Endoscopic Endonasal Transcribriform Approach for Anterior Skull Base Tumors Involving the Cribriform Plate: Indications, Techniques, and Results in 13 Patients

Introduction: Tumors involving the anterior skull base have traditionally been treated with a transcranial or craniofacial approach. The endoscopic endonasal transcribriform approach (EEA-TC) is an extracranial approach that provides direct visualization and exposure of the ventral anterior skull base without brain retraction or manipulation of neurovascular structures. In this study, we reviewed our experience with EEA-TC for surgical removal of anterior skull base tumors.

Methods: Retrospective review of a prospective database of endoscopic skull base procedures performed within a 2-year period revealed 13 patients that underwent EEA-TC for ASB tumors involving the cribriform plate. Nine underwent a pure endonasal approach. Four underwent a combined cranionasal approach (EEA-TC plus transbasal craniotomy) because of significant intracranial tumor extension. The pathologies included olfactory groove meningioma (n = 4), esthesioneuroblastoma (n = 3), sinonasal teratocarcinosarcoma (n = 1), olfactory schwannoma (n = 1), osteoblastoma (n = 1), melanoma (n = 1), sinonasal small cell neuroendocrine carcinoma (n = 1), and adenoid cystic carcinoma (n = 1). All patients underwent multilayer reconstruction of large cribriform skull base defects using autologous fascia lata and AlloDerm graft followed by a vascularized pedicled nasoseptal flap.

Results: Gross-total resection was achieved in 84.6% (11 cases), and near-total resection was achieved in 15.4% (2 cases). Postoperative complications occurred in two patients, including a postoperative hematoma and delayed brain abscess in one patient in the pure EEA-TC group, and pneumocephalus and subsequent bone flap infection in another patient in the combined cranionasal group. There were no postoperative CSF leaks. Mean follow-up was 10 months (range: 1 to 23 months).

Conclusion: The EEA-TC is a safe and viable approach for resection of benign and malignant ASB tumors involving the cribriform plate. This can be combined with a transcranial approach in cases with significant intracranial extension. Meticulous multilayer reconstruction of these large skull base defects with nasoseptal flap repair can minimize the risk of postoperative CSF leakage.