Middle Fossa Approach to a Temporosphenoidal Encephalocele -Technical Note-

Abstract

Temporosphenoidal encephalocele (TSE) is a rare entity caused by herniation of the anteromedial temporal lobe into the sphenoid sinus (SS) through a middle fossa (MF) defect. A 45-year-old woman presented with a spontaneous TSE manifesting as a 4-year history of recurrent cerebrospinal fluid rhinorrhea and meningitis. Coronal computed tomography showed a skull defect in the superior wall of the right lateral recess of the SS. This homogeneous intrasphenoidal lesion appeared hypointense on T(1)-weighted magnetic resonance (MR) imaging and hyperintense on T(2)-weighted MR imaging. The patient underwent a frontotemporal craniotomy and extradural MF exploration. The encephalocele was amputated and the temporal base dura primarily sutured and reinforced with fat graft. The MF hole was plugged with temporalis fascia and a calvarial graft layered over the bone defect. Histological examination confirmed meningoencephalocele. Rhinorrhea resolved and the patient remained asymptomatic. Resection of an anteromedial TSE and closure of the craniodural defect in the MF floor via a less invasive extradural skull base approach is effective.