Quantitative analysis of background EEG activity in three protocol-dependent groups of patients with epilepsy.

Objective: The aim of this study is to perform quantitative analysis of background EEG activity in patients with epilepsy depending on the presence/absence of the treatment protocol and on the type of therapy administered. Methods: Thirty three patients, selected over a period of 3 years (2006–2009) and diagnosed with epilepsy were divided in 3 equal groups. The first group of patients (7M/4F) were free from antiepileptic medications, the second group (4M/7F) were treated with lamotrigine only, and the third group (3M/8F) received exclusively carbamazepine. The EEG data were obtained under the same conditions and electrodes were applied according to International 10/20 system using standard bipolar montage. For each patient, 40 artefact-free baseline EEG epochs (4 s each during eyes closed) were selected for further analysis. The sampling rate was 256 Hz. Low-cut frequency was 0.53 Hz, whereas high-cut was 30 Hz. Results: Visual analysis of the raw EEG data was performed before obtaining the results. The final quantitative assessment resulted in absolute and relative power spectrum values, calculated within 6 frequency bands: delta (1.50–3.99 Hz), theta (4.00–7.49 Hz), alpha (7.50–11.99 Hz), SMR (12.00–14.99 Hz), beta1 (15–19.99 Hz) and beta2 (20.00–24.99 Hz) in 4 equivalent locations (Fp2-F8, Fp1-F7, P4-O2 and P3-O1). EEG spectral results were statistically evaluated by ANOVA which showed significant difference among the groups for the absolute power (mean values being 5.98, 6.44 and 12.92 μV for each group, respectively) of the delta frequency band in Fp2-F8 location only (F = 3.46 greater then F critical = 3.35, p = 0.05). Conclusion: Quantitative analysis of background EEG activity in epilepsy is a useful tool in discriminating specific groups of patients that are defined by the therapeutic protocol.