Researchers can now detect epilepsy without waiting for seizures

Good news!

"... The group made giant strides toward a different way of detecting seizures. New research found that changes in large-scale neuronal activations can be detected in the brains of epileptic patients during periods when no seizure is taking place. The study ... compared the high-density EEGs of 37 patients with temporal lobe epilepsy to those of 37 healthy controls. ...
“We found that the alteration of the spreading of neuronal avalanches in temporal lobe epilepsy is clustered around those brain areas which are fundamental for seizure initiation and diffusion” ... “This opens up the possibility to a new preliminary diagnostic method, especially important for the difficult cases where scalp EEG fails to detect seizures and additional investigations are necessary.” ..."

From the abstract and key points:

"Abstract

Objective

Large aperiodic bursts of activations named neuronal avalanches have been used to characterize whole-brain activity, as their presence typically relates to optimal dynamics. Epilepsy is characterized by alterations in large-scale brain network dynamics. Here we exploited neuronal avalanches to characterize differences in electroencephalography (EEG) basal activity, free from seizures and/or interictal spikes, between patients with temporal lobe epilepsy (TLE) and matched controls.

Method

We defined neuronal avalanches as starting when the z-scored source-reconstructed EEG signals crossed a specific threshold in any region and ending when all regions returned to baseline. This technique avoids data manipulation or assumptions of signal stationarity, focusing on the aperiodic, scale-free components of the signals. We computed individual avalanche transition matrices to track the probability of avalanche spreading across any two regions, compared them between patients and controls, and related them to memory performance in patients.

Results

We observed a robust topography of significant edges clustering in regions functionally and structurally relevant for the TLE, such as the entorhinal cortex, the inferior parietal and fusiform area, the inferior temporal gyrus, and the anterior cingulate cortex. We detected a significant correlation between the centrality of the entorhinal cortex in the transition matrix and the long-term memory performance (delay recall Rey–Osterrieth Complex Figure Test).

Significance

Our results show that the propagation patterns of large-scale neuronal avalanches are altered in TLE during the resting state, suggesting a potential diagnostic application in epilepsy. Furthermore, the relationship between specific patterns of propagation and memory performance support the neurophysiological relevance of neuronal avalanches.

Key Points

1. Investigation of the brain dynamics during resting-state activity in patients with temporal lobe epilepsy (TLE) using neuronal avalanches (i.e., large-scale patterns of activation)
2. We found higher transition probabilities in patients with TLE in the entorhinal cortex, inferior temporal and fusiform gyri, and anterior cingulate cortex
3. We found higher eigenvector centrality of the left entorhinal cortex in the avalanche transition matrix, which was related to reduced long-term memory performance
4. Discussion of the potential application of the avalanche transition matrix as a diagnostic tool in presurgical evaluations and epilepsy type differentiation"

Researchers can now detect epilepsy without waiting for seizures

Altered spreading of neuronal avalanches in temporal lobe epilepsy relates to cognitive performance: A resting-state hdEEG study (open access)

FIGURE 1 Graphical representation of analysis pipeline.