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. 2022 Nov 23:13:1030118.
doi: 10.3389/fneur.2022.1030118. eCollection 2022.

Estimated EEG functional connectivity and aperiodic component induced by vagal nerve stimulation in patients with drug-resistant epilepsy

Roberta Coa  1 , Simone Maurizio La Cava  2 , Giulia Baldazzi  2   3 , Lorenzo Polizzi  4 , Giovanni Pinna  5 , Carlo Conti  5 , Giovanni Defazio  4   6 , Danilo Pani  2 , Monica Puligheddu  4   6
Affiliations

Estimated EEG functional connectivity and aperiodic component induced by vagal nerve stimulation in patients with drug-resistant epilepsy

Roberta Coa et al. Front Neurol. .

Abstract

Background: Vagal nerve stimulation (VNS) improves seizure frequency and quality of life in patients with drug-resistant epilepsy (DRE), although the exact mechanism is not fully understood. Previous studies have evaluated the effect of VNS on functional connectivity using the phase lag index (PLI), but none has analyzed its effect on EEG aperiodic parameters (offset and exponent), which are highly conserved and related to physiological functions.

Objective: This study aimed to evaluate the effect of VNS on PLI and aperiodic parameters and infer whether these changes correlate with clinical responses in subjects with DRE.

Materials and methods: PLI, exponent, and offset were derived for each epoch (and each frequency band for PLI), on scalp-derived 64-channel EEG traces of 10 subjects with DRE, recorded before and 1 year after VNS. PLI, exponent, and offset were compared before and after VNS for each patient on a global basis, individual scalp regions, and channels and separately in responders and non-responders. A correlation analysis was performed between global changes in PLI and aperiodic parameters and clinical response.

Results: PLI (global and regional) decreased after VNS for gamma and delta bands and increased for an alpha band in responders, but it was not modified in non-responders. Aperiodic parameters after VNS showed an opposite trend in responders vs. non-responders: both were reduced in responders after VNS, but they were increased in non-responders. Changes in aperiodic parameters correlated with the clinical response.

Conclusion: This study explored the action of VNS therapy from a new perspective and identified EEG aperiodic parameters as a new and promising method to analyze the efficacy of neuromodulation.

Keywords: EEG; aperiodic component; drug-resistant epilepsy (DRE); functional connectivity (Fc); vagus nerve stimulation (VNS).

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Conflict of interest statement

Unrelated to this study, in the past 3 years, Author RC received support for congress attendance from a distributor of VNS therapy and Author MP had a consulting contract with Livanova, USA. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
Effect on VNS. Representation of the most relevant post- vs. pre-VNS PLI changes in absolute terms (cut-off: 10%) in responder and non-responder patients. Red lines denote the increased PLI after VNS; blue lines represent the decreased PLI after VNS. Statistically significant channels are represented as red or light blue dots depending on whether the trend increases or decreases.
Figure 2
Figure 2
Effects on aperiodic components. Visual representation of the change in the exponent and offset parameters after VNS in responders and non-responders. Colors represent the trend of change: dark red stands for increase after VNS and light yellow for decrease. Statistically significant channels are highlighted as red or white dots depending on whether the trend is increasing or decreasing.
Figure 3
Figure 3
Data distributions of offset, exponent, and PLI parameters for both responders (R) and non-responders (NR) patients in the global scale analysis. Statistically significant distributions are represented by boxplots in terms of median value (red line) and 75th and 25th percentiles (upper and lower limits of the blue box, respectively). In this representation, black whiskers and red crosses identify the distribution extrema and the outliers, respectively. *p < 0.05, **p < 0.01, ***p < 0.001.
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References

    1. Yamamoto T. Vagus nerve stimulation therapy: indications, programing, and outcomes. Neurol Med Chir. (2015) 55:407–15. 10.2176/nmc.ra.2014-0405 - DOI - PMC - PubMed
    1. Giordano F, Zicca A, Barba C, Guerrini R, Genitori L. Vagus nerve stimulation: surgical technique of implantation and revision and related morbidity. Epilepsia. (2017) 58:85–90. 10.1111/epi.13678 - DOI - PubMed
    1. Marras CE, Chiesa V, Benedictis A De, Franzini A, Rizzi M, Villani F, et al. . Vagus nerve stimulation in refractory epilepsy: new indications and outcome assessment. Epilepsy Behav. (2013) 28:374–8. 10.1016/j.yebeh.2013.05.021 - DOI - PubMed
    1. Wasade VS, Schultz L, Mohanarangan K, Gaddam A, Schwalb JM, Spanaki-Varelas M. Long-Term Seizure Psychosocial Outcomes of Vagus Nerve Stimulation for Intractable Epilepsy. (2015). Available online at: https://ac.els-cdn.com/S1525505015005533/1-s2.0-S1525505015005533-main.p... (accessed March 11, 2018). - PubMed
    1. Biggio F, Gorini G, Utzeri C, Olla P, Marrosu F, Mocchetti I, et al. . Chronic vagus nerve stimulation induces neuronal plasticity in the rat hippocampus. Int J Neuropsychopharmacol. (2009) 12:1209–21. 10.1017/S1461145709000200 - DOI - PMC - PubMed