Characteristics and surgical strategies for posterior clinoid process meningioma: two case reports and review of the literature.

Clinical and radiological features or characteristics of posterior clinoid process (PCP) meningiomas have rarely been described because of their extreme scarcity and terminological confusion. Therefore, the strategies in the surgical intervention for PCP meningiomas have not been well established. Moreover, the presence of deep and critical neuroanatomical structures and relatively high morbidity, which can be difficult to predict preoperatively, make their surgical excision more challenging. We report two surgical cases of PCP meningioma and discuss the appropriate assessment of preoperative features and surgical strategies with review of the literature. Our study suggests that PCP meningioma may be characterized by the anterior displacement of internal carotid artery, and infero-laterally shifted posterior communicating arteries, and homonymous hemianopsia, a distinctive clinical feature. One of the key issues in PCP meningioma surgery is preservation of the optic nerve. Unlocking the optic nerve by anterior clinoidectomy and dissection, the falciform ligament is the important step to preserve vision for larger tumors. Complication with the perforators is also hazardous of these challenging surgeries than anterior clinoid meningiomas for their specific neuroanatomical structures and might not be feasible to avoid even with additional techniques and critical monitoring. A combination and multi-staged-surgical approach can be options of tailor-made surgical strategy in cases with tumor adhesion to the perforators.