Quantitative EEG biomarkers of cognitive performance in drug-resistant temporal lobe epilepsy.

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.