Complex technical methodologies and their applications in the surgery of intracranial meningiomas.

As neurosurgery moves into the twenty-first century, improved visualization/localization techniques, neuromonitoring, and advanced instrumentation will become standards of care for all intracranial procedures. This article has focused on current available technologies that can be used to facilitate operations on intracranial meningiomas. Preoperative anatomic localization with MR imaging, CT, MR angiography, and angiography are standard techniques. Preoperative functional assessments with MR imaging, magnetic source imaging, PET, and functional MR imaging are crucial to recognize and preserve eloquent adjacent cortex. Pathologic correlations with preoperative imaging (i.e., MR imaging) may help to predict the histopathology. Perioperative rehearsal of the operation can be performed. Intraoperative anatomic localization is important to minimize the craniotomy, dural opening, and passage through normal neural structures. An impressive array of new technologies are currently available, including real-time ultrasonography, frame-based stereotaxy (CT, MR imaging PET), frameless stereotaxy (acoustic localization, neuronavigators, real-time visualization), robotics, neuroendoscopy, and intraoperative dye administration. Increased understanding of the function and individual variability of the human cortex underscores the importance of intraoperative functional localization by electrocorticography and optical imaging. Continuous intraoperative neuromonitoring of sensory (SSEPs, BAERs, visual evoked potentials) and motor evoked potentials is now standard during many intracranial procedures. Complex adjunctive instrumentation, such as the ultrasonic aspirator and the laser, are part of the contemporary armamentarium for meningioma surgery. As we have stated in a previous article, "Developmental trends imply realization of three major directions of technical neurosurgery: (1) precise preoperative simulation, (2) minimization or avoidance of transcranial operative corridors, [and] (3) increased refinement of technical adjuvants--both physical and molecular." The end point of these technical advances is to improve precision and safety and will enhance the outcome in each surgical procedure so that one day we will be able to operate on patients with intracranial lesions with minimal morbidity.