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1.
The cognitive deficit often associated with epilepsy is attributable to the presence and interaction of several factors but whether recurrent subclinical spike-wave discharges interfere with cognitive development is not yet clear. In the present study, the presence of subclinical discharges proved to be significantly associated with lower than average Full-Scale Intelligence Quotient (IQ), Verbal IQ and Performance IQ scores (Wechsler Intelligence Scale for Children) in comparison with patients not presenting EEG abnormalities during test. These findings confirm the adverse effect both of generalized and focal EEG epileptiform abnormalities, even if unaccompanied by overt seizures.  相似文献   

2.
Binnie CD 《Lancet neurology》2003,2(12):725-730
Epileptiform EEG discharges are not confined to people with epilepsy, and their frequency is only weakly related to severity. A fundamental principle of EEG practice is, therefore, to avoid overinterpretation of epileptiform activity. Epileptiform discharges not accompanied by obvious clinical events are generally regarded as subclinical or interictal. However, in many patients sensitive methods of observation, notably continuous psychological testing, show brief episodes of impaired cognitive function during such discharges. This phenomenon of transitory cognitive impairment (TCI) is found in about 50% of patients who show discharges during testing. TCI is not simple inattention. The effects are material and site specific: lateralised discharges are associated with deficits of functions mediated by the hemisphere in which the discharges occur. Conversely, specific tasks can activate or suppress focal discharges over the brain regions that mediate the cognitive activity in question. TCI clearly contributes to the cognitive problems of some people with epilepsy and may cause deficits that pass unrecognised. TCI is demonstrable in many cases of benign partial epilepsy of childhood, a disorder once thought to have no adverse psychological effects. TCI can contribute to abnormalities of psychological test profiles and interferes with daily tasks, such as reading and driving. In children it may be associated with behavioural disorders. An important practical issue is whether TCI materially impairs psychosocial function and, if so, whether drug treatment is desirable or effective. Uncontrolled reports and two preliminary randomised controlled trials of antiepileptic treatment of TCI have suggested that suppression of discharges is associated with significant improvement in psychosocial function.  相似文献   

3.
Seneviratne U  Cook M  D'Souza W 《Epilepsia》2012,53(2):234-248
Idiopathic generalized epilepsy (IGE) is classified into several subsyndromes based on clinical and electroencephalography (EEG) features. The EEG signature of IGE is bisynchronous, symmetric, and generalized spike-wave complex; although focal, irregular, and so called "fragments" of discharges are not uncommon. Other characteristic EEG features include polyspikes, polyspike-wave discharges, occipital intermittent rhythmic delta activity, and photoparoxysmal response. Both human and animal data suggest involvement of the thalamus and the cortex in the generation of spike-wave discharges in IGE. Circadian variations of generalized epileptiform discharges are well described, and these can be useful in diagnostic confirmation. Those discharges tend to occur more often after awakening and during cyclic alternating pattern phase-A of non-rapid eye movement sleep. Activation procedures such as hyperventilation, intermittent photic stimulation, eye closure, and fixation-off are useful techniques to increase the yield of both interictal and ictal EEG abnormalities. Although not in routine use, specific triggers such as pattern stimulation and cognitive tasks may also be of value in eliciting rare reflex seizure-related EEG abnormalities. Variations of EEG abnormalities are evident between different electroclinical syndromes. EEG is also affected by certain external as well as internal factors, which should be borne in mind when interpreting EEG studies in IGE.  相似文献   

4.
The possible effects of subclinical epileptiform EEG discharges on educational skills have been studied. Twenty children with proven or suspected epilepsy and known subclinical EEG discharges underwent telemetric EEG and video monitoring during standard tasks of reading, mental arithmetic and manual dexterity, and at rest. The discharge rate was significantly lower at rest than during execution of a task. For both reading and arithmetic, the discharge rate was higher when the child was presented with material appropriate to his own level of ability than when easier or more difficult material was given. High discharge rates were associated with low test performance particularly for arithmetic. Reading speed was significantly increased during the discharges, but overall reading efficiency was significantly reduced with respect to the non-discharge condition. The decrement of reading efficiency was greater for longer than for shorter discharges. The findings confirm that otherwise subclinical EEG discharges may be accompanied by momentary impairment of scholastic skills. The interaction between discharges and cognitive function is, however, complex and the nature and level of difficulty of the task in turn affects the rate of EEG discharge.  相似文献   

5.
The occurrence of transitory cognitive impairment during diffuse subclinical electroencephalographic (EEG) discharges has been widely documented but the role of the parameters influencing the cognitive performance and the involvement of motor or verbal response in the tasks used is still under debate. Fifteen patients suffering from primary generalized epilepsy with frequent bisynchronous EEG epileptic bursts underwent a shape recognition task during EEG monitoring. The test sequence was as follows: memorandum, pause, and multiple choice set. After pressing the response button, the patient was asked to confirm the choice verbally. The following parameters were considered: geometrical complexity of the shape, chronological position of the burst occurring during the single test, and the duration of discharge ranging from 1 to 3 s. Results showed a significant increase in incorrect responses during the test when discharges occurred, with more errors occurring for difficult than for easy shapes. Neither the discharge position nor the duration of the epileptic burst influenced the performance. Diffuse epileptic activity of short duration produced selective effects on the cognitive process regardless of the motor component of the response.  相似文献   

6.
Altered cognitive functioning has often been reported in patients with epilepsy. In our study we looked for quantitative correlation between the recurrence of Subclinical Spike-and-Wave Discharges (SSWD) during EEG recording, the scores on the intelligence test (WISC) and the electro-clinical characteristics of 29 epileptic children with subclinical discharges of generalized spike-and-wave complexes. In our sample we found a below-normal mean IQ, with greater impairment on performance than on verbal tasks. No clear quantitative correlation was found between the weighted scores on the various subtests and the "time density" of the spike-and-wave complexes. These findings suggest that the SSWD interfere with cognitive development (mainly with visuo-spatial and sensorimotor coordination abilities) and selectively impair some of the functions involved in the cognitive processes.  相似文献   

7.
Landau-Kleffner Syndrome: A Clinical and EEG Study of Five Cases   总被引:19,自引:4,他引:15  
In five children with normal initial psychomotor development, a Landau-Kleffner syndrome appeared at age 3-7 years. No neuroanatomic lesions were noted. Aphasia and hyperkinesia were isolated in three patients and associated with global regression of higher cortical functions in one patient. Massive intellectual deterioration and psychotic behavior were associated with transient aphasia in one patient. The epilepsy (focal motor and generalized tonic-clonic seizures, subclinical EEG focal seizures during sleep, and atypical absences) always regressed spontaneously or with antiepileptic drug (AED) treatment. The EEG in waking patients showed focal and generalized spike-wave discharges on a normal background rhythm. Discharge topography and pattern changed frequently. During sleep, discharges always increased. At some time during syndrome development, all patients had bilateral spike-waves for greater than 85% of the sleep period, while at other times the discharges were discontinuous or continuous but focal or unilaterally hemispheric. Discharge topography and abundance changed from night to night. The abnormal EEG and the impaired higher functions developed and regressed together, but not with strict temporal correlation. Our own experience suggests that the Landau-Kleffner syndrome and epilepsy with continuous spike-wave activity in slow-wave sleep cannot be clearly differentiated. They may be different points on the spectrum of a single syndrome.  相似文献   

8.
In this prospective, open, clinical comparative study we analyzed impairments of cognitive activation occurring during, immediately before and immediately after epochs with epileptiform EEG discharges of 3 seconds or longer, in an attempt to establish whether cognitive slowing occurs in direct association with an epoch with epileptiform EEG discharges and whether cognitive impairments precede or follow such an epoch. All children were assessed with EEG/video (Brainlab) simultaneously with computerized neuropsychological testing (FePsy): a test for cognitive activation (simple visual and auditory reaction time measurement). Thirty-seven epochs with epileptiform EEG discharges without clinical signs of a seizure (subclinical epileptiform EEG discharges) were evaluated. The results showed a statistically significant and clinically relevant slowing (35% compared to the overall reaction time), occurring during the epoch with epileptiform EEG discharges (repeated measurement analysis of variance p = < .05; df = 3; F-value: 3.293). No statistically significant slowing was found for the periods 'post-discharge' or 'pre-discharge'. Type of discharge was important and effects on cognitive activation were found exclusively for generalized discharges. This effect was, however, also seen in the remaining period, outside the 'peri-discharge' periods and thus seemed to represent a more general effect of the type of epilepsy on cognitive activation. Our results show that the acute effect of short epileptiform EEG discharges (duration 4.14 sec; sd 1.38) may be impressive, causing impairment (slowing) of cognitive activation. This effect was limited to generalized discharges. This effect was not observed for focal discharges, even during longer periods with discharges. However, it is reassuring that this impact on cognitive activation is limited to the actual period in which the discharges occur and does not have 'post-discharge' effects. The risk of accumulating effects that may have longer-lasting repercussions on higher-order cognitive functions therefore seems to be negligible.  相似文献   

9.
Background: Spikes and spike-and-wave discharges on the EEG of children are a strong biomarker of epilepsy. There is increasing evidence that these EEG abnormalities also impair brain function and result in transitory cognitive impairment. Studies in animal models have shown that EEG spikes alters single cell firing and that such impairment in firing may extend beyond the duration of the spike-and-wave discharge. Whether interictal epileptiform discharges have lasting effects on EEG activity in humans is not known. Methods and Results: The EEGs of 60 consecutive children with focal or interictal spike-and-wave discharges were evaluated using power spectral analysis to determine if there were any changes in power spectra from before to after the interictal abnormalities. Neither focal spike-and-wave nor generalized spike-and-wave discharges had any effect on the EEG frequency or spectral power following the discharge. Conclusion: While interictal EEG discharges temporarily alter neural activity during the duration of the spike-and-wave discharge, there is no evidence that alterations of spectral power continue beyond the duration of the interictal discharge. The effects of interictal activity on EEG rhythms therefore appear to be quite transient and confined to the duration of the interictal discharge.  相似文献   

10.
Interactions of epileptiform EEG discharges and cognition   总被引:13,自引:0,他引:13  
Interactions of subclinical epileptiform EEG discharges and cognitive functioning were studied in 91 patients with epilepsy, under video monitoring, to exclude overt clinical ictal phenomena during the investigations. A short-term memory test was presented as an engaging television game, in two versions, using spatial, or verbal material. Transitory cognitive impairment (TCI) was demonstrated during EEG discharges, either generalised or focal, in half the patients. Right-sided discharges were associated with impairment of the spatial task and left-sided with errors on the verbal version. TCI was demonstrable only when the discharge occurred during presentation of the material to be recalled. Increasing task difficulty, up to the patients' limit of performance, was associated with increasing susceptibility to TCI. Sixteen patients showed a significant effect of task on discharge rate, but in some this increased during the stimulus and in others while responding. There are thus complex interactions of epileptiform EEG activity on cognitive function and vice versa.  相似文献   

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