Effects of sleep epileptiform discharge on aural pre-attentive processing of children with benign childhood epilepsy with central-temporal spikes

Abstract

Objective To explore the relationship between aural pre-attentive processing and non-rapid eye movement(NREM) sleep interictal epileptiform discharge (IED) in children with benign childhood epilepsy with central-temporal spikes (BECTS), in order to provide objective electrophysiological basis for early assessment of cognitive function lesion of BECTS children and intervention. Methods Twenty-nine children diagnosed as BECTS in the Second Affiliated Hospital of Xinxiang Medical University from February 2012 to November 2015 were selected, including 17 males and 12 females, and they were 4-14 years old with average age of (9.17±2.42) years, and the course of disease was 0.5-4.0 years.Twenty healthy children who had hospital routine check-up were selected as healthy control group, containing 14 males and 6 females, and they were 5-13 years old with average age of (8.55±3.09) years.Mismatch negativity (MMN) test was carried out in both groups, and the MMN amplitudes and latencies were analyzed.The long-term video electroencephalogram (VEEG) monitoring was conducted in the BECTS group to analyze the discharge phases (waking, sleep), locations and the IED indexes.The intergroup MMN indexes and the correlation between MMN and VEEG in the BECTS group were compared. Results The VEEG showed that the sleep structure of BECTS children did not change obviously.All children′s epileptiform discharges were located in the Rolandic area, including 11 cases on the left side, 8 cases on the right side, and 10 cases on both sides.Epilepsy discharge time: 17 patients showed epileptiform discharges in sleep stages only and 12 patients showed epileptiform discharge in both sleep and waking stages.Epileptiform discharges of the 12 patients increased more significantly in sleep stage than that in waking stage [(40.24±25.15) times/min vs.(1.92±1.38) times/min], and the difference was statistically significant(t=5.270, P=0.000). The sample IED index in stage 1 and 2 of NREM was (40.73±10.69) times/min, in which 2 cases had IED indexes 80 times/min who reached electrical status epilepticus during sleep, and others were 17.2-64.6 times /min.Clinical seizures in sleep stages were monitored in only 4 cases, which showed an electro-clinical segregation phenomenon from large quantities of sleep IED.The MMN amplitude was lower in the BECTS group than that in the healthy control group [(6.06±1.89) μV vs.(7.28±1.64) μV], and the difference was statistically significant(t=2.346, P=0.025). Latency of BECTS group was longer than that in the healthy control group [(191.37±40.13) ms vs.(179.35±39.80) ms], but the difference was not statistically significant(t=1.037, P=0.355). Correlation analysis showed that the MMN amplitude was negatively related to discharge phases (r=-0.407, P<0.05) and the IED indexes (r=-0.644, P<0.01), and latency was positively related to the IED indexes (r=0.386, P<0.05), while the other VEEG indexes were not correlated with MMN. Conclusions The BECTS children have aural pre-attentive processing disturbance, especially unconscious automatic processing ability impairment, which weaken attention switch action of automatic processing switching to focused attention processing and fail to filter irrelevant information effectively.Sleep IED is an important factor in impairing the formation and reinforcement of acoustic discrimination and memory trace, interfering the acquisition, proce-ssing, storage and matching of new information, which induces children pre-attentive processing disturbance.The MMN may discover the electrophysiological changes of children pre-attentive processing disturbance in early stage. Key words: Benign childhood epilepsy; Audition; Pre-attentive processing; Interictal epileptiform discharge; Mismatch negativity