Avances en cirugia cerebral

Neurol Clin 25 (2007) 975–1003

Advances in Brain Tumor Surgery
Ashok R. Asthagiri, MDa,*, Nader Pouratian, MD, PhDb, Jonathan Sherman, MDb, Galal Ahmed, MDb, Mark E. Shaffrey, MDb
b a National Institutes of Health/NINDS, Bethesda, MD, USA Department of Neurological Surgery, University of Virginia, P.O. Box 800212, Charlottesville, VA 22908-0212, USA

There is perhaps no more dauntingchallenge in all of medicine than the management of patients diagnosed with a brain tumor. Wielding what now would seem elementary neurosurgical concepts in antisepsis, anesthesia, and preoperative localization, Rickman Godlee operated on a 25-year-old Scottish farmer who presented with focal motor seizures and progressive hemiparesis in November 1884. The patient underwent surgical resection of anoligodendroglioma, clinically localized to the region of cortical substance near the upper third of the rolandic fissure, but eventually succumbed to complications of meningitis 28 days later. Although an undesirable outcome, the operation highlighted the new belief of brain tumor vulnerability and ushered the field forward into the modern age of brain tumor surgery. Contemporaneous with early successin the treatment of intracranial extra-axial masses, such as meningiomas and schwannomas, surgeons were met with equilibrating results from surgical management of intrinsic brain tumors. Only in the past 20 to 30 years have we witnessed significant improvements in microneurosurgical strategies and techniques that have revolutionized the management of primary glial neoplasms and help shed the dogmaof their unresectability [1]. Microneurosurgical techniques, however, with the use of the operating microscope alone, have limitations in the definition of the boundaries of glial neoplasms and of the localization of eloquent cerebral cortex and subcortical white matter. Important technologic adjuncts have come to the forefront over the past 15 years that have allowed neurosurgeons to enhancevolumetric resections and open surgical corridors to lesions in eloquent cortices while curtailing

* Corresponding author. E-mail address: asthagiria@ninds.nih.gov (A.R. Asthagiri). 0733-8619/07/$ - see front matter Ó 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.ncl.2007.07.006 neurologic.theclinics.com

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surgical morbidity and improving survival. These recentsurgical developments have centered on identification of eloquent cortex through preoperative functional imaging, awake craniotomy, and cortical stimulation; fusing preoperative structural data with real-time surgical anatomy via frameless neuronavigation systems; and real-time image-based guidance of tumor resection with intraoperative MRI (iMRI). Another area within neuro-oncology displayingsignificant change has been the development of surgical methods to deliver local adjunctive radiotherapy and chemotherapy, historically restricted to the extraoperative treatment armamentarium. Before delineating the usefulness of these advances, this article reviews a fundamental query: the putative benefit of maximal resection in the treatment of gliomas.

Low-grade gliomas The World HealthOrganization classification of low-grade gliomas encompasses several grade I and II tumors with heterogeneous clinical, pathologic, and molecular features [2]. Chief among these are grade II diffuse astrocytomas, oligdendrogliomas, and oligoastrocytomas, all of which have malignant potential and together represent approximately 20% of gliomas [3]. The prognostic effect of extent of resection in surgery forlow-grade gliomas, as it relates to clinical outcome, has not been evaluated specifically in any randomized study. Thus, all available management strategies are satisfactory treatment options, yet none is supported by enough high-quality evidence to be considered a treatment standard. Most authorities agree that surgery or biopsy at the time of initial detection, rather than at the time of...