The relative influence of epileptic EEG discharges, short nonconvulsive seizures, and type of epilepsy on cognitive function

PURPOSE: This study addressed whether cognitive impairment in children with epilepsy is caused by disease-related stable factors, such as the type of epilepsy, or by acute effects of paroxysmal epileptic activity such as epileptic EEG discharges. We studied a nonselected group with short nonconvulsive seizures, as these seizures may elude detection and may therefore persist over a longer period. In this group, the diagnostic issue is to differentiate between the combined effects of several epilepsy-related factors on cognition. METHODS: All children were assessed with 32-channel EEG, synchronized with a computerized cognitive test system and a video-monitoring system. Recording time was 2 h. The primary inclusion criteria were unclear seizures and fluctuations in cognitive performance and/or frequent epileptic EEG discharges in a recent EEG. RESULTS: One hundred fifty-two patients met the inclusion criteria; 31 patients appeared not to have a diagnosis of epilepsy and were used as a nonepilepsy control group. Our results show that type of epilepsy has an impact on stable cognitive functions, such as educational achievement. Paroxysmal epileptic activity (acute effects of seizures and epileptic EEG discharges) affects primarily transient mechanistic cognitive processes (alertness, mental speed). CONCLUSIONS: These results suggest that the effects of paroxysmal epileptic activity on transient cognitive mechanisms may accumulate over time and consequently affect the more stable aspects of cognitive function such as educational achievement. The clinical relevance is that early detection of the cognitive impact of seizure-related activity and subsequent treatment may prevent its detrimental impact on cognitive and educational development.     

Reading abilities and cognitive functions of children with epilepsy: influence of epileptic syndrome

Children with epilepsy are at risk of developing learning disorders. To explore the influence of the epileptic syndrome on reading abilities, we have compared the neuropsychological profile of 12 children with benign idiopathic epilepsy with rolandic spikes, 10 with temporal lobe epilepsy and 12 with idiopathic generalized epilepsy. Children underwent a selection of standardised tests designed to assess: oral language, reading, short-term memory, attention and behavioural adjustment. Analysis of variance was adjusted according to age of onset of the epileptic syndrome, duration of the syndrome, and performance IQ for each group. Children with temporal lobe epilepsy (TLE) had significantly lower scores for reading speed and comprehension, but epileptic variables (the age of onset of epilepsy, duration and activity of epilepsy) had influenced academic performances. In the TLE group there was a clear effect of the topography of the epileptic foci (left-side TLE vs. right-side TLE) on reading profile. Furthermore, the effect of epileptic syndromes was found in phonological, semantic and verbal working memory deficits in the TLE group. To a lesser extent children with idiopathic generalized epilepsy (IGE) also exhibit cognitive deficit. The results of the present study lend support to epilepsy-specific patterns of neuropsychological dysfunction in children that should be considered to improve remediation of academic underachievement in these populations.     

Effect of epilepsy, seizures and epileptiform EEG discharges on cognitive function

Patients with an established diagnosis of epilepsy were included in three groups on the basis of the absence (Group 2) or presence (Group 3) of epileptiform EEG discharges or subtle seizures (Group 4) during the cognitive assessment procedure. A separate age-matched non-epileptic control group (Group 1) was formed. Twenty-five patients were included in each of the four groups. Thus, a total of 100 patients were investigated. The patients were assessed with continuous 21-channel EEG and video-monitoring, combined with cognitive testing. The results show consistently lower performance on cognitive tests for Group 4, the group with subtle seizures. The difference with the control group was significant for the intelligence subtests and for the complex information processing test (p<0.05). No transient cognitive impairment was found. The results are discussed in the light of possible factors that may be responsible for the lower test-scores in the patients of Group 4: both the ictal effects of the seizures themselves, postictal effects and the effects of the epileptiform EEG discharges may have had an impact on cognitive performance. Finally the absence of evidence for transient cognitive impairment in a group with frequent epileptiform EEG discharges is discussed in detail.     

Pathogenesis of epileptic seizures and epilepsy after stroke

Stroke is an important cause of seizures and epilepsy in adults, particularly among the elderly. The incidence of stroke increases yearly as life expectancy increases and the number of patients with post-stroke seizures and epilepsy is also rising. Post-stroke epilepsy accounts for nearly 50% of newly diagnosed epilepsy among patients over 60 years of age. With increasing stroke awareness and advanced treatments, increased attention is paid to post-stroke seizures and epilepsy including its diagnosis and treatment. There has been a plethora of research on the pathogenesis of seizures and epilepsy after stroke. And thus, the research advances in the pathogenesis and related therapeutic targets of post-stroke seizures and epilepsy will be reviewed in this article.     

唑尼沙胺对戊四氮致痫小鼠认知功能的影响

目的探讨唑尼沙胺(ZNS)对癫痫小鼠的认知功能影响及抗癫痫作用。方法利用戊四氮(PTZ)致痫小鼠模型,通过Morris水迷宫实验、神经元特异性烯醇化酶(NSE)及海马组织形态学的改变,观察ZNS对癫痫小鼠的认知功能影响及抗癫痫作用。结果正常组小鼠无惊厥发作,血清NSE水平在正常范围,海马组织结构正常;癫痫组惊厥出现时间早,发作程度重,血清NSE水平明显高于其它两组,海马组织结构紊乱、疏松;ZNS组惊厥出现时间晚,发作程度轻,血清NSE水平略高于正常组而显著低于癫痫组,海马组织结构无显著变化。结论 ZNS有明确抗癫痫作用,通过控制癫痫发作,有效的改善致痫小鼠的认知功能。     

Incidence of epilepsy and predictive factors of epileptic and non-epileptic seizures.

PURPOSE: To estimate the incidence of unprovoked seizures (US) and epilepsy in a general population from the southern part of the Netherlands, in relation to age, sex, etiology and seizure type, and to identify predictive factors of the epileptic and non-epileptic seizures. METHODS: All patients aged > or =14 years with a first seizure or who had undiagnosed seizures before the study period were included. Patients were identified from different sources and were independently evaluated and classified by a team of neurologists. A predictive profile for the occurrence of epileptic and non-epileptic seizures was obtained by stepwise logistic regression analysis. RESULTS: The overall annual incidence was 55/100,000 and 30/100,000 for US and epilepsy, respectively. The age-specific annual incidence of US and epilepsy increased with age and reached 120/100,000 and 62/100,000 for the > or =65 years of age group, respectively. The incidence of epilepsy and US in males was higher than in females and partial seizures prevailed over generalized seizures (40 versus 9/100,000). In up to 35% of the cases with US or epilepsy, the etiology was mainly cerebrovascular disease and brain tumors. Predictors for epileptic versus non-epileptic seizures of organic origin were an epileptiform EEG pattern (OR=0.06) versus a history of hypertension (OR=2.8) or cardiovascular disease (OR=5.4). Strong predictors for seizures of non-organic origin were female sex (OR=2.2) and head injury (OR=2.4). CONCLUSIONS: The incidence of US and epilepsy (overall, and age-, sex-, seizure-specific) was similar to those reported by other developed countries. The predictive factors found in this study may assist in the early diagnosis of seizures.     

Acute psychosis and epileptic seizures as the presenting symptom of late-onset epilepsy

We report two patients with no history of psychosis or epilepsy presenting with acute psychosis and epileptic seizures as the initial symptom of late-onset epilepsy. Seizures and psychosis resolved with phenytoin. Case 1 presented a recurrence of both psychosis and seizures following abrupt withdrawal of antiepileptic drugs.     

Predictors for recurrence of epileptic seizures in a general epilepsy population

The aim of our study was to identify predictors for recurrence of epileptic seizures in a large county hospital population. We identified 956 patients (18-67 years) with ICD 9 code 345 as primary diagnosis, seen at the Central Hospital of Akershus over 7 years (1987-1994). The diagnosis of epilepsy was confirmed for 696 of the patients. These were divided into two groups: (1) no seizures during the previous year (n = 485) and (2) seizures during the previous year (n = 184). To identify predictors for recurrence of seizures, we used neurologic deficit, number of AEDs used, CT-scan findings, EEG findings, aetiology, gender, age below and above 50 years and comorbidity as independent variables in a logistic regression model. In a univariate analysis, the strongest predictors for recurrence of seizures were: age above 50 years (OR = 5.2;P < 0.0001), known aetiology (OR = 1.4;P = 0.04) and use of two or more AEDs (OR = 5. 7;P < 0.0001). In the multivariate analysis age, more than 50 years (OR = 1.7;P = 0.0216) and use of two or more AEDs (OR = 5.6;P < 0.0001) were the only predictors for recurrence of epileptic seizures.     

Acute cognitive effects of nonconvulsive difficult-to-detect epileptic seizures and epileptiform electroencephalographic discharges

This study compares the acute cognitive effects of short nonconvulsive seizures with the effects of interictal epileptiform electroencephalographic (EEG) discharges in children. The study is a prospective, standardized, nonrandomized, and open clinical comparative study. Eligible patients were included when they had (a) unclear seizures and fluctuations in cognitive performance and (b) frequent epileptiform EEG discharges in a recent EEG. All children were assessed with EEG/video (Brainlab) simultaneously with computerized neuropsychologic testing (FePsy) assessing motor speed/alertness, mental speed/attention, and memory function. Eleven patients with short nonconvulsive seizures during cognitive testing were included and compared with 11 matched patients with interictal epileptiform EEG discharges during cognitive testing but without seizures. Patients included in both groups had a reconfirmed diagnosis of epilepsy. Cognitive performance for both groups was compared. Statistical analysis showed significant correlations between the number of seizures (during cognitive testing) and impaired alertness and between the duration of the ictal period and memory impairment. Interictal epileptiform EEG discharges do not have an additional independent effect on cognitive function. The results demonstrate the accumulating cognitive effect of seizures and illustrate that frequent seizures, even when these are short in duration and with subtle symptomatology, can have a substantial impact on daily life and can lead to state-dependent learning impairment. Alertness and short-term memory appeared to be the functions that are most vulnerable for the acute effects of seizures.     

Myoclonic astatic epilepsy: an age-dependent epileptic syndrome with favorable seizure outcome but variable cognitive evolution

The objective of the study was to explore clinical, electroencephalography (EEG), neuropsychological features and prognosis of myoclonic-astatic epilepsy (MAE). Of 327 children aged between 1 and 9 years with a diagnosis of generalized epilepsy followed between 2000 and 2008, 18 (5.5%) had MAE. Male significantly predominated (88.9%). Age at onset ranged from 2.3 to 4.9 years (mean 3.6 years). Median follow-up period was 6.3 years. In addition to myoclonic-astatic seizures patients had myoclonic seizures (66.7%), drop attacks (72.2%), head drops (77.8%) absences (88.9%), tonic-clonic generalized seizure (77.8%), tonic seizures (38.9%), non-convulsive status epilepticus (16.7%). Seven patients (38.9%) had an epileptic encephalopathy. At onset, interictal epileptiform and slow abnormalities were recorded, respectively, in 100% and 77.8% of patients. EEG abnormalities disappeared in all patients within 4 years since the onset. At long-term follow-up, two patients developed focal abnormalities typical of rolandic epilepsy and two patients photosensitivity. On neuropsychological testing 66.7% of patients had a normal IQ (mean 81.2±17.0, range 47-105, median 84.5) after a mean period of 4.4 years since the last seizure. Sixteen out of 18 patients remitted within 3.5 years since the onset and in two patients tonic seizures persisted. MAE is generalized childhood epilepsy: although cognitive functions might deteriorate, outcome is good regarding seizures.     

Cluster of epileptic spasms preceded by focal seizures observed in localization-related epilepsy

This study observed six cases of localization-related epilepsy (LRE) with a cluster of epileptic spasms (ES) preceded by focal seizures (FS), defined as FS-ES. Initially, the FS was observed at a mean age 13 months; subsequently FS-ES occurred at the mean age 6 years and 3 months. The average duration from FS to FS-ES was 5 years and 1 month. All cases showed plural types of seizure (more than 2), severe mental retardation, multifoci in an interictal electroencephalogram (EEG), and abnormal findings of brain magnetic resonance imaging or computed tomography. Moreover, it was noted that high-voltage spikes were observed in the occipital area in rapid eye movements sleep on overnight EEG. According to a long-term follow-up study (average 13 years and 4 months), the 6 cases with FS-ES were divided into two types of prognosis. In 2 cases of neural cell migration disorder, the FS-ES could be detected, but in 4 cases of cerebral disorder after birth, it had disappeared. To predict a risk factor for LRE with FS-ES, six cases of FS-ES were compared with 27 cases of LRE without FS-ES. As a result of this study, there is a possibility that infants with severe brain damage may thus demonstrate frequent partial seizures and subsequently develop FS-ES.     

Effects of vigabatrin on partial seizures and cognitive function.

Forty five patients with refractory partial seizures were studied in a prospective, randomised, placebo controlled, add on, parallel group, double blind trial of the new antiepileptic drug vigabatrin (1.5 g twice daily) followed by open treatment. Seizure frequency was monitored throughout an eight week baseline, 20 weeks double blind, and up to 18 months of open vigabatrin treatment. Cognitive function, including measures of memory and concentration, mood, and behaviour were assessed at baseline and again during the 20th week of treatment. Vigabatrin was associated with a significant reduction in a measure of motor speed and overall score on a design learning test in the first 20 weeks of treatment. In comparison with the baseline period, vigabatrin treatment was associated with a significant reduction in median complex partial seizure frequency four to 12 and 12 to 20 weeks after commencing vigabatrin (-66% and -69% in the vigabatrin group, +50% and +25% in the placebo group). Ten of 20 patients on vigabatrin and four of 23 on placebo showed a > 50% reduction in complex partial seizure frequency in the last eight weeks of double blind treatment. At least 60% of responders had maintained the response to vigabatrin when assessed during the open phase of the trial at 44 weeks. Two patients discontinued vigabatrin because of depression, which resolved on drug withdrawal.     

Hydrocephalus and epileptic seizures

Is there an association between shunted hydrocephalus and the development of epileptic seizures? To answer this question a retrospective review of the medical records of 197 patients with shunted hydrocephalus was undertaken. In this series 17% of patients with hydrocephalus developed seizures. No correlation was found between the occurrence of epileptic seizures and a shunt malfunction, the number of shunts placed, the age of the patient at the initial shunt procedure or the location of the shunt. Patients with hydrocephalus who had significant cognitive delay or significant motor disability were significantly more likely to develop seizures than patients who did not. The findings of this review support the hypothesis that the occurrence of seizures in children with hydrocephalus is related to an underlying diffuse encephalopathy and not to the hydrocephalus or to procedures related to the treatment of this disorder.     

甲状腺机能亢进与癫痫样发作(附2例报道)

目的探讨甲状腺机能亢进伴发癫痫样发作的临床特点和发病机制。方法通过中文医学期刊全文数据库及Medline检索到从1974年至今国内外相关的文献报道共17例,附我院癫痫中心2例报道。结果甲状腺机能亢进伴发癫痫样发作的临床表现有3种形式:(1)以痫样发作为首发症状出现;(2)痫样发作为继发临床症状;(3)癫痫患者合并甲亢时痫样发作加重。发作类型以全面性强直阵挛发作为主。结论(1)甲状腺机能亢进可引起脑损害而导致癫痫样发作,发病机制有待于进一步研究证实;(2)癫痫与甲亢可能存在某些共同的免疫发病机制。