RT Book, Section A1 Ropper, Allan H. A1 Samuels, Martin A. A1 Klein, Joshua P. A1 Prasad, Sashank SR Print(0) ID 1199445449 T1 Intracranial Neoplasms and Paraneoplastic Disorders T2 Adams and Victor's Principles of Neurology, 12e YR 2023 FD 2023 PB McGraw-Hill Education PP New York, NY SN 9781264264520 LK neurology.mhmedical.com/content.aspx?aid=1199445449 RD 2024/10/03 AB The importance of tumors of the nervous system in both neurology and general medicine derives from their great variety; the numerous neurologic symptoms they cause; the destruction and displacement of brain tissue and most of all, their lethality. The nature of practice for brain tumors has continuously changed as a result of advances in anesthesiology, stereotactic and microneurosurgical techniques, focused radiation therapy, and the use of new chemotherapeutic agents. Moreover, our understanding of the genetic aspects of brain tumors is undergoing vast alteration, which offers the prospect of new treatments. Perhaps the largest inception in the field of brain tumors in recent years has been the WHO 2021 classification system (also called in the chapter, WHO5) which is based largely on genetic alterations within tumors, some of which are pathogenic and most of which align with prognosis to a greater extent than histologic features, which in the past had dominated our ideas about these disorders. This has rearranged nosology in the field, dropping formerly common terminologies and introducing new ones that are incorporated into appropriate sections of this chapter. Deeper study of genetic variants is likely to continue but the problem of defining disease categories as contrasted with surrogate markers of tumor behavior will take time to resolve and we are currently at a point of using what are undoubtedly transitional classifications.