Image-guided resection of spheno-orbital skull-base meningiomas with predominant intraosseous component

Although meningiomas of the spheno-orbital region commonly result in hyperostosis, intraosseous meningiomas, which feature extensive full thickness infiltration of the anterolateral skull base, are rare. In this study, we assess the value of image guidance during surgery for intraosseous spheno-orbital skull-base meningiomas in achieving safe and maximal abnormal bone resection. Only cases with a full thickness and extensive intraosseous component were included. Image guidance was used to guide drilling of hyperostotic bone. Extensive resulting defects of the orbital wall were reconstructed with titanium mesh. Post-operative CT scans were used to assess completeness of abnormal bone resection in the skull base, and MRI scans used to evaluate residual intradural disease. Operative complications to neurovascular structures in adjacent foramina were recorded. Nineteen patients with full-thickness intraosseous spheno-orbital meningiomas underwent image-guided resection. Anterior clinoidectomy to variable extent was necessary in 11 cases with decompression of the optic canal in five. In ten cases, hyperostotic bone was drilled from the middle fossa around the exit foramina of the trigeminal nerve and base of the pterygoid plates. Proptosis was corrected in all cases, and of 11 patients presenting with reduced visual acuity, symptoms improved or stabilized in ten cases. Post-operative CT scans confirmed gross resection of abnormal bone in all cases, but limited residual tumor was present around the cavernous sinus or orbital apex in eight patients. One patient died from a pulmonary embolism, the only mortality of the series. One patient had worsening of pre-existing poor visual acuity, and three patients had worsening of pre-existing ophthalmoplegia. Five patients developed new facial numbness post-operatively, which persisted in three cases. Intra-operative image guidance allowed total or near-total resection of the hyperostotic skull base around the cranial nerve foramina with minimal morbidity in a group of patients with extensive spheno-orbital meningiomas.