Meningiomas originate from the endothelial cells lining the arachnoid villae and are closely related to dural sinuses and veins. Meningiomas are benign but locally aggressive tumors, they can be histopathologically grouped into four categories which correspond to the invasiveness of the tumor. Meningiomas arising on the petrous bone surface in the posterior fossa do so in relation with the superior or inferior petrosal sinuses as well as the sigmoid sinus. As with acoustic neuromas, these tumors produce their clinical signs and symptoms not by invasion but by displacement of the neural structures. The signs and symptoms of meningiomas are similar to those of ANs.
Small tumors produce hearing loss, tinnitus, and imbalance.
Larger tumors also produce signs and symptoms of other cranial nerve involvement and hydrocephalus. Audiovestibular symptoms are usually the first indication of a posterior fossa meningioma, although a higher proportion of patients experience trigeminal symptoms as compared with acoustic neuromas. The distinction between meningiomas of the petrous bone and other tumors such as acoustic neuromas can be made with reasonable accuracy on the basis of morphologic characteristics on imaging studies. Unlike acoustic neuromas, meningiomas are usually eccentrically positioned in relation to the internal auditory canal. In addition, meningiomas involve the middle cranial fossa with higher frequency than acoustic neuromas and are broad based on the surface of the temporal bone.