Brain Herniation After Endoscopic Transnasal Resection of Anterior Skull Base Malignancies

BACKGROUND: Endoscopic endonasal approaches, when appropriate, allow a less invasive method to remove anterior skull base cancer than traditional external transfacial/craniofacial approaches. The resultant skull base defect can be significantly large, potentially extending from the posterior table of the frontal sinus to the tuberculum sellae in the sagittal plane, and from one lamina papyracea to the other in the coronal plane. However, frontal lobe herniation after such expanded endoscopic resection has been considered more of a theoretical than a practical occurrence. OBJECTIVE: To report the occurrence of frontal lobe herniation into the sinonasal cavity after expanded endonasal approaches, and to analyze causes and pathogenetic mechanisms of this unusual complication, proposing how it could have been prevented. METHODS: Two cases have been observed in 2 different skull base referral centers in the United States and Italy. Surgical and perioperative complications, postoperative course, and need for revisions were analyzed. RESULTS: Available data support the hypothesis that this complication is not attributable to the size of the anterior skull base defect, to the surgical technique, or to the materials used for the reconstruction. We found that 1 possible contributing factor may be the presence of increased intracranial pressure associated with obesity and obstructive sleep apnea, observed in both patients. CONCLUSION: Frontal lobe herniation must be considered as a possible, albeit rare, complication of expanded endoscopic anterior skull base resection. Preoperative investigations concerning the presence of obstructive sleep symptoms as well as proper identification of neuroimaging signs of intracranial hypertension are recommended for such cases.