Chapter 20 - Surgery of brain tumors asleep

While total and even subtotal resection in surgery of brain tumors significantly improves life expectancy, disconnection of essential cerebral networks leads to neurological deficit and impairs quality of life. As classical cortical localization of brain functions has moved toward a hodological perspective, total and “supratotal” resection exceeding tumor borders according to functional margins has been proposed. These functional margins, rather than cortical networks, consist of subcortical white matter tracts. Although awake surgery is often advocated, when operating in situations of poor compliance, such as children or patients with preexisting neurological deficits, there may be a requirement for a different surgical strategy. One such strategy is the use of intraoperative neurophysiological monitoring (ION), enabling functional identification of functionally defined, but anatomically ambiguous, cortico-subcortical structures through mapping and monitoring techniques. Here we review well-established ION practices for preservation of function, with particular focus on motor and visual ability.