Role of Skull Base Surgery for Cavernous Sinus and/or Petroclival Meningiomas(<SPECIAL ISSUE>Skull Base Surgery in the Radiosurgery Era)

Abstract

Recently, various radiation therapies, such as stereotactic radiosurgery, fractionated stereotactic radiotherapy, intensity-modulated radiation therapy, and proton-beam radiation, are available for treating skull base meningiomas. The role of skull base surgery for cavernous sinus and/or petroclival meningiomas is a maximal resection of the tumor while preserving the neurological functions since we can expect better growth control for the smaller remnant tumor. To reduce the volume of the remnant tumor, we should resect cavernous sinus meningiomas until the meningeal layer of the lateral cavernous wall. If the tumor can be dissected from the trigeminal nerve, any tumor in the Meckel's cave should be removed. Functioning cranial nerves and vessels must be preserved. If the tumor cannot be dissected from the neurovascular structures, the neurovascular structures should be preserved by leaving the tumor around them. When preoperative images show a pial blood supply or severe brainstem edema, the tumor should not be dissected from the brainstem. During surgical procedures, we should stop dissection if the motor evoked potential amplitude deteriorates or if the tumor involves the branches of or perforators from the basilar artery. On the other hand, tumor that extends into the extracranial space should be removed since the extracranial tumor usually shows aggressive invasion to the skull base bone, the muscles, nerves, or mucous membranes. It is important to clarify the strategy and the goal of tumor resection for individual patients