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Published on: September 1, 2023
Quantitative EEG biomarkers of cognitive performance in drug-resistant temporal lobe epilepsy
Sofía Lallana1, Samuel López-Maza1, Gemma Ortega2
1Epilepsy Unit, Neurology Department, Research Group on Status Epilepticus and Acute Seizures, Vall d'Hebron Research Institute, Vall d'Hebron University Hospital, Vall d'Hebron Hospital Campus, Barcelona, Spain; Medicine Department, Universitat Autònoma de Barcelona, Barcelona, Spain.
Background:
This study aimed to explore quantitative electroencephalography (qEEG) biomarkers of cognitive performance in drug-resistant temporal lobe epilepsy (TLE) and analyze their relationship with clinical characteristics.
Methods:
Cross-sectional study including adult patients with drug-resistant TLE and a control group. Resting-state, eyes-closed qEEG samples were analyzed using the fast Fourier transform approach. Power spectral density was calculated for four frequency bands: delta (1-3.9 Hz), theta (4-7.9 Hz), alpha (8-12.9 Hz), and beta (13-18 Hz). Neuropsychological tests were administered to TLE patients.
Results:
Twenty-nine TLE patients (mean age 42 ± 8.2 years; 44.8 % women) and 23 age- and sex-matched controls were enrolled. Clinically significant cognitive impairment was found in 86.2 % of patients (58.6 % amnestic). Compared to controls, TLE patients showed increased ipsilateral power spectral density for the theta (p = 0.045), alpha (p = 0.023) and beta bands in the anterior region (p = 0.029) and for the delta band in the posterior region (p = 0.03). Alpha/theta ratio (ATR) was lower in the posterior quadrant of the epileptogenic hemisphere (p = 0.013), and higher seizure frequency correlated with a lower ATR in the ipsilateral temporal region (r: -0.425; p = 0.021). Patients with amnestic cognitive impairment exhibited higher power spectral density across most frequency bands (p < 0.005). Impaired verbal memory and executive function were associated with increased power density.
Conclusion:
Increased power spectral density was evident in all frequency bands in the epileptogenic hemisphere, particularly in those patients with amnestic cognitive impairment. Moreover, higher seizure frequency correlated with a lower ATR in the temporal region. Power spectral analysis can provide useful information in drug-resistant TLE patients.
