Temporal evolution of EEG hallmarks in childhood Lennox-Gastaut syndrome
Luca Bergonzini1, Susan Harvey2, Krishna Das3
1Department of Clinical Neurophysiology, Great Ormond Street Hospital for Children, London, United Kingdom; IRCCS Istituto delle Scienze Neurologiche di Bologna, U.O.C. Neuropsichiatria dell'età pediatrica, Full Member of the ERN EpiCare, Bologna, Italy; Department of Medical and Surgical Sciences (DIMEC), Alma Mater Studiorum - University of Bologna, Bologna, Italy.
Purpose:
The temporal development of generalized paroxysmal fast activity (GPFA) and slow spike-and-wave complexes in childhood Lennox-Gastaut syndrome (LGS) remains poorly characterized. This study mapped the emergence and longitudinal evolution of these EEG hallmarks in a real-world LGS cohort.
Methods:
This retrospective observational cohort study was conducted at a tertiary pediatric neurophysiology and neurology center. Patients aged 1-18 years fulfilling current International League Against Epilepsy criteria for LGS were identified through local databases. All available sleep video-EEG recordings before November 2024 were reviewed; clinical features, EEG findings, and comorbidities were collected at each recording. Statistical significance was set at p < 0.05.
Results:
We reviewed 234 EEGs from 51 patients (75% male). Median age at first EEG was 5 years. GPFA emerged later than slow spike-and-wave (mean age: 9.6 vs 8.3 years, p = 0.002), with non-parametric analysis confirming a significant difference in age at first detection (p = 0.004). Median age at epilepsy onset was 1.1 years, while all clinical and EEG criteria for LGS were met at a median age of 10.9 years.
Conclusion:
EEG hallmarks of LGS emerged progressively during childhood, with slow spike-and-wave preceding GPFA during sleep. Following early clinical manifestations, a prolonged developmental phase may precede full electroclinical expression of LGS, with implications for early diagnosis and longitudinal EEG surveillance.
