Extended Frontobasal Approach (EFB) to Skull Base

Background: EFB approach includes a bilateral orbito-fronto-ethmoidal osteotomy to provide adequate midline exposure from anterior cranial fossa to sphenoclival region. It is especially useful for extensive anterior and anterolateral skull base tumors.

Methods: 26 patients (age range 8-75 years; male: female ratio = 20:6) with chordoma (n = 8), esthesioneuroblastoma (n = 4), mesenchymal tumor (n = 2), fungal granuloma (n = 2); and one case each of osseous haemangioma, ethmoidal schwannoma, chondroma, ossifying fibroma, haemangiopericytoma, eosinophilic granuloma, giant cell tumor, leimyosarcoma, chondrosarcoma, and adenoid cystic carcinoma were operated. EFB was combined with sublabial midline degloving (n = 2), orbitozygomatic osteotomy and subtemporal-infratemporal approach (n = 4), and frontotemporal transsylvian approach (n = 3). 3 patients with parasellar tumor extension did not tolerate balloon test occlusion.

Results: Two patients in preoperative altered sensorium due to raised intracranial pressure died due to meningitis. Recurrence required reoperation in one patient with chordoma and ossifying fibroma, respectively. There was significant improvement in symptoms of raised intracranial pressure and nasal obstruction in a follow up ranging from 22 months to 5 years. Patients with malignant lesions had a range of survival from 2–5 years. The main morbidity included CSF rhinorrhoea and meningitis.

Conclusions: EFB approach provides an excellent visualization and decompression of anterior skull base, nasopharynx, optic nerves, sphenoid sinus, medial aspect of the cavernous sinus and clivus. Addition of maxillotomy or orbitozygomatic osteotomy enables access to lesions extending laterally along temporal base and greater wing of sphenoid. Performing surgery in two distinct compartments by first removing extradural tumor; and, subsequently reconstructing a vascularized flap that exteriorizes the potentially infected nasoethmoidal region from the cranial cavity before intradural surgery minimizes the risk of infection. However, EFB requires extensive soft tissue and bone dissection; has potential for CSF leak and infection; and causes bilateral olfactory denervation.