Restuccia Domenico, Rubino Marco, Valeriani Massimiliano, Della Marca Giacomo
Department of Neurosciences, Catholic University, Policlinico A. Gemelli, Largo A. Gemelli 8, 00168 Rome, Italy.
Clin Neurophysiol. 2005 Aug;116(8):1774-8. doi: 10.1016/j.clinph.2005.03.024.
Three hertz spike-and-wave (SW) occurrence is caused by the abnormal functioning of the same thalamo-cortical loop generating sleep spindles. In fact, SW preferably occurs during light sleep and transitional phases of the vigilance status. Since high-frequency somatosensory evoked potentials (HF-SEPs) are powerfully modulated by sleep and arousal, we verified whether they can reveal abnormalities of arousal-related structures in two patients having showed sporadic SW discharges during light sleep.
We recorded right median nerve SEPs in two adult patients who suffered since the infancy from childhood absence epilepsy (CAE). Sleep stage-related changes of HF-SEPs were compared to those observed in five healthy volunteers.
HF-SEPs decreased during sleep in controls. By contrast, the amplitude of the subcortical component dramatically increased in CAE patients during phase II NREM sleep. Simultaneous EEG showed normally represented sleep spindles, but not SW discharges.
HF-SEP increase probably reflects the hyperactivation of brain-stem arousal-related structures. During such a hyperactivation no EEG abnormalities were observed.
We hypothesize that HF-SEP increase might reflect a protective mechanism against seizure occurrence during light sleep.
3赫兹棘慢波（SW）的出现是由产生睡眠纺锤波的同一丘脑 - 皮质环路功能异常所致。事实上，SW更易出现在浅睡眠和警觉状态的过渡阶段。由于高频体感诱发电位（HF - SEPs）受睡眠和觉醒的强烈调制，我们验证了在两名浅睡眠期间出现散发性SW放电的患者中，它们是否能揭示与觉醒相关结构的异常。
我们记录了两名自婴儿期起就患有儿童失神癫痫（CAE）的成年患者右侧正中神经的SEP。将HF - SEPs与睡眠阶段相关的变化与在五名健康志愿者中观察到的变化进行比较。
对照组中HF - SEPs在睡眠期间降低。相比之下，在CAE患者的非快速眼动睡眠二期，皮质下成分的振幅显著增加。同步脑电图显示睡眠纺锤波表现正常，但未出现SW放电。
HF - SEP增加可能反映了脑干与觉醒相关结构的过度激活。在这种过度激活期间未观察到脑电图异常。
我们推测HF - SEP增加可能反映了一种在浅睡眠期间防止癫痫发作的保护机制。
