Cavernous Sinus Meningioma

Abstract

Cavernous sinus tumors most frequently are revealed by oculomotor deficit, ptosis, diplopia, anisocoria, or complete ophthalmoplegia. Involvement of the trigeminal nerve with facial numbness or facial pain can occur. Compression of the internal carotid artery with reduction of the arterial lumen has been held responsible for ischemic events. Two types of cavernous sinus meningiomas have to be distinguished: some meningiomas arise from the lateral dural wall (Fig. 24.1) while others are developed exclusively inside the cavernous sinus. The main features are enlargement of the cavernous sinus and thickening of its lateral wall, which is markedly hypointense on T2WI (Fig. 24.2). A dural tail, linear meningeal thickening, and enhancement extending from the edge of the tumor to the ipsilateral tentorium are almost always present but not specific. It can be observed in other extra-axial lesions, such as schwannoma, metastasis, lymphoma, pituitary diseases, and granulomatous disorders. The dural tail reflects the neoplastic dural infiltration or reactive vascularity, or both, draining in the adjacent dura. The tumor can extend anteriorly toward the optic canal, the superior orbital fissure, the great wing of the sphenoid, and posteriorly toward the Meckel cave and the prepontine cistern. Encasement of the internal carotid artery and constriction of its lumen is common (Fig. 24.3). 3D TOF MRA can help to visualize the internal carotid artery stenosis and assess the intracranial collateral vascularization. Cavernous sinus meningiomas frequently extend into the sella turcica, pushing the pituitary gland toward the opposite side. The medial limit of the tumor is usually well defined on T2WI, owing to the hypersignal of the meningioma in comparison with normal pituitary gland, while CE T1WI usually demonstrates similar homogeneous enhancement of meningioma and pituitary gland. Dynamic MRI can help to distinguish the meningioma from the compressed normal pituitary gland. A cavernous meningioma with intrasellar extension may be responsible for an enlargement of the inferior intercavernous sinus (Fig. 24.4). Multiple meningiomas of the sellar region can occur (Fig. 24.5). MRI appearance of cavernous sinus meningioma is usually typical. The main differential diagnosis is pituitary adenoma with cavernous sinus invasion. In some cases, cavernous hemangioma, metastasis, lymphoma, trigeminal schwannoma, or thrombosed intracavernous internal carotid artery aneurysm can simulate a meningioma. Looking at the sphenoid sinus itself may be of precious help, as intracavernous meningiomas may invade it by passing through its bony walls after thickening them instead of destroying them, a feature not encountered in other lesions (Fig. 24.6).