Predictors of Relapse of Infantile Epileptic Spasms Syndrome After Initial Response to Vigabatrin
Abstract number :
1.387
Submission category :
7. Anti-seizure Medications / 7C. Cohort Studies
Year :
2025
Submission ID :
642
Source :
www.aesnet.org
Presentation date :
12/6/2025 12:00:00 AM
Published date :
Authors :
Presenting Author: Yaretson Carmenate, B.S. – University of California, Los Angeles - David Geffen School of Medicine
Hayoung Ahn, BA – University of California, Los Angeles
Haley Peters, BS – University of California, Los Angeles
Hiroki Nariai, MD, PhD, MS – Department of Pediatrics, Division of Pediatric Neurology, David Geffen School of Medicine at the University of California, Los Angeles, California, USA
Rajsekar Rajaraman, MD – David Geffen School of Medicine; UCLA Mattel Children’s Hospital
Shaun A. Hussain, MD, MS – Division of Pediatric Neurology, Department of Pediatrics, UCLA Mattel Children's Hospital, David Geffen School of Medicine
Rationale: Vigabatrin is an effective first-line treatment for Infantile Epileptic Spasms Syndrome (IESS). However, relapse after initial response remains a frequent and poorly understood clinical challenge. Existing literature provides limited guidance on optimal VGB dosing, treatment duration, and risk stratification for relapse. We aimed to fill this knowledge gap by identifying clinical and treatment-related predictors of relapse among patients with IESS who initially responded to VGB.
Methods: We conducted a retrospective cohort study of infants diagnosed with IESS at UCLA between 2004 and 2024 who achieved electroclinical response within 30 days of VGB initiation and sustained remission for > 30 days. Clinical features, treatment characteristics, and outcomes were extracted from the electronic medical record. Time to relapse was analyzed using the Kaplan-Meier procedure and Cox proportional hazards regression. Candidate predictors included VGB dose and duration, latency to VGB treatment, etiology, use of dual therapy (i.e. concomitant ACTH or prednisolone), and presence of other seizure-types at IESS onset.
Results: Among 164 patients with initial response to VGB, 63 (38.4%) relapsed, at a median interval of 7.5 months (IQR: 2.4–18.0) after response. Forty-two of these 63 (66.7%) relapsed while still receiving VGB. In multivariable Cox proportional hazards regression, shorter latency to relapse was associated with time from IESS onset to VGB treatment (HR 1.04 per month delay, p = .004), history of relapse prior to VGB treatment (HR 1.87, p = .047), presence of non-spasm seizures at IESS onset (HR 1.81, p = .037), and known etiology (HR: 3.03, p = .018). VGB dosing showed a non-linear relationship; relapse rates were lowest in the 100–149 mg/kg/day group (31.0%) compared to lower (53.1%) and higher (42.2%) dosing groups (p = .039, Chi-square). Concomitant hormonal therapy was not associated with reduced relapse rates. In a severely underpowered analysis using proportional hazards regression with time-varying covariates, after adjustment for the aforementioned significant covariates, the point estimate of the HR for ongoing VGB treatment was 0.73 (95%CI 0.37 – 1.43, p = .355), suggesting that continued vigabatrin may reduce the risk of IESS relapse.
Conclusions: These data suggest—but far from confirm—that continued vigabatrin (100 to 149 mg/kg/day) may protect against IESS relapse. Vigabatrin—or any potential relapse prevention strategy—is most needed for patients with known etiology, other seizure-types, delayed initiation of vigabatrin, and history of prior IESS relapse. Further prospective study is needed to validate observations described in this study.
Funding: This study was accomplished with support from the John C. Hench Foundation
Anti-seizure Medications