Presurgical language localization with visual naming associated ECoG high‐ gamma modulation in pediatric drug‐resistant epilepsy

Abstract

Objective This prospective study compared pre-surgical language localization with visual naming associated high-γ modulation (HGM) and conventional electrical cortical stimulation (ECS) in children with intracranial electrodes. Methods Drug-resistant epilepsy patients undergoing intracranial monitoring were included if able to name pictures. ECoG signals were recorded during picture naming (overt and covert) and quiet baseline. For each electrode the likelihood of high-γ (70–116 Hz) power modulation during naming task relative to the baseline was estimated. Electrodes with significant HGM were plotted on a 3D cortical surface model. Sensitivity, specificity, and accuracy were calculated compared to clinical ECS. Results Seventeen patients with mean age of 11.3 years (range: 4–19) were included. In patients with left hemisphere electrodes (n=10), HGM during overt naming showed high specificity (0.81, 95% CI 0.78–0.85), and accuracy (0.71, 95% CI 0.66–0.75, p<0.001), but modest sensitivity (0.47) when ECS interference with naming (aphasia or paraphasic errors) and/or oral-motor function was regarded as the gold standard. Similar results were reproduced by comparing covert naming associated HGM with ECS naming sites. With right hemisphere electrodes (n=7), no ECS naming deficits were seen without interference with oral motor function. HGM mapping showed a high specificity (0.81, 95% CI 0.78–0.84), and accuracy (0.76, 95% CI 0.71–0.81, p=0.006), but modest sensitivity (0.44) compared to ECS interference with oral motor function. Naming-associated ECoG HGM was consistently observed over Broca’s area (left posterior inferior frontal gyrus), bilateral oral/facial motor cortex, and sometimes over temporal pole. Significance This study supports the use of ECoG HGM mapping in children where adverse events preclude ECS, or as a screening method to prioritize electrodes for ECS testing.

Electrocorticographic high‐gamma modulation with passive listening paradigm for pediatric extraoperative language mapping

“…The value of this study is that it demonstrates the feasibility of presurgical language mapping using a passive story‐listening task that can be performed in children who cannot otherwise cooperate with conventional language tasks requiring sustained active engagement. Secondly, the incorporation of additional language tasks in a modular fashion can further improve the accuracy of language localization with HGM . This study contributes toward the emerging evidence for clinical utility of HGM mapping, which is time efficient and avoids the risks of ESM‐induced ADs and seizures.…”

“…For all patients with left hemisphere electrodes included in this study, we also recorded HGM during a visual naming task, whose details and results were published earlier . We performed a post hoc analysis by scoring electrodes as HGM+ if they showed significant HGM with either the naming or listening task.…”

“…For all patients with left hemisphere electrodes included in this study, we also recorded HGM during a visual naming task, whose details and results were published earlier. 7 We performed a post hoc analysis by scoring electrodes as HGM+ if they showed significant HGM with either the naming or listening task. On comparing such electrodes with either aphasic or sensorimotor naming dysfunction during ESM, the specificity was similar (0.85, 95% CI = 0.81-0.88), but the sensitivity (0.69, 95% CI = 0.62-0.76), accuracy (0.80, 95% CI = 0.75-0.84), and DOR (13.61, 95% CI = 6.99-26.47) improved substantially (P < .0001, Table 3).…”

“…Specifically, modulation in the high‐gamma frequency band, usually defined as ≥50 Hz, has been shown to correlate well with task‐related neuronal firing rates and blood oxygen level–dependent (BOLD) responses . While mapping with high‐gamma modulation (HGM) potentially addresses concerns about electrical stimulation, the tasks most often used for language mapping with these modalities require sustained active patient engagement under rather challenging clinical conditions . In this prospective study, we compared the topography of HGM during a passive story‐listening task requiring negligible patient cooperation, with the conventional ESM‐induced naming dysfunction, for extraoperative language localization in childhood‐onset DRE.…”

Development of information sharing in language neocortex in childhood‐onset drug‐resistant epilepsy

“…2,7 The onsets of picture displays, story, and noise periods were synchronized to the ECoG signals as digital pulses input on separate channels through a trigger box (g.tec medical engineering).…”