Relative Source Power: A novel method for localizing epileptiform EEG discharges

Michael Scherg; Reinhard Schulz; Patrick Berg; Jae-Hyun Cho; Harald Bornfleth; Mustafa A Kural; Friedrich G Woermann; Christian G Bien; Sándor Beniczky

doi:10.1016/j.clinph.2021.10.005

Relative Source Power: A novel method for localizing epileptiform EEG discharges

Michael Scherg^*, Reinhard Schulz, Patrick Berg, Jae-Hyun Cho, Harald Bornfleth, Mustafa A Kural, Friedrich G Woermann, Christian G Bien, Sándor Beniczky

^*Corresponding author af dette arbejde

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Publikation: Bidrag til tidsskrift › Artikel › Forskning › peer review

Abstract

OBJECTIVE: To validate relative source power (RSP) imaging of extratemporal interictal epileptiform discharges (IEDs).

METHODS: The accuracy of RSP was validated in a cohort of patients with extratemporal focal epilepsy and a confined epileptogenic lesion (<19 cm3) using distance to the lesion, concordance with resected area and postoperative outcome. Performance was compared with three conventional methods: voltage maps, equivalent current dipole and a distributed source model.

RESULTS: Thirty-three of 41 consecutive patients (80%) had IED averages suitable for analysis. While the peak negativity in voltage maps localized above the epileptogenic lesion only in 18 cases, RSP-maps matched in 29 cases (88%, p < 0.0026). Source localization showed a median distance of 9.8 mm from the lesion. Source-regions with 20 mm radius included 98% of all source-to-lesion distances. In the 21 surgical cases, outcome showed a sensitivity of 82.35% and specificity of 50% without significant differences between the three source imaging methods.

CONCLUSIONS: RSP-maps provide a rapid, intuitive and more accurate source estimation than voltage maps. At sublobar level, RSP localizes with an accuracy similar to conventional methods and results of previous studies.

SIGNIFICANCE: The definition of a source region with 20 mm radius helps in guiding further exploration in extratemporal focal epilepsy.

Originalsprog	Engelsk
Sider (fra-til)	9-19
Antal sider	11
Tidsskrift	Clinical Neurophysiology
Vol/bind	133
Tidlig onlinedato	29 okt. 2021
DOI	https://doi.org/10.1016/j.clinph.2021.10.005
Status	Udgivet - jan. 2022

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10.1016/j.clinph.2021.10.005

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title = "Relative Source Power: A novel method for localizing epileptiform EEG discharges",

abstract = "OBJECTIVE: To validate relative source power (RSP) imaging of extratemporal interictal epileptiform discharges (IEDs).METHODS: The accuracy of RSP was validated in a cohort of patients with extratemporal focal epilepsy and a confined epileptogenic lesion (<19 cm3) using distance to the lesion, concordance with resected area and postoperative outcome. Performance was compared with three conventional methods: voltage maps, equivalent current dipole and a distributed source model.RESULTS: Thirty-three of 41 consecutive patients (80\%) had IED averages suitable for analysis. While the peak negativity in voltage maps localized above the epileptogenic lesion only in 18 cases, RSP-maps matched in 29 cases (88\%, p < 0.0026). Source localization showed a median distance of 9.8 mm from the lesion. Source-regions with 20 mm radius included 98\% of all source-to-lesion distances. In the 21 surgical cases, outcome showed a sensitivity of 82.35\% and specificity of 50\% without significant differences between the three source imaging methods.CONCLUSIONS: RSP-maps provide a rapid, intuitive and more accurate source estimation than voltage maps. At sublobar level, RSP localizes with an accuracy similar to conventional methods and results of previous studies.SIGNIFICANCE: The definition of a source region with 20 mm radius helps in guiding further exploration in extratemporal focal epilepsy.",

keywords = "Epilepsy surgery, Extratemporal lesions, Interictal discharge, Source imaging, Source localization, EEG mapping",

author = "Michael Scherg and Reinhard Schulz and Patrick Berg and Jae-Hyun Cho and Harald Bornfleth and Kural, \{Mustafa A\} and Woermann, \{Friedrich G\} and Bien, \{Christian G\} and S{\'a}ndor Beniczky",

year = "2022",

month = jan,

doi = "10.1016/j.clinph.2021.10.005",

language = "English",

volume = "133",

pages = "9--19",

journal = "Clinical Neurophysiology",

issn = "1388-2457",

publisher = "Elsevier Ireland Ltd",

}

TY - JOUR

T1 - Relative Source Power

T2 - A novel method for localizing epileptiform EEG discharges

AU - Scherg, Michael

AU - Schulz, Reinhard

AU - Berg, Patrick

AU - Cho, Jae-Hyun

AU - Bornfleth, Harald

AU - Kural, Mustafa A

AU - Woermann, Friedrich G

AU - Bien, Christian G

AU - Beniczky, Sándor

PY - 2022/1

Y1 - 2022/1

N2 - OBJECTIVE: To validate relative source power (RSP) imaging of extratemporal interictal epileptiform discharges (IEDs).METHODS: The accuracy of RSP was validated in a cohort of patients with extratemporal focal epilepsy and a confined epileptogenic lesion (<19 cm3) using distance to the lesion, concordance with resected area and postoperative outcome. Performance was compared with three conventional methods: voltage maps, equivalent current dipole and a distributed source model.RESULTS: Thirty-three of 41 consecutive patients (80%) had IED averages suitable for analysis. While the peak negativity in voltage maps localized above the epileptogenic lesion only in 18 cases, RSP-maps matched in 29 cases (88%, p < 0.0026). Source localization showed a median distance of 9.8 mm from the lesion. Source-regions with 20 mm radius included 98% of all source-to-lesion distances. In the 21 surgical cases, outcome showed a sensitivity of 82.35% and specificity of 50% without significant differences between the three source imaging methods.CONCLUSIONS: RSP-maps provide a rapid, intuitive and more accurate source estimation than voltage maps. At sublobar level, RSP localizes with an accuracy similar to conventional methods and results of previous studies.SIGNIFICANCE: The definition of a source region with 20 mm radius helps in guiding further exploration in extratemporal focal epilepsy.

AB - OBJECTIVE: To validate relative source power (RSP) imaging of extratemporal interictal epileptiform discharges (IEDs).METHODS: The accuracy of RSP was validated in a cohort of patients with extratemporal focal epilepsy and a confined epileptogenic lesion (<19 cm3) using distance to the lesion, concordance with resected area and postoperative outcome. Performance was compared with three conventional methods: voltage maps, equivalent current dipole and a distributed source model.RESULTS: Thirty-three of 41 consecutive patients (80%) had IED averages suitable for analysis. While the peak negativity in voltage maps localized above the epileptogenic lesion only in 18 cases, RSP-maps matched in 29 cases (88%, p < 0.0026). Source localization showed a median distance of 9.8 mm from the lesion. Source-regions with 20 mm radius included 98% of all source-to-lesion distances. In the 21 surgical cases, outcome showed a sensitivity of 82.35% and specificity of 50% without significant differences between the three source imaging methods.CONCLUSIONS: RSP-maps provide a rapid, intuitive and more accurate source estimation than voltage maps. At sublobar level, RSP localizes with an accuracy similar to conventional methods and results of previous studies.SIGNIFICANCE: The definition of a source region with 20 mm radius helps in guiding further exploration in extratemporal focal epilepsy.

KW - Epilepsy surgery

KW - Extratemporal lesions

KW - Interictal discharge

KW - Source imaging

KW - Source localization

KW - EEG mapping

U2 - 10.1016/j.clinph.2021.10.005

DO - 10.1016/j.clinph.2021.10.005

M3 - Article

C2 - 34788717

SN - 1388-2457

VL - 133

SP - 9

EP - 19

JO - Clinical Neurophysiology

JF - Clinical Neurophysiology

ER -

Relative Source Power: A novel method for localizing epileptiform EEG discharges

Abstract

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