Authors :
Presenting Author: Hayoung Ahn, BA – University of California, Los Angeles
Yaretson Carmenate, B.S. – University of California, Los Angeles - David Geffen School of Medicine
Alexander Weil, MD – Centre Hospitalier Universitaire Sainte-Justine
George Ibrahim, MD, PhD – Hospital for Sick Children
Evan Lewis, MD – Hospital for Sick Children
Aris Hadjinicolaou, MD – CHU Sainte-Justine
Aria Fallah, MD, MSc, MBA – Department of Neurosurgery, UCLA Medical Center, David Geffen School of Medicine
Shaun A. Hussain, MD, MS – Division of Pediatric Neurology, Department of Pediatrics, UCLA Mattel Children's Hospital, David Geffen School of Medicine
Rationale:
Predictors of seizure-freedom following hemispherectomy were evaluated in a large multicenter international cohort study, which yielded the Hemispherectomy Outcome Prediction Scale (HOPS; Weil et al, 2021) and specifically identified history of infantile spasms as a risk factor for seizure recurrence. In this study we set out to evaluate predictors of seizure recurrence among subjects with history of infantile spasms.Methods:
Data from the HOPS study were re-evaluated in a post-hoc analysis. Predictors of post-hemispherectomy seizure recurrence were evaluated with the Kaplan-Meier procedure as well as bivariate and multivariate Cox proportional hazards regression. Results:
We identified 187 children with history of infantile spasms and complete data with respect to pre-surgical MRI, positron-emission tomography (PET), and EEG. 44 (24%) subjects exhibited seizure relapse with median latency of 9 months (IQR 3 – 36). In sequential univariate analyses, latency to seizure recurrence was associated with presence of bilateral PET hypometabolism (HR = 3.2, 95% CI 1.3 – 7.5, p = 0.009), age of first seizure < 6 months (HR 6.7, 95% CI 1.6 – 27.5, p = 0.009), female sex (HR = 1.9, 95% CI 1.0 – 3.5, p = 0.04), and bilateral interictal EEG abnormalities (HR 2.2, 95% CI 1.1 – 4.5, p = 0.03). All four factors were retained in a final multivariable model: presence of bilateral PET hypometabolism (HR = 3.1, 95% CI 1.2 – 8.3, p = 0.02), age of first seizure < 6 months (HR 4.9, 95% CI 1.2 – 20.7, p = 0.03), female sex (HR = 2.2, 95% CI 1.1 – 4.2, p = 0.02), and bilateral interictal EEG abnormalities (HR 1.8, 95% CI 0.9 – 3.8, p = 0.1 [trend]). Of note, contralateral or normal MRI findings were not associated with seizure recurrence on a univariate or multivariate basis.
Conclusions:
This study suggests that among children with history of infantile spasms, risk of seizure recurrence after hemispherectomy is driven by age at first seizure and contralateral abnormalities on interictal EEG and PET imaging. This is expected in that (1) contralateral EEG/PET findings likely map to unresected structural abnormalities with epileptogenic potential, and (2) longer duration of infantile spasms has been linked to poor response to both surgical and pharmacologic treatment. However, the lack of association of recurrence with contralateral or normal MRI abnormalities is surprising as MRI is often regarded as the single most important test to identify candidates for epilepsy surgery. We suspect this lack of association may reflect the presence of subtle focal cortical dysplasia (especially ILAE type 1) that may escape detection on presurgical MRI. This further suggests that interictal PET should be a mandatory test for children with refractory infantile spasms, even in the setting of normal MRI and symmetric EEG.
Funding:
This study was accomplished with support from the John C. Hench Foundation.