Sobaniec W, Kulak W, Bielewicz B, Sobaniec P
Department of Pediatric Neurology and Rehabilitation, Medical University of Bialystok, Poland.
Adv Med Sci. 2008;53(2):321-5. doi: 10.2478/v10039-008-0052-6.
Annual changes in powers of the close-eyed EEG were measured over 12 months in 12 patients with epilepsy.
The present study included 12 patients aged 14.6+/-2.7 years with chronic epilepsy, suffering for 6-14 years. EEGs were recorded every month between 9 and 11 a.m. Five patients had generalized seizures and 7 partial complex seizures secondarily generalized. Visual analysis of EEG was performed before the quantitative assessment. The signals were recorded using a set of 14 (F3, F4, F7, F8, C3, C4, P3, P4, 01, 02, T3, T4, T5, T6) scalp electrodes. For each patient, 20 artifact-free EEG epochs, each of 2 s. duration were selected for spectral analysis to calculate spectral power. The sampling frequency was 240 Hz. Frequencies below 1 Hz and above 70 Hz were eliminated by digital filtering. The channels were recorded relative to a vertex reference. A fast Fourier transformation algorithm of signal processing was used to obtain the power spectrum of each lead. Absolute power spectrum was calculated within 4 frequency bands: delta (1-3.99 Hz), theta (4-7.99 Hz), alpha (8-12.99 Hz), and beta (13-30.99 Hz).
We found the abnormalities to be predominantly focal in EEG. None of the EEG recordings were normal, and the power spectra differed over the year. A statistically significant increase of delta and theta bands in May and a decrease of alpha bands in September was found. We did not find positive correlations between the changes in the quantitative EEG analysis and the number of seizures in patients.
These findings suggest the annual variations of EEG in patients with chronic epilepsy. Furthermore studies are needed to clarify the annual variations of EEG among healthy volunteers.
对12例癫痫患者进行为期12个月的闭眼脑电图功率年度变化测量。
本研究纳入12例年龄为14.6±2.7岁的慢性癫痫患者，病程6 - 14年。每月上午9点至11点记录脑电图。5例患者为全身性发作，7例为部分性复杂性发作继发全身性发作。在进行定量评估之前先对脑电图进行视觉分析。使用一组14个（F3、F4、F7、F8、C3、C4、P3、P4、O1、O2、T3、T4、T5、T6）头皮电极记录信号。为每位患者选择20个无伪迹的脑电图片段，每个片段持续2秒用于频谱分析以计算频谱功率。采样频率为240Hz。通过数字滤波去除低于1Hz和高于70Hz的频率。记录的通道相对于头顶参考点。使用信号处理的快速傅里叶变换算法获得每个导联的功率谱。在4个频段内计算绝对功率谱：δ（1 - 3.99Hz）、θ（4 - 7.99Hz）、α（8 - 12.99Hz）和β（13 - 30.99Hz）。
我们发现脑电图异常主要为局灶性。所有脑电图记录均不正常，且一年中的功率谱有所不同。发现5月δ和θ频段有统计学显著增加，9月α频段有下降。我们未发现患者脑电图定量分析变化与癫痫发作次数之间存在正相关。
这些发现提示慢性癫痫患者脑电图存在年度变化。还需要进一步研究以阐明健康志愿者脑电图的年度变化。
