Meningiomas involving the cavernous sinus: histological factors affecting the degree of resection.

Despite advances in the surgical treatment of meningiomas located at the skull base, surgery for meningiomas involving the cavernous sinus remains controversial. The controversy centers on whether complete resection of such a meningioma is possible while preserving cranial nerve function. To evaluate this question, the authors examined six patients with benign meningiomas involving the cavernous sinus. The pathological features of these tumors were evaluated and compared with the normal histoarchitecture of the cavernous sinus. The tendency of these tumors to be infiltrative is evident and this seems to occur along connective tissue planes within the cavernous sinus. This invasiveness can be explained by the peculiar structure of this region. The trigeminal nerve and ganglion seem to be particularly prone to invasion; this does not correlate with the degree of preoperative impairment of nerve function. Internal carotid artery invasion occurs frequently and can be seen even when there is no narrowing of the artery on arteriography. The pituitary gland can also be invaded by the tumor, which penetrates the thin dural barrier.