History of Management of Supratentorial High-Grade Gliomas in Children

Understanding of Disease

• Late 20th century – changing view on treatability: The neurosurgical and oncologic culture and feelings about HGGs have, over time, moved toward a more hopeful, yet guarded outlook. Indeed, particularly with regard to GBM, pessimism and futility have permeated the surgery and science of this disease for a century. However, as science has advanced to yield better understanding of the biology of these tumors, in combination with advances in chemotherapy, biological therapy, radiation, technology in the operating room, and surgical technique, new concerted efforts are being made to bring AAs and GBMs into the realm of treatable brain tumors.

Technological Development

• Improved imaging: Preoperative imaging, including high resolution CT and MRI, fMRI, and DTI, have helped to locate and delineate both brain tissue affected by tumor and eloquent brain that may be spared injury if not involved with the tumor. Indeed, much of this functional imaging has replaced the need for extraoperative monitoring.
• Improved instrumentation: Neurosurgery as a surgical subspecialty has always been affected by advances in technology, and these advances have enhanced the surgeon’s ability to perform safer, more effective resection of brain tumors. Such advances over the years have included the cavitron ultrasonic surgical aspirator (CUSA) and improvement in the control of blood loss, both by bipolar electrocautery and by the use of various hemostatic materials. Endoscopy has aided in visualizing the intraventricular environment while allowing for less invasive surgery, particularly with regard to biopsies and ETV, often obviating the need for permanent CSF diversion.
• Introduction of intraoperative imaging: Intraoperative imaging, which includes ultrasound, CT, and MRI, can aid in giving the surgeon real-time information regarding location, extent of tumor location, and the presence of potential concomitant complications such as brain collapse or the development of a hematoma.
• Improved knowledge of tolerance of CNS for surgery: Intraoperative neuromonitoring and extraoperative mapping have helped identify functionally critical and eloquent areas of the brain that can be avoided during surgery.
• Improved intraoperative navigation: Frame-based stereotaxy, allowing for precise location of deep-seated lesions, as well as subsequent frameless navigation systems, also allowing for location of critical vessels and structures in addition to real-time volumetric analysis of extent of resection, have greatly aided the surgeon in removing HGGs.

Surgical Technique

• Introduction of microneurosurgery: The surgical skills and techniques vary from surgeon to surgeon and from decade to decade, but the advent of surgical tools has improved surgery for children with HGGs. The operating microscope and the microinstruments needed to take advantage of the magnification and improved lightening have allowed for more aggressive surgery in previously avoided areas, such as the CSF cisterns, the base of the skull, and the brainstem. Microsurgery, in combination with intraoperative technological advances mentioned above, has helped to avoid major neurological deficits, even with aggressive resections in eloquent or critical areas.
• Increasing minimalization of surgery: Given the quality and availability of radiologic imaging, the state of anesthesia, and the instruments and intraoperative adjuncts available at any given time in modern medical history, the actual surgical technique involved in successfully operating on these tumors has progressed from, depending on tumor location and individual patient presentation, gross macrosurgery aimed at complete resections with wide, ill-defined margins and significant morbidity, to finesse microsurgery with image guidance and intraoperative monitoring aimed at clinically effective resections with minimal neurological deficit and morbidity.
• Knowledge of importance of extent of resection: Some have argued that the extent of surgical resection, particularly in the case of GBMs, is not significant in the outcome of the child. There is increasing evidence, however, that cytoreductive surgery may be of benefit, and as such, the better the resection, particularly with AAs, the better the chances are for survival.