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Tonic and tonic-clonic seizures in the first year of life: Insights from electrographic features
Marta Conti1, Mattia Mercier1, Domenico Serino2
1Neurology, Epilepsy and Movement Disorders Unit, Bambino Gesù, IRCCS Children's Hospital, Full Member of European Reference Network EpiCARE, Rome, Italy.
Insights
Electrographic features of tonic seizures (TS) and tonic-clonic seizures (TCS) in infants can help differentiate between self-limited epilepsies and developmental and epileptic encephalopathies (DEEs). Early identification aids in predicting epilepsy outcomes.
Area of Science:
- Pediatric Neurology
- Epileptology
- Clinical Neurophysiology
Background:
- Tonic seizures (TS) and tonic-clonic seizures (TCS) are common seizure types in infants.
- Distinguishing between self-limited epilepsies and developmental and epileptic encephalopathies (DEEs) is crucial for prognosis and treatment.
- Electrographic seizure patterns may offer insights into underlying epilepsy syndromes in early life.
Purpose of the Study:
- To analyze the electrographic characteristics of TS and TCS in infants.
- To determine if these features correlate with the distinction between self-limited epilepsies and DEEs.
- To evaluate the potential of electrographic patterns for early epilepsy outcome prediction.
Main Methods:
- Retrospective review of video-EEG recordings from 41 infants (1-12 months) with TS or TCS.
- Analysis of seizure duration, focal/generalized ictal EEG onset, and post-ictal generalized EEG suppression (PGES).
- Correlation of electrographic findings with clinical variables including age at onset, genetic, and neuroimaging data.
Main Results:
- Tonic seizures (TS) were exclusively observed in Developmental and Epileptic Encephalopathies (DEEs), unlike tonic-clonic seizures (TCS).
- Focal ictal EEG onset was characteristic of TCS (92%) but absent in TS (0%); generalized onset was seen in all TS.
- Self-limited epilepsies showed more frequent and longer focal ictal EEG onsets and more PGES compared to DEEs.
Conclusions:
- Electrographic patterns of TS and TCS in infants provide valuable clues for differentiating self-limited epilepsies from DEEs.
- The presence or absence of focal ictal EEG onset is a key differentiator.
- These findings can aid in earlier diagnosis and management of infantile epilepsy syndromes.
Objective:
We studied the electrographic features of tonic seizures (TS) with bilateral contraction and tonic-clonic seizures (TCS) without focal signs occurring during the first year of life to evaluate if there is a correlation with outcome.
Methods:
We retrospectively reviewed patients aged 1 to 12 months with at least one TS or TCS recorded with video-EEG between 2011 and 2021 in our Epilepsy Monitoring Unit. We analyzed the following electrographic features: seizure duration, presence and duration of focal ictal EEG onset, and post-ictal generalized EEG suppression (PGES). Among clinical variables, we collected age at epilepsy onset, age at TS and TCS recording, response to anti-seizure medications, genetic and neuroimaging findings, epileptic syndrome classification.
Results:
Overall, we recorded 2577 seizures in 1769 patients. One-hundred-twenty-eight seizures (5%) were clinically labeled either as TS or TCS in 41 patients (2%). Out of 41 patients, 17 (41%) presented with TS, and 24 (59%) with TCS. Thirteen patients (32%) had a Self-limited Epilepsy, and 28 (68%) a Developmental and Epileptic Encephalopathy (DEE). Seventy-two percent of genetically tested patients had pathogenic gene variants. None had structural epilepsy. Mean age at epilepsy onset was 4.48 months (range 3 days-12 months). Age at seizure onset was earlier in patients presenting with TS versus patients presenting with TCS (2.31 months vs. 6.01 months; p = 0.001) and in DEEs versus Self-limited Epilepsies (3.23 months vs. 7.16 months; p = 0.001). TS were exclusively present in DEEs (p = 0.001), and TCS were recorded in both DEEs and Self-limited Epilepsies. Focal ictal EEG onset was evident in 92 % of TCS, and in none of TS. Generalized ictal EEG onset was documented in 100 % of TS, and in 8 % of TCS. Focal ictal EEG onset occurred more frequently (100 % vs. 32 %; p = 0.000) and was significantly longer (30.61 s vs. 16.22 s; p = 0.020) in Self-limited Epilepsies versus DEEs. PGES was observed in 18 out of 41 (44 %) and was more frequent in Self-limited Epilepsies (p = 0.026).
Significance:
This study provides insights into the electroclinical features of TS and TCS in infants that may help distinguish Self-limited Epilepsies from DEEs soon after epilepsy onset.
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