High-frequency oscillations in a spectrum of pediatric epilepsies characterized by sleep-activated spikes in scalp
Yuji Ohuchi1, Tomoyuki Akiyama2, Masao Matsuhashi3
1Department of Child Neurology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 5-1 Shikata-cho 2-chome, Kita-ku, Okayama 700-8558, Japan; Department of Pediatrics, Tohoku University School of Medicine, 1-1 Seiryo-cho, Aoba-ku, Sendai 980-0872, Japan.
Insights
Continuous spike-and-wave during sleep (CSWS) epilepsy in children is characterized by a high ratio of high-frequency oscillations, known as ripples, per spike. This finding, observed in the largest patient cohort to date, may be linked to the underlying pathophysiology of this condition.
Area of Science:
- Neuroscience
- Pediatric Neurology
- Epileptology
Background:
- High-frequency oscillations (HFOs), specifically ripple-band activity (80-200 Hz), are increasingly recognized in pediatric epilepsies.
- Sleep-activated spikes are a hallmark of certain pediatric epilepsy syndromes, including epileptic encephalopathy with continuous spike-and-wave during sleep (CSWS).
- The precise role and characteristics of ripple activity in relation to spike generation in various pediatric epilepsy types remain an area of active investigation.
Purpose of the Study:
- To investigate and characterize ripple-band oscillations in the scalp electroencephalogram (EEG) of children with various epilepsy types exhibiting sleep-activated spikes.
- To compare the ratio of ripples per spike across different pediatric epilepsy syndromes, with a focus on CSWS.
Main Methods:
- A cohort of 94 children with diverse epileptic disorders was studied, including idiopathic and non-idiopathic CSWS, benign epilepsy with centrotemporal spikes (BECTS), Panayiotopoulos syndrome, other focal epilepsies (oFE), and focal spikes without clinical seizures (Latent).
- Ripple oscillations were detected using a semi-automatic tool that identifies localized power increases in the EEG.
- The ratio of ripples per spike was calculated and compared between the different epilepsy groups.
Main Results:
- The idiopathic CSWS group exhibited a significantly higher median ratio of ripples per spike (5.73) compared to BECTS (0.39), Panayiotopoulos syndrome (0.02), oFE (0.35), and Latent groups (0).
- These findings were statistically significant (p < 0.01) and indicated a particularly high prevalence of ripples in CSWS.
- Ripple frequency was observed to be higher in younger children.
Conclusions:
- This study provides the first confirmation of a high ripple-to-spike ratio in CSWS, based on the largest patient cohort studied to date.
- The dense generation of ripples in CSWS, associated with numerous spikes during sleep, characterizes the condition.
- This high ripple activity is suggested to be closely linked to the pathophysiology of CSWS, a severe form of pediatric epileptic encephalopathy.
Objective:
We studied ripple-band (80-200 Hz) high-frequency oscillations in scalp electroencephalogram (EEG) in various pediatric epilepsies featuring sleep-activated spikes, such as epileptic encephalopathy with continuous spike-and-wave during sleep (CSWS) and investigated their characteristics.
Methods:
The subjects were 94 children with epileptic disorders including idiopathic and non-idiopathic CSWS, benign epilepsy with centrotemporal spikes (BECTS), Panayiotopoulos syndrome, other types of focal epilepsies (oFE), and focal spikes without clinical seizures (Latent). We detected ripple oscillations using a semi-automatic detection tool based on localized power increase.
Results:
In the idiopathic CSWS Group, the median ratio of ripples per spike in the initial EEG was 5.73, which was significantly higher than those in the BECTS, Panayiotopoulos syndrome, oFE, and Latent Groups (0.39, 0.02, 0.35, 0, respectively, all with p < 0.01). Ripples were particularly frequent at younger ages.
Conclusions:
This paper is the first to confirm a high ratio of ripples per spike in CSWS in the largest number of patients to date.
Significance:
The dense generation of ripples, which occurs through a combination of heavy loading of individual spikes with ripples and large numbers of spikes during sleep, characterizes CSWS and might be closely related to the pathophysiology of this epileptic encephalopathy.
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