Real-time functional mapping: potential tool for improving language outcome in pediatric epilepsy surgery

Abstract

<jats:p>Accurate language localization expands surgical treatment options for epilepsy patients and reduces the risk of postsurgery language deficits. Electrical cortical stimulation mapping (ESM) is considered to be the clinical gold standard for language localization. While ESM affords clinically valuable results, it can be poorly tolerated by children, requires active participation and compliance, carries a risk of inducing seizures, is highly time consuming, and is labor intensive. Given these limitations, alternative and/or complementary functional localization methods such as analysis of electrocorticographic (ECoG) activity in high gamma frequency band in real time are needed to precisely identify eloquent cortex in children.</jats:p> <jats:p>In this case report, the authors examined 1) the use of real-time functional mapping (RTFM) for language localization in a high gamma frequency band derived from ECoG to guide surgery in an epileptic pediatric patient and 2) the relationship of RTFM mapping results to postsurgical language outcomes. The authors found that RTFM demonstrated relatively high sensitivity (75%) and high specificity (90%) when compared with ESM in a “next-neighbor” analysis. While overlapping with ESM in the superior temporal region, RTFM showed a few other areas of activation related to expressive language function, areas that were eventually resected during the surgery. The authors speculate that this resection may be associated with observed postsurgical expressive language deficits. With additional validation in more subjects, this finding would suggest that surgical planning and associated assessment of the risk/benefit ratio would benefit from information provided by RTFM mapping.</jats:p>

Deep Learning provides exceptional accuracy to ECoG-based Functional Language Mapping for epilepsy surgery

“…A baseline recording of the cortical activity was first acquired to capture the "resting-state" neuronal activity. Following the baseline recording step, paradigms similar to those employed in ESM or fMRI were used to record the taskrelated ECoG signal for functional mapping 25 . Figure 2 shows one such paradigm, mimicking details of the experimental setup for the language comprehension task that we used.…”

Automatic response assessment in regions of language cortex in epilepsy patients using ECoG-based functional mapping and machine learning

“…Alternate 30 second blocks of ECoG data during "control" and "active" conditions are recorded continuously at a fixed sampling rate of 1200 Hz. For the language comprehension task, the active condition implies listening to a story, while the control task involves listening to broadband noise [11]. Another associated paradigm is the reading comprehension task where the subject reads sentences from a screen, and replies with a "True" or "False" response.…”

Electrocorticography-Based Real-Time Functional Mapping for Pediatric Epilepsy Surgery

“…1) was proposed by Schalk et al 22,23 This approach extended beyond off-line processing and involved a real-time ECoG signal analysis for functional mapping (realtime functional mapping or RTFM). This approach has created a potential for instant visualization of task-associated changes in ECoG signal, which may be used in clinical settings, either directly at the patient's bed-side 24,25 (►Fig. 2A,B) or intraoperatively 26 (►Fig.…”

“…The patient is instructed to overtly name each presented object. The objects on the screen are presented in color 25 or as black and white drawings. 31,40,75 In case the patient is unable to immediately name the item, he/ she is instructed to say "pass."…”