Quantitative analysis of visually normal EEG reveals spectral power abnormalities in temporal lobe epilepsy

Maria Celeste Bonacci; Ilaria Sammarra; Maria Eugenia Caligiuri; Miriam Sturniolo; Iolanda Martino; Patrizia Vizza; Pierangelo Veltri; Antonio Gambardella

doi:10.1016/j.neucli.2024.102951

Quantitative analysis of visually normal EEG reveals spectral power abnormalities in temporal lobe epilepsy

Neurophysiol Clin. 2024 Mar 28;54(3):102951. doi: 10.1016/j.neucli.2024.102951. Online ahead of print.

Authors

Maria Celeste Bonacci¹, Ilaria Sammarra², Maria Eugenia Caligiuri³, Miriam Sturniolo², Iolanda Martino⁴, Patrizia Vizza¹, Pierangelo Veltri⁵, Antonio Gambardella²

Affiliations

¹ Department of Medical and Surgical Science, University of Magna Graecia, Italy.
² Institute of Neurology, Department of Medical and Surgical Sciences, University of Magna Graecia, Italy.
³ Neuroscience Research Center, Department of Medical and Surgical Sciences, University Magna Graecia, Italy. Electronic address: me.caligiuri@unicz.it.
⁴ U.O.C. Neurology, Renato Dulbecco University hospital, Italy.
⁵ DIMES, Università della Calabria, Italy.

PMID: 38552384
DOI: 10.1016/j.neucli.2024.102951

Abstract

Objective: To compare quantitative spectral parameters of visually-normal EEG between Mesial Temporal Lobe Epilepsy (MTLE) patients and healthy controls (HC).

Method: We enrolled 26 MTLE patients and 26 HC. From each recording we calculated total power of all frequency bands and determined alpha-theta (ATR) and alpha-delta (ADR) power ratios in different brain regions. Group-wise differences between spectral parameters were investigated (p < 0.05). To test for associations between spectral-power and cognitive status, we evaluated correlations between neuropsychological tests and quantitative EEG (qEEG) metrics.

Results: In all comparisons, ATR and ADR were significantly decreased in MTLE patients compared to HC, particularly over the hemisphere ipsilateral to epileptic activity. A positive correlation was seen in MTLE patients between ATR in ipsilateral temporal lobe, and results of neuropsychological tests of auditory verbal learning (RAVLT and RAVLT-D), short term verbal memory (Digit span backwards), and executive function (Weigl's sorting test). ADR values in the contralateral posterior region correlated positively with RAVLT-D and Digit span backwards tests.

Discussion: Results confirmed that the power spectrum of qEEG is shifted towards lower frequencies in MTLE patients compared to HC.

Conclusion: Of note, our results were found in visually-normal recordings, providing further evidence of the value of qEEG for longitudinal monitoring of MTLE patients over time. Exploratory analysis of associations between qEEG and neuropsychological data suggest this could be useful for investigating effects of antiseizure medications on cognitive integrity in patients.

Keywords: Alpha Delta Ratio (ADR); Alpha Theta Ratio (ATR); Mesial Temporal Lobe Epilepsy (MTLE); Quantitative EEG; Spectral power abnormalities; Visually normal EEG.