Characteristics of ictal thalamic EEG in pediatric-onset neocortical focal epilepsy
Benjamin Edmonds1, Makoto Miyakoshi2, Luigi Gianmaria Remore3
1Division of Pediatric Neurology, Department of Pediatrics, UCLA Mattel Children's Hospital, David Geffen School of Medicine, Los Angeles, CA, USA.
Insights
Ictal electroencephalography (EEG) changes were consistently detected in the centromedian (CM) and anterior nucleus (AN) of the thalamus during neocortical seizures, suggesting potential for closed-loop neuromodulation.
Area of Science:
- Neuroscience
- Epileptology
- Clinical Neurophysiology
Background:
- Neocortical drug-resistant epilepsy often requires advanced diagnostic techniques.
- The role of thalamic nuclei in seizure generation and propagation is an area of ongoing research.
- Stereoelectroencephalography (SEEG) provides high-resolution intracranial EEG data.
Purpose of the Study:
- To characterize ictal electroencephalography (EEG) changes within the centromedian (CM) and anterior nucleus (AN) of the thalamus.
- To evaluate the feasibility of detecting seizure activity in these thalamic nuclei using SEEG.
Main Methods:
- Analysis of 40 habitual seizures in nine pediatric-onset epilepsy patients with SEEG and thalamic coverage.
- Both visual and quantitative EEG analysis of cortical and thalamic signals.
- Measurement of amplitude and cortico-thalamic latencies of broadband frequencies at ictal onset.
Main Results:
- Consistent detection of ictal EEG changes in CM and AN nuclei within 400 ms of seizure onset in 95% of cases.
- Low-voltage fast activity was the most common ictal pattern observed.
- Quantitative analysis confirmed power changes across frequency bands, with variable latencies; no significant difference between CM and AN detection.
Conclusions:
- Ictal EEG changes are consistently observed in the centromedian and anterior nucleus of the thalamus during neocortical seizures.
- These findings suggest the potential for thalamic closed-loop systems to detect and modulate seizure activity in neocortical epilepsy.
Objective:
To characterize ictal EEG change in the centromedian (CM) and anterior nucleus (AN) of the thalamus, using stereoelectroencephalography (SEEG) recordings.
Methods:
Forty habitual seizures were analyzed in nine patients with pediatric-onset neocortical drug-resistant epilepsy who underwent SEEG (age 2-25 y) with thalamic coverage. Both visual and quantitative analysis was used to evaluate ictal EEG signal in the cortex and thalamus. The amplitude and cortico-thalamic latencies of broadband frequencies at ictal onset were measured.
Results:
Visual analysis demonstrated consistent detection of ictal EEG changes in both the CM nucleus and AN nucleus with latency to thalamic ictal EEG changes of less than 400 ms in 95% of seizures, with low-voltage fast activity being the most common ictal pattern. Quantitative broadband amplitude analysis showed consistent power changes across the frequency bands, corresponding to ictal EEG onset, while while ictal EEG latency was variable from -18.0 seconds to 13.2 seconds. There was no significant difference between detection of CM and AN ictal activity on visual or amplitude analysis. Four patients with subsequent thalamic responsive neurostimulation (RNS) demonstrated ictal EEG changes consistent with SEEG findings.
Conclusions:
Ictal EEG changes were consistently seen at the CM and AN of the thalamus during neocortical seizures.
Significance:
It may be feasible to use a closed-loop system in the thalamus to detect and modulate seizure activity for neocortical epilepsy.
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