Objectives: Lateral sphenoid sinus wall meningoceles are unusual entities. Several etiologies may be related to them; such as congenital defects, head trauma or bony dehiscences caused by neoplastic/inflammatory process erosion. Incomplete fusion of several cartilaginous sphenoid bone precursors may end up being a persistent canal. We present a four patient case series of lateral sphenoid sinus wall meningocele, repaired through an expanded endonasal approach.

Material and methods: After retrospectively reviewing anterior skull fossa CSF leakages repaired through an EEA from January 2013 to December 2015 in our department, we obtained four lateral sphenoid sinus wall defects; whose clinical and radiological features will be described. Furthermore, reconstructive surgery results are shown.

Results: Among our series, no head trauma or neoplastic/inflammatory etiologies were seen. All of them were referred to our department after brisk high-flow nasal CSF leakages. One-nostril EEAs were performed on them, noting temporal lobe herniation inside the sphenoid sinus through large bony breaches in two cases, which required encephalocele resection. Using a pediculated nasoseptal flap, no recurrences have been reported after a 12 month follow up.

Conclusions: Congenital lacking ossification of the lateral wall of the sphenoid sinus, might lead to nasal CSF leakages linked to meningoencephalocele. Nasoseptal flaps are a valid treatment option to achieve restoration.

Key words: Endoscopic approach. Meningoencephalocele. Cerebrospinal fluid leak. Endoscopic skull base.