Abstracts

Intraoperative or perioperative localization of language or motor function is often performed prior to excision of mass lesions adjacent to eloquent cortex or with surgery for intractable epilepsy. Electrocorticography is typically accomplished with electrical stimulation through subdural electrodes or via direct stimulation using devices such as an Ojemann stimulator. Current methods have significant limitations. Electrical stimulation is time consuming, disrupts normal brain function, may be false localizing if the stimulation spreads and can induce seizures. We present here a novel signal processing and visualization method that passively maps language and sensorimotor function. Using autoregressive analyses and mathematical modelling techniques, the properties of resting cortical activity are determined. Language and motor tasks are performed in the awake patient and rapid identification of the brain areas associated with these functions is achieved. This method can topographically visualize brain signal changes in real time, and can thus be used in a highly exploratory and non hypothesis-driven fashion to identify and localize brain function associated with tasks or abnormal activity. In multiple patients with subdural grid recordings, activity at distinct and reproducible grid locations corresponds to specific tasks. The acquisition of interpretable averaged topographic findings takes less that one minute. Initial tests of this method suggest that, with further confirmation and development, it could largely or entirely eliminate the need for electrical stimulation to map cortical function prior to resection.[figure1] (Supported by NIH (HD30146 (NCMRR/NICHD) [amp] EB00856 (NIBIB[amp]NINDS) (JRW).)