Related Experiment Video
Updated: Oct 22, 2026

Behavioral Characterization of Pentylenetetrazole-induced Seizures: Moving Beyond the Racine Scale
Published on: July 8, 2025
Characteristics of Patients With Epileptic Spasm Onset Over 2 Years of Age
Hirokazu Takeuchi1, Kenjiro Kikuchi1, Haruhito Horita2
1Division of Neurology, Saitama Children's Medical Center, Saitama, Japan; Department of Pediatrics, Jikei University School of Medicine, Tokyo, Japan.
Background:
The definition of late-onset epileptic spasms has shifted from epileptic spasm (ES) onset over one-2 years of age, due to the emergence of infantile epileptic spasms syndrome. This study investigated differences in clinical characteristics between patients who demonstrated ES at one-2 years of age versus >2 years of age.
Methods:
This retrospective study included patients aged ≥one year who developed ES and visited Saitama Children's Medical Center between January 1, 1990, and March 31, 2023. Patients were classified based on age at ES onset into the one-2-year-old group (one-2 years group) and the older-than-2-year-old group (≥2 years group). The clinical characteristics of each group and the differences in clinical characteristics between the two groups were investigated.
Results:
The one-2 years group included 10 patients, while the ≥2 years group comprised 8 patients. Comparison between the two groups revealed that the ≥2-year group exhibited higher developmental quotient at ES onset, longer lead time, and more misdiagnosis, and less hypsarrhythmia on interictal electroencephalography. At the last follow-up, intellectual disability (ID) was present in all patients across both cohorts. Regarding the severity distribution of ID, higher proportion of patients in the ≥2 years group demonstrated mild ID and a lower proportion demonstrated severe ID compared to those in the one-2 years group.
Conclusions:
Age at ES onset may reflect different clinical phenotypes and outcomes within the late-onset spectrum.
Related Concept Videos
Epilepsy ll: Types
Seizures: Classification
Seizures are typically classified into two main categories: focal and generalized seizures.
Focal Seizures
Focal seizures originate from specific regions of the brain. These seizures are further sub-classified into two types:
Seizures l: Introduction
Epilepsy and Seizures: Overview
Various factors can trigger epilepsy, including genetic factors, brain damage, metabolic causes, and unknown etiology. Diagnosis of epilepsy involves electroencephalography (EEG), which...
Seizures ll: Types
Alterations in Muscle Tone ll
