The significance of interictal electroencephalogram analysis based on the grand total electroencephalogram score in early assessment of cognitive impairment in epilepsy patients

Purpose: Epilepsy is a widespread neurological disorder that increases the risk of cognitive impairment (CI) or dementia. We aimed to assess the relationship between cognition and interictal electroencephalogram (EEG) in epilepsy patients, using the Grand Total EEG (GTE) score. Additionally, we investigated the GTE score's utility in the early detection of CI in these patients.

Methods: Data from 93 patients diagnosed with unexplained epilepsy at the Affiliated Hospital of Yangzhou University were analyzed. EEG recordings and cognitive evaluations were performed. Patients were categorized into three groups based on their Montreal Cognitive Assessment (MoCA) scores: normal cognitive (NC) group, mild cognitive impairment (MCI) group, and dementia group. The study included analysis of correlations between cognitive test results and clinical characteristics. Additionally, the influence of GTE scores and subscores on cognition was examined. Statistical analyses included one-way analysis of variance (ANOVA), Kruskal-Wallis H-test, Mann-Whitney U-test, Chi-square test, Spearman rank correlation analysis, and multiple linear regression.

Results: (1) There was a significant negative correlation between cognitive test scores and GTE scores. Strong negative correlations were found between cognition (MoCA) and the GTE score (ρ = -0.754, P < 0.001), as well as for the subscores "Diffuse Slow Activity" (ρ = -0.712, P < 0.001), "Frequency of Rhythmic Background Activity" (ρ = -0.490, P < 0.001), and "Paroxysmal Activity" (ρ = -0.565, P < 0.001). (2) Multiple linear regression analysis identified the GTE score, "Diffuse Slow Activity", "Paroxysmal Activity", age, and education as significant predictors of cognitive decline. (3) At a threshold of 4.5, the GTE score effectively differentiated between individuals with and without CI, demonstrating a sensitivity of 73.8 % and a specificity of 93.7 %.

Conclusion: The GTE score provides clinically valuable information for the early detection of CI in patients with epilepsy. As CI worsens in epilepsy patients, the GTE score, Diffuse Slow Activity, Frequency of Rhythmic Background Activity, and Paroxysmal Activity increase. Healthcare providers should focus on managing not only seizures but also interictal EEG abnormalities to prevent or mitigate the risk of CI.