Epileptic discharges are classified as generalized paroxysmal fast activity with low expert agreement: findings from an international survey
- 1Localization Laboratory, Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston,
Abstract
ObjectiveThe current International League Against Epilepsy (ILAE) guidelines for Lennox-Gastaut syndrome (LGS) mandate the presence of generalized paroxysmal fast activity (GPFA) on EEG. However, GPFA is not necessarily restricted to LGS and has been described in, among others, idiopathic generalized epilepsies. A clear definition for GPFA is currently lacking, hampering research into its utility as a diagnostic or treatment biomarker. Here, we assessed expert agreement in the interpretation of GPFA to explore feasibility of a consensus-based definition.
MethodsWe internationally distributed a two-part survey on GPFA to EEG experts. First, participants completed thirteen questions gauging their preferred clinical and EEG criteria for GPFA, including duration, frequency, amplitude and topography. Second, participants classified the presence versus absence of GPFA in eleven EEG clips, while blinded to clinical context, from patients with LGS, other epilepsies, and physiological variants.
Results162 respondents, predominantly from North America and Europe, completed the survey. 87% considered GPFA to also occur in epilepsies other than LGS. Considerable heterogeneity was present on defining duration, spectral frequency, amplitude and topographic distribution of GPFA. Particularly poor agreement was seen for lower limits of duration and frequency, with no single response option receiving a majority consensus (36% and 30% agreement, respectively). Similarly, the degree of agreement on interpretations was highly variable across real-world EEG clips.
SignificanceMarked discrepancies exist in the EEG identification and clinical interpretation of GPFA, undermining its utility as a potential biomarker in research and clinical trials of LGS and other epilepsies. The findings also highlight the need to establish a consensus-based and eventually evidence-informed definition to formally operationalize the clinical and EEG criteria for GPFA.
Key pointsO_LIGeneralized paroxysmal fast activity (GPFA) is variably defined in the literature, limiting its utility as a diagnostic or treatment biomarker C_LIO_LIIn this international survey (n = 162 respondents, 25 countries) we found limited agreement on GPFAs defining features and on interpretation of fast activity on EEG clips C_LIO_LI87% of respondents considered GPFA to occur in epilepsies other than Lennox-Gastaut syndrome C_LIO_LIPending further elucidation of the pathophysiology underlying GPFA or its computational characterization (i.e., to inform a biologically-or evidence-based definition), we underscore the need for an interim consensus-based definition C_LI
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BibTeX
@misc{kampman2026epileptic,
title = {{Epileptic discharges are classified as generalized paroxysmal fast activity with low expert agreement: findings from an international survey}},
author = {S. L. Kampman and A. E. Warren and I. Tokatly Latzer and M. Stamm and J. D. Rolston and J. S. Archer and S. Tobochnik and J. M. Peters},
howpublished = {medRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.18.26362075},
url = {https://www.medrxiv.org/content/10.64898/2026.09.18.26362075v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Epileptic discharges are classified as generalized paroxysmal fast activity with low expert agreement: findings from an international survey
AU - S. L. Kampman
AU - A. E. Warren
AU - I. Tokatly Latzer
AU - M. Stamm
AU - J. D. Rolston
AU - J. S. Archer
AU - S. Tobochnik
AU - J. M. Peters
PY - 2026
DA - 2026/09/18
PB - medRxiv
DO - 10.64898/2026.09.18.26362075
UR - https://www.medrxiv.org/content/10.64898/2026.09.18.26362075v1
AB - ObjectiveThe current International League Against Epilepsy (ILAE) guidelines for Lennox-Gastaut syndrome (LGS) mandate the presence of generalized paroxysmal fast activity (GPFA) on EEG. However, GPFA is not necessarily restricted to LGS and has been described in, among others, idiopathic generalized epilepsies. A clear definition for GPFA is currently lacking, hampering research into its utility as a diagnostic or treatment biomarker. Here, we assessed expert agreement in the interpretation of GPFA to explore feasibility of a consensus-based definition. MethodsWe internationally distributed a two-part survey on GPFA to EEG experts. First, participants completed thirteen questions gauging their preferred clinical and EEG criteria for GPFA, including duration, frequency, amplitude and topography. Second, participants classified the presence versus absence of GPFA in eleven EEG clips, while blinded to clinical context, from patients with LGS, other epilepsies, and physiological variants. Results162 respondents, predominantly from North America and Europe, completed the survey. 87% considered GPFA to also occur in epilepsies other than LGS. Considerable heterogeneity was present on defining duration, spectral frequency, amplitude and topographic distribution of GPFA. Particularly poor agreement was seen for lower limits of duration and frequency, with no single response option receiving a majority consensus (36% and 30% agreement, respectively). Similarly, the degree of agreement on interpretations was highly variable across real-world EEG clips. SignificanceMarked discrepancies exist in the EEG identification and clinical interpretation of GPFA, undermining its utility as a potential biomarker in research and clinical trials of LGS and other epilepsies. The findings also highlight the need to establish a consensus-based and eventually evidence-informed definition to formally operationalize the clinical and EEG criteria for GPFA. Key pointsO_LIGeneralized paroxysmal fast activity (GPFA) is variably defined in the literature, limiting its utility as a diagnostic or treatment biomarker C_LIO_LIIn this international survey (n = 162 respondents, 25 countries) we found limited agreement on GPFAs defining features and on interpretation of fast activity on EEG clips C_LIO_LI87% of respondents considered GPFA to occur in epilepsies other than Lennox-Gastaut syndrome C_LIO_LIPending further elucidation of the pathophysiology underlying GPFA or its computational characterization (i.e., to inform a biologically-or evidence-based definition), we underscore the need for an interim consensus-based definition C_LI
ER -