Scale-Free Analysis of Intraoperative ECoG During Awake Craniotomy for Glioma

Abstract

BackgroundElectrocorticography (ECoG) has been utilized in many epilepsy cases however, the use of this technique for evaluating electrophysiological changes within tumoral zones is spare. Nonetheless, epileptic activities seem to arise from the neocortex surrounding the gliomas suggesting a link between epileptogenesis and glioma cell infiltration in the peritumoral area. The purpose of this study was to implement novel scale-free measures to assess how cortical physiology is altered by the presence of an invasive brain tumor.MethodsTwelve patients undergoing an awake craniotomy for resection of a supratentorial glioma were included. ECoG data over the main tumor and the exposed surroundings was acquired intra-operatively just prior to tumor resection. Six of the patients presented with seizures and had data acquired both in the awake and anesthetic state. The corresponding anatomical location of each electrode in relation to the macroscopically-detectable tumor was recorded using the neuronavigation system based on structural anatomical images obtained pre-operatively. The electrodes were classified into tumoral, healthy or peritumoral based on the macroscopically detectable tumoral tissue from the pre-operative structural MRI.ResultsThe electrodes overlying the tumoral tissue revealed higher power law exponent (PLE) values across tumoral area compared to the surrounding tissues. The difference between the awake and anesthetic states was significant in the tumoral and healthy tissue (p < 0.05) but not in the peritumoral tissue. The absence of a significant PLE reduction in the peritumoral tissue from the anesthetic to the awake state could be considered as an index of the presence or absence of infiltration of tumor cells into the peritumoral tissue.ConclusionsThe current study portrays for the first time distinct power law exponent features in the tumoral tissue, which could provide a potential novel electrophysiological marker in the future. The distinct features seen in the peritumoral tissue of gliomas seem to indicate the area where both the onset of epileptiform activity and the tumor infiltration take place.

Age-related changes in “cortical” 1/f dynamics are linked to cardiac activity

“…However, our results suggest that cardiac activity remains in EEG signals even after doing an ICA (see Figure 1CEF). (He et al, 2010;Penzel et al, 2003)) and disorders like Parkinson's disease and epilepsy (Ansakorpi, 2002;Ghinda et al, 2021;Haapaniemi, 2001;Mostile et al, 2019).…”

“…Cardiac and cortical recordings of aperiodic electrophysiological signals are related to age (Beckers et al, 2006; Voytek et al, 2015), cognitive states (eg. awake vs. sleep; (He et al, 2010; Penzel et al, 2003)) and disorders such as Parkinson’s disease and epilepsy (Ansakorpi, 2002; Ghinda et al, 2021; Haapaniemi, 2001; Mostile et al, 2019). In the present study we investigated the question whether age-related changes in neural and cardiac aperiodic activity are modulated independently or if “cortically” measured aperiodic activity is explained by cardiac activity captured by surface electrodes (via volume conduction).…”

“…Similar caveats adhere to other findings of functional modulations in aperiodic signals in cognitive states (eg. awake vs. sleep; (He et al, 2010; Penzel et al, 2003)) and disorders like Parkinson’s disease and epilepsy (Ansakorpi, 2002; Ghinda et al, 2021; Haapaniemi, 2001; Mostile et al, 2019). While the present analysis focuses on aperiodic activity, our results might also translate to older findings focusing on “presumably” periodic neural activity in canonical frequency bands (e.g.…”

“…Several studies have shown that aperiodic neural activity is meaningfully modulated by various factors, such as age (Voytek et al, 2015), cognitive state (e.g. awake vs. sleep; (He et al, 2010)) and disorders like Parkinson's disease and epilepsy (Ghinda et al, 2021;Mostile et al, 2019).…”

Clinical neuroscience and neurotechnology: An amazing symbiosis

“…This is the case for brain tumor surgery. Epileptic activity often arises in patients with gliomas ( Ghinda et al., 2021 ; Saito et al., 2018 ), thus some patients with brain tumors undergo intraoperative ECoG monitoring, typically during awake craniotomy ( Goldstein and Feyissa, 2018 ; Yao et al., 2018 ). The presence of high-frequency oscillations in the ECoG signal seems to be a spatial marker of the epileptogenic zones in brain tumor-related epilepsy ( Feyissa et al., 2018 ; Peng et al., 2021 ; Quitadamo et al., 2018 ; Sun et al., 2022 ; van Klink et al., 2021 ; Zhang et al., 2021 ), even though there is some disagreement between researchers ( Robertson et al., 2019 ; Zhu et al., 2022 ).…”