• Encephaloceles are herniations of intracranial contents through the skull named by the contents of the herniated sac. • Meningoceles contain meninges • Meningoencephaloceles contain meninges and brain. • Types of encephaloceles • Congenital • Acquired • Traumatic • Injury vs. iatrogenic • Spontaneous/non-traumatic • High vs. normal pressure • Congenital • Occur in 1:4000-5000 births worldwide • Occipital: posterior skull base, most common • Sincipital: root of nose • Nasofrontal, nasoethmoid, and nasoorbital • Basal: intranasal, into pharynx • Transethmoidal, sphenoethmoidal, transsphenoidal, and sphenomaxillary • Detect antenatal with ultrasound or elevated-fetoprotein, or post-natally by external nasal bridge widening, hypertelorism, orbital dystopia and facial elongation Frontal sinus encephalocele masquerading as a nasal polyp and mucocele: Beware the posterior table defect CASE REPORT DISCUSSION ABSTRACT Objective: To present a case report of a frontal encephalocele that mimicked as a nasal polyp and erosive mucocele Study design: Case report from a military tertiary care referral center. Methods: Report of a unique case with discussion of possible preventable pitfalls and review of the pertinent literature. Results: 60 year old male presented with 9 months of worsening unilateral nasal obstruction, chronic rhinorrhea, and frontal sinus pressure. He failed medical management and denied recurrent sinusitis, nasal polyps, sinus surgery, or head trauma. Examination revealed a large polypoid mass appearing to emanate from the middle meatus, nearly occluding the left nasal cavity. Pre-operative CT demonstrated a soft tissue mass centered in the nasal cavity, opacifying the left ethmoids and frontal sinus. A small bony dehiscence of the postero-lateral frontal sinus wall appeared secondary to a mucocele. The patient underwent septoplasty and endoscopic removal of the lesion, which appeared consistent with a large polyp. The final pathology demonstrated mature glial and neuronal elements. Post-operatively he reported clear rhinorrhea and further history revealed similar clear rhinorrhea pre-operatively that ceased as his obstruction worsened. Flexible endoscopy through the frontal recess demonstrated pulsatile soft tissue and a left frontal lobe encephalocele was appreciated on MRI. The patient underwent bifrontal craniotomy, reduction, and layered repair without incident. Conclusions: Encephaloceles are most commonly reported in pediatric populations, or adults with prior trauma or iatrogenic injury. This case report, with associated photographs and imaging studies, demonstrates an unusual patient presentation of sinus pathology that may warrant more extensive pre-operative history and work up. • After removal of his nasal splints at 1 week, a flexible endoscope passed easily through the frontal recess into …