Event-related potentials (P300) and EEG activity in childhood partial epilepsy

P300 development from infancy to adolescence

This article provides an overview of P300 research from infancy through adolescence. First, a brief historical overview is provided highlighting seminal studies that began exploration of the P300 component in developmental groups. Overall, these studies suggest that the P300 can be detected in children and appears to reflect similar cognitive processes to those in adults; however, it is significantly delayed in its latency to peak. Second, two striking findings from developmental research are the lack of a clear P300 component in infancy and differential electrophysiological responses to novel, unexpected stimuli in children, adolescents, and adults. Third, contemporary questions are described, which include P300-like components in infancy, alteration of P300 in atypically developing groups, relations between P300 and behavior, individual differences of P300, and neural substrates of P300 across development. Finally, we conclude with comments regarding the power of a developmental perspective and suggestions for important issues that should be addressed in the next 50 years of P300 research.

Application of the P300 Event-Related Potential in the Diagnosis of Epilepsy Disorder: A Review

Epilepsy is one of the most serious chronical neurological disorders, affecting more than 50 million people worldwide. It can be defined as a spectrum disorder, and patients with epilepsy possess abnormalities in cognitive functions. A number of factors can cause cognitive dysfunctions in epileptic syndromes, including etiology, the age of onset, type of seizure and severity, duration, and antiepileptic drugs. Event-related potentials (ERPs) are very useful clinical and research instruments to evaluate cognitive function in patients with neuropsychiatry disorders. Event-related potentials directly reflect cortical neuronal activity and provide a particular level of temporal resolution. Among various ERP components, the P300 is the most important component for assessing cognitive processes such as attention, working memory, and concentration. Numerous studies have reported the abnormalities in amplitude or latency of P300 component of ERP in epileptic patients, and these abnormalities are indicative of cognitive dysfunction. Therefore, the purpose of this review is to consolidate the existing literature in connection with the use of P300 in epileptic patients.

Physical Feature Encoding and Word Recognition Abilities Are Altered in Children with Intractable Epilepsy: Preliminary Neuromagnetic Evidence

Objective evaluation of language function is critical for children with intractable epilepsy under consideration for epilepsy surgery. The purpose of this preliminary study was to evaluate word recognition in children with intractable epilepsy by using magnetoencephalography (MEG). Ten children with intractable epilepsy (M/F 6/4, mean ± SD 13.4 ± 2.2 years) were matched on age and sex to healthy controls. Common nouns were presented simultaneously from visual and auditory sensory inputs in "match" and "mismatch" conditions. Neuromagnetic responses M1, M2, M3, M4, and M5 with latencies of ~100 ms, ~150 ms, ~250 ms, ~350 ms, and ~450 ms, respectively, elicited during the "match" condition were identified. Compared to healthy children, epilepsy patients had both significantly delayed latency of the M1 and reduced amplitudes of M3 and M5 responses. These results provide neurophysiologic evidence of altered word recognition in children with intractable epilepsy.

Electroencephalography in children with and without sensory processing disorders during auditory perception

OBJECTIVE

We sought to determine whether children with sensory processing disorder (SPD) differ from typically developing children on a neurophysiological measure, the P300 component of event-related potentials produced in response to brief auditory stimulation.

METHOD

We used electroencephalographic measures (i.e., N200 and P300 components) to examine auditory processing in 20 children with SPD and 71 typically developing children, ages 5-10 yr.

RESULTS

Children with SPD demonstrated significantly smaller P300 amplitudes and shorter N200 latencies than typically developing children. Brain activity correctly distinguished children with SPD from typically developing children with 77% accuracy. We also found a significant relationship between the neurophysiological measures and functional performance on sensory and motor tasks.

CONCLUSION

This study presents empirical evidence that children with SPD display unique brain processing mechanisms compared with typical children and, therefore, provide further evidence for the neural deviations associated with SPD.

Working memory in children with epilepsy: an event-related potentials study

PURPOSE

The aim of this study was to find out whether children with idiopathic epilepsy did show different cortical activation patterns compared to non-epileptic children during performance of a working memory task. To this end event-related potentials (ERPs) were measured during a visual 1-backmatching task. A quantitative analysis technique to analyze the ERP data, without any 'a priori' decisions on 'peak' presence, amplitudes or latencies, is used.

METHODS

46 children were tested (6-16 years old): 21 children with well-controlled "benign" epilepsy (benign rolandic epilepsy, n=9, idiopathic generalized epilepsy, n=12) and a control group of 25 non-epileptic children. Behavioral task performance and ERPs following both target and nontarget stimuli were compared across both study groups.

RESULTS

No differences were found in the number of omission errors or commission errors or in the reaction times between groups. However, ERPs following target stimuli showed significantly higher amplitude in the epilepsy group compared to the control group over frontal and central regions within the time window between 250 and 425 ms poststimulus, what coincides with the time window of target-nontarget stimulus discrimination.

DISCUSSION

Our study shows that children with benign, well-controlled epilepsy show a different cortical activation pattern during a visual working memory task. We hypothesize that they need more brain processing effort to achieve the same performance level as their age matched controls.

The relationship between fatigue and depression, and event-related potentials in epileptics

The aim of the present study was to establish the rate of fatigue and the relationship between fatigue, depression, and P300 in people with epilepsy. We compared Fatigue Severity Scale (FSS) and Beck Depression Inventory (BDI) scores and event-related potentials (ERPs) of people with epilepsy (n=73) with those of controls (n=31). The rate of fatigue was found to be 42.4%, and fatigue and depression were positively correlated. There was an interaction between fatigue and ERPs, but the effect of ERPs on fatigue was greater. While polytherapy was a major factor affecting ERPs, depression had no effect on ERPs in people with epilepsy. The data suggest that fatigue is an important finding and is strongly correlated with cognitive processes and depression. Polytherapy contributed to cognitive disturbances and, hence, fatigue, whereas depression had no effect on cognitive processes in people with epilepsy.

Cognitive functions evaluated by P300 and visual and auditory number assays in children with childhood epilepsy with occipital paroxysms (CEOP)

PURPOSE

This study was planned to evaluate cognitive functions, especially attention and immediate recall, in children with childhood epilepsy with occipital paroxysms (CEOP), by using P300 and neuropsychological tests, which included visual and auditory number assays. Thirty patients with CEOP, ages ranging from 5 to 17 years were enrolled in the study. Twenty-five healthy children were taken as the control group.

METHODS

Oddball paradigm was used in P300 recordings. The latency and the amplitude of the P300 wave recorded from Cz were taken into consideration. The neuropsychological test battery included visual and auditory number assays.

RESULTS

P300 latency was significantly longer in the CEOP group (p=0.014). The results of the visual and auditory number assay test showed significant decline in the patient group when compared with the normal controls.

CONCLUSIONS

Attention and immediate recall deficits as well as prolonged P300 latencies in children with CEOP can be due to an ongoing epileptic activity either influencing the whole brain or only the occipital lobe which can also be involved in the neuropsychological organization of the human cortex. Therefore, children with CEOP should be evaluated with more detailed neuropsychological tests for possible cognitive deficits.

Evaluating cognitive functions with visual and auditory number assays and P300 in children with epilepsy

This study was planned to evaluate cognitive functions, especially attention and immediate recall, in children with epilepsy by using P300 and neuropsychological tests, which included visual and auditory number assays. Fifty five patients with partial seizures, 45 patients with generalized seizures and 20 patients with intractable seizures were enrolled in the study. Twenty five healthy children were taken as the control group. The results were as follows: 1. P300 latencies were significantly longer in the intractable and partial groups when compared with the control subjects. 2. The duration of epilepsy, seizure frequency, cerebral imaging pathologies were not significantly correlated with delayed P300 latencies. 3. The results of the visual and auditory number assays test showed significant abnormalities when each of the three groups were compared with the normal controls. 4. Though some subgroups of the neuropsychological tests were correlated with the P300 latencies, an overall significant correlation was not present between them. So, we suggest that neuropsychological tests are more convenient for the assessment of cognitive functions in children with epilepsy than the P300 recordings.

Benigne epilepsietypische Potentiale des Kindesalters (Rolando-Spikes) - neurobiologische und neuropsychologische Befunde und ihre klinische Bedeutung in der Kinder- und Jugendpsychiatrie

Zusammenfassung: Einleitung: Die Rolando-Epilepsie ist das häufigste Epilepsie-Syndrom im Kindesalter. Sie ist elektroenzephalographisch charakterisiert durch das Auftreten von fokalen epilepsietypischen Potentialen, den sog. Rolando-Spikes (benigne epilepsietypische Potentiale des Kindesalters, BEPK). BEPK treten mit einer Häufigkeit von etwa 1,5 bis 2,4% bei Kindern auf; nur ein Zehntel erleidet epileptische Anfälle. Methoden: Diese Arbeit gibt einen Überblick über genetische, epidemiologische, radiologische, neurophysiologische, metabolische und neuropsychologische Befunde bei Kindern mit BEPK. Resultate: Der epileptologische Verlauf ist günstig, eventuell auftretende Anfälle sistieren spätestens mit der Pubertät; die epilepsietypischen Potentiale sind dann nicht mehr nachweisbar. Entgegen früherer Annahmen erstreckt sich das Symptomenspektrum über seltene Anfälle hinaus auf neuropsychologische Beeinträchtigungen und Verhaltensauffälligkeiten, auch bei Kindern ohne manifeste Anfälle. Der Einfluss der Rolando-Spikes auf die Entwicklung betroffener Kinder und ihr Verhalten ist unklar. Durch zwei Modelle wird versucht, den Zusammenhang von paroxysmaler EEG-Aktivität und neuropsychologischen Auffälligkeiten zu erklären. Das erste betrachtet die beobachtbaren Defizite als vorübergehende kognitive Beeinträchtigung infolge der epileptischen Aktivität; das zweite sieht als Ursache eine genetisch bedingte zerebrale Reifungsstörung mit enger Verwandtschaft zu Teilleistungsstörungen. Schlussfolgerung: Die Behandlungsnotwendigkeit neuropsychiatrischer Symptome bei Kindern mit BEPK ohne manifeste Anfälle wird derzeit kontrovers diskutiert.

P300 (Latency) Event-Related Potential: An Accurate Predictor of Memory Impairment

To determine if P300 latency changes precede and correlate with memory and mental status, patients (N=1506 aged 20–100 years) who received medical and psychiatric diagnoses (from 1997 to 2002), were assessed for P300 (N=1496), WMS-III (N=694), and MMSE (N=456). Patient and control groups included, a) normal WMS-III on all 4 subscales (N=36), b) normal WMS-III and MMSE (N=189) with subjective memory/mental status complaints, and c) medical patients with normal WMS-III and no memory complaints (N=205), and d) P300 control group without medical, psychiatric or memory problems for ROC.

Patients with impaired/borderline memory had a prolonged P300 latency (P<0.02) compared to age matched non-impaired controls; in patients with normal WMS-III/MMSE, with subjective mild memory/mental status impairment, P300 latency was prolonged compared to controls (P=0.0004). The P300 latency increased by 0.72ms per year (P=7.9×10−65) and voltage decreased by 0.03dV per year (P=6.7×10−10), and both parameters were linearly correlated with the age of the subjects.

Male subjects had an average voltage of 6.1dV and female 6.8dV(P=0.00009). Statistically, prolonged latency began at age range 41–50 (P=0.0002); reduced P300 voltage began at age range 51–60 (P=0.003). WMS-III memory decline for all measures began in females at age range 61–70 (P value at least=0.02) and for males at age range 61–80 (P=0.02). Prolonged P300 latency (P≤0.0001) and memory impairment (at least <0.02) were greater for females than males. MMSE memory decline, male and female, began at age range 81–90 (P value of at least 0.00007).

In our logistic regression model P300 latency was more predictive of WMS-III impairment than MMSE >24. In patients whose WMS-III score is impaired ≤69, or borderline ≤79 (P at least =0.004), a P300 latency more prolonged than the norm (≥300 + 30 + Age) identifies these patients, whereas a MMSE >24 failed. With the ROC curve, we confirmed that P300 latency could accurately identify borderline/impaired memory.