Comparative Study Between Different Approaches to CPA -Petroclival Meningiomas

There are several lesions arising in the petroclival region. The most frequent tumor is the petroclival meningioma, followed by chondrosarcomas, chordomas, schwannomas of the cranial nerves V and VII, and other malignant tumors [1, 2, 3, 4, 5].

Petroclival meningiomas are tumors of the skull base that present a formidable challenge to surgical resection because of their deep location and relationship to vital neurovascular structures. In the majority of the cases they are benign tumors, but may involve or infiltrate the skull base bone, the dura mater, the brainstem, and all important neurovascular structures of this region. The petroclival region comprises the anatomical location of the body of the sphenoid bone, the anterior central portion of the occipital bone, and is bordered on the lateral aspect by the petrous apex. The roof of this space is formed by the petroclival ligaments and the tentorium. This space contains important neurovascular structures that are frequently involved or displaced by the tumor in a variable pattern. The basilar artery with its branches may be embedded or displaced by the meningioma. The petrosal vein is often displaced posteriorly by the tumor. Cranial nerves III and IV are usually displaced upwardly and the nerve VI is often surrounded by tumor. Petroclival meningiomas have their origin medial to cranial nerves V, VII, VIII, IX, X, and XI, and reach the tentorium . They frequently extend to the middle cranial fossa, cavernous sinus, prepontine space, and down to the foramen magnum. These tumors frequently compress the brainstem making total removal very difficult or impossible without neurologic deficits. cerebellopontine angle (CPA) and low clivus meningiomas may reach these areas. These lesions usually need different surgical approaches as transpetrosal approach ( anterior, modified and combined ) and retrosigmoid approach