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Published on: July 8, 2025
Late-onset epileptic spasms: presentation, aetiology and outcome
Sameer Dal1,2, Emma Macdonald-Laurs1,2,3, Simone Mandelstam4
1Department of Neurology, The Royal Children's Hospital, Melbourne, Victoria 3052, Australia.
Brain Communications
|July 3, 2026
Summary
Late-onset epileptic spasms (LOES) are often misdiagnosed, but prompt recognition improves outcomes. Brain malformations are the main cause, and unilateral cases respond best to epilepsy surgery.
Area of Science:
- Neurology
- Pediatric Neurology
- Epileptology
Background:
- Late-onset epileptic spasms (LOES) are epileptic spasms (ES) starting after 12 months, often misdiagnosed and with unclear links to infantile spasms.
- Previous studies on LOES cohorts were small, frequently reporting 'cryptogenic' (unknown) causes.
Purpose of the Study:
- To investigate presentations, causes, treatment responses, and outcomes in a large cohort of children with LOES.
- To evaluate LOES using modern neuroimaging and genomic testing.
Main Methods:
- Retrospective cohort study of 62 children with video-confirmed epileptic spasms (ES) diagnosed between 2011-2021.
- Analysis included EEG, neuroimaging, genomic testing, and clinical outcomes.
- Median age at ES onset was 23 months; median diagnostic delay was 8 months.
Main Results:
- Aetiology was identified in 95% of cases; structural-malformative causes predominated (63%).
- Misdiagnosis occurred in 76% of children at presentation.
- Epileptic spasms resolved in 86% after epilepsy surgery; 53% were seizure-free at follow-up.
- Cognitive impairment was more common in genetic aetiologies and with ongoing seizures.
Conclusions:
- Prompt recognition of LOES is crucial for better seizure and developmental outcomes.
- Brain malformations and insults are primary causes of LOES.
- Unilateral structural-malformative causes show the best response to epilepsy surgery.
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