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.     

Modality dependent changes in event-related potentials correlate with specific cognitive functions in nondemented patients with Parkinson's disease

Summary The relationship between event-related potentials (ERPs) and cognitive functioning was studied in patients with Parkinson's Disease (PD) but without dementia. Auditory and visual stimuli were used; 30 subjects participated in the auditory study and 20 in the visual study. Patient groups did not differ with respect to gender, age, education, illness duration, and level of cognitive functioning. Visual stimuli were 2.3 cpd sinusoidal grating patterns randomly presented in an oddball paradigm (oblique vs. vertical spatial orientation). Auditory stimuli were tones presented at 70dB SPL at a rate of 1.1/second, also using the oddball paradigm (1.5K vs. 1K tones). All patients were given neuropsychological tests to measure verbal fluency, memory, visual spatial perception, and abstract reasoning. P300 and N200 abnormalities correlated with a number of these measures, such that longer ERP latencies were related to lower scores on tests of cognitive functioning. Patterns of results suggest that auditory and visual ERPs correlate with different subsets of neuropsychological functions in nondemented PD patients and that N200 may provide a new metric for clinical use.     

Higher brain dysfunction in benign childhood epilepsy with centrotemporal spike and atypical benign partial epilepsy of childhood

Although some recent studies have reported various cognitive impairments and behavioral disorders in children having benign childhood epilepsy with centrotemporal spike (BCECT), it is still commonly believed that BCECT does not cause any definite neuropsychological impairment. In addition, reported impairments range over various cognitive functions, and there is no general agreement on this issue. We performed detailed neuropsychological tests in 17 children with BCECT and analyzed the profiles of their subtests. Atypical benign partial epilepsy of childhood (ABPE) is a type of BCECT in which patients have minor generalized seizures and their EEGs show continuous spike-waves during sleep. We also performed the same tests in five patients with ABPE, and compared the results in the two groups. Neuropsychological tests performed are as follows: Kaufman assessment battery for children (K-ABC), Wechsler intelligence scales for children-revised (WISC-R), Illinois test of psycholinguistic abilities (ITPA), Benton visual retention test (BVRT), Token test, calculation, figure copying task, letter copying task, line bisection task, and line cancellation task. Mental processing composite of the K-ABC and FIQ of the WISC-R were within normal limits in all children with BCECT and ABPE, but were generally lower in ABPE than in BCECT. On the other hand, the profiles of subtests of ITPA in children with BCECT revealed the significant feature of the lower scores on verbal expression (p = 0.013) and auditory sequential memory (p = 0.035). Considering the normal scores in the elementary cognitive functions, such as visual and verbal functions and long-term memory, disturbance in the process of executive functions such as flexibility, fluency, and working memory could cause this characteristic profile. ABPE also showed the similar profile in the subtests of ITPA to that of BCECT. It is likely that both groups of children share the common cognitive dysfunction.     

Effect of vagal nerve stimulation on auditory and visual event-related potentials

Chronic unilateral vagal nerve stimulation (VNS) has been recently introduced into the therapy for intractable epileptic seizures. Its effect on cognitive functions in VNS-treated patients remains controversial. The aim of the present study was to evaluate the possible impact of therapeutic VNS on cognitive functions by means of event-related potentials analysis. Ten patients with medically intractable epilepsy, who had been implanted with VNS devices, participated in the study. Auditory and visual event-related potentials (ERPs) were repeatedly recorded, first just before the implantation of VNS devices, and then again 3-6 months after the device activation. The effect of lower intensity stimulation on the P3 component of ERPs was assessed. No significant differences were found in auditory ERPs; the latencies of P3 as well as N2/P3 peak-to-peak amplitudes were virtually identical. The same was true for mean P3 latencies of visual ERPs. However, higher visual N2/P3 peak-to-peak amplitudes were observed in the responses to targets that followed VNS, with a significant finding at the electrodes investigated. When comparing the effect of VNS on visual N2/P3 amplitude in each electrode separately, the most expressive differences were found in the frontal region. This observation supports the theory of a possible positive effect of low-intensity VNS on the cognitive functions.     

Motor and cognitive functions in newly diagnosed adult seizure patients before antiepileptic medication

OBJECTIVE: Motor and cognitive functions in patients with partial or generalized onset of seizures were evaluated prior to the administration of antiepileptic medication. MATERIAL AND METHODS: Motor function, attention and memory of 52 consecutive newly diagnosed adult patients with partial or generalized seizures were assessed with neuropsychological tests. RESULTS: Patients with partial onset of seizures did not differ from patients with generalized seizures in tests of motor function or attention, nor in tests of learning and memory. Compared to controls patients with epilepsy performed significantly worse on visual motor tasks, mental flexibility and in delayed visual memory. Within the patient group as a whole lower education, higher age and symptomatic epilepsy with more abnormal CT scan findings tended to associate with worse performance in tests of concentration and mental flexibility and tests of memory. CONCLUSION: These findings indicate that newly diagnosed adult patients with partial or generalized onset of seizures prior to treatment with antiepileptic medication experience some problems in visual motor tasks, mental flexibility and memory even without the numerous risk factors for cognitive deficits in epilepsy. In newly diagnosed patients with epilepsy as a whole symptomatic etiology was associated with somewhat more pronounced cognitive problems.     

Cognitive outcome of parietooccipital resection in children with epilepsy

Purpose: We followed the neuropsychological development of five children who underwent unilateral neurosurgery of the occipitoparietal lobes as a treatment for epilepsy caused by a developmental lesion (cortical dysplasia). Methods: The follow‐up period ranged from 3–7 years postsurgery. Results: Two participants had a verbal intelligence quotient (IQ) >100 and three had a verbal IQ between 65 and 80. All five children had abnormal nonverbal IQ and exhibited deficits related to visual attention, object recognition, and praxis. Nevertheless, our results suggest that brain plasticity after parietooccipital epilepsy surgery in young children allows for a schooling level of cognitive skills such as reading and arithmetic. Discussion: Although recovery for visual perceptual cognition was more limited than for verbal functions, long‐term neuropsychological outcomes showed that early surgery for epilepsy offers the possibility of optimizing cognitive outcomes in children with posterior intractable epilepsies.     

Pre- and Postoperative Auditory Event-Related Potentials in Temporal Lobe Epilepsy

We studied auditory event-related potentials (ERPs) in 11 surgically treated patients with intractable temporal lobe epilepsy (TLE) pre- and postoperatively. ERPs through sphenoidal electrodes (Sp1-T3, Sp2-T4) provided clinically relevant and correctly lateralizing electrophysiologic evidence of temporal lobe dysfunction in 9 of 11 patients, confirmed by EEGs, electrocorticograms, neuroradiologic, and neuropsychological results, and clinical follow-up. Lateralizing asymmetries were noted in P300 amplitude, but latencies were prolonged bilaterally. Sphenoidal ERPs might serve as a new functional indicator of temporal lobe dysfunction in patients evaluated for epilepsy surgery.     

The auditory P300 correlates with specific cognitive deficits in Parkinson's disease

Summary An abnormally prolonged latency of the P300 event-related potential has been reported in several types of dementing illnesses, including Parkinson's disease (PD). While some PD patients have dementia, a significant number of PD patients have less severe cognitive impairments. We examined the relationship between the auditory P300 and a neuropsychological battery of 11 tasks in 43 PD patients. The quantitative relationship between the individual neuropsychological measures and the P300 was examined using partial correlation and analysis of covariance techniques which controlled for age, education, and illness duration. The strongest correlations were between P300 and both shortterm memory and visual perception. Global cognitive deficits do not appear to relate to the abnormal P300 responses in PD: instead, specific aspects of cognitive decline accounted for the electrophysiological abnormalities. An abnormally long or absent P300 correlated with deficits on select cognitive tasks: those involving memory, visual perception, and abstract reasoning. The interactions between anatomical and neurochemical abnormalities in PD are discussed in light of the pattern of deficits seen in this study.     

Long-latency auditory event-related potentials in epilepsy

Long latency auditory event-related potentials have been shown to change in patients with cerebral dysfunction. Some seizure patients with no evidence of brain damage or mental retardation show altered interictal cognitive and memory function. Long-latency auditory event-related potentials to tone stimulation were recorded in nineteen control subjects and seventeen patients with complex partial or partial and secondarily generalized seizures who had no evidence of brain damage, retardation, or drug intoxication, and whose seizures were controlled when studied. The latencies of N2 and P3 components were significantly longer in seizure patients than control subjects, and the P3 waveform was significantly greater in amplitude in epileptics. These findings suggest that cognitive event-related potentials are affected by partial epilepsy. The changes may be related to the recently reported involvement of the hippocampus in ERP generation, or to loss or alteration of modulatory functions, possibly cholinergic in nature, in the temporal lobe consequent upon epileptogenesis.     

Double-blind placebo-controlled, neuropsychological and neurophysiological investigations with oxiracetam (CGP 21690E) in memory-impaired patients with epilepsy

A double-blind placebo-controlled between-patient study was carried out to assess the effects of oxiracetam (CGP 21690E) on memory function in patients with epilepsy. During a 12-week period, either oxiracetam (800 mg t.i.d.) or placebo was given to 30 patients. Twenty-four of the patients had a partial epilepsy. Most patients were on monotherapy carbamazepine. Effect of oxiracetam on memory and related cognitive functions were assessed, using a computerized neuropsychological testing method, while concomitant electrophysiological changes were investigated with routine EEG registration, power spectrum analysis and auditory evoked event-related potentials (P300). Subjective evaluation of well-being was quantified with a mood rating scale. The results did not show any meaningful changes in memory function. This finding is in line with the subjective patient reports and the P300 measures.     

Benign childhood epilepsy with occipital paroxysms: neuropsychological findings

Benign childhood epilepsy with occipital paroxysms is classified among childhood benign partial epilepsies. The absence of neurological and neuropsychological deficits has long been considered as a prerequisite for a diagnosis of benign childhood partial epilepsy. Much evidence has been reported in literature in the latest years suggesting a neuropsychological impairment in this type of epilepsy, particularly in the type with Rolandic paroxysms. The present work examines the neuropsychological profiles of a sample of subjects affected by the early-onset benign childhood occipital seizures (EBOS) described by Panayotopulos. The patient group included 22 children (14 males and 8 females; mean age 10.1+/-3.3 years) diagnosed as having EBOS. The patients were examined with a set of tests investigating neuropsychological functions: memory, attention, perceptive, motor, linguistic and academic (reading, writing, arithmetic) abilities. The same instruments have been given to a homogeneous control group as regards sex, age, level of education and socio-economic background. None of the subjects affected by EBOS showed intellectual deficit (mean IQ in Wechsler Full Scale 91.7; S.D. 8.9). Results show a widespread cognitive dysfunction in the context of a focal epileptogenic process in EBOS. In particular, children with EBOS show a significant occurrence of specific learning disabilities (SLD) and other subtle neuropsychological deficits. We found selective dysfunctions relating to perceptive-visual attentional ability (p<0.05), verbal and visual-spatial memory abilities (p<0.01), visual perception and visual-motor integration global abilities (p<0.01), manual dexterity tasks (p<0.05), some language tasks (p<0.05), reading and writing abilities (p<0.01) and arithmetic ability (p<0.01). The presence of cognitive dysfunctions in subjects with EBOS supports the hypothesis that epilepsy itself plays a role in the development of neuropsychological impairment. Supported by other studies that have documented subtle neuropsychological deficits in benign partial epilepsy, we stress the importance of reconsidering its supposed "cognitive benignity", particularly in occipital types.     

P300 latencies in epileptic children: the differences among various epileptic syndromes

Auditory event-related potentials (ERPs) were recorded from 129 epileptic children of 5 to 20 years of age. To clarify the developmental changes in each of the epileptic syndromes, P300 latencies of ERPs were examined. ERPs were elicited with the auditory oddball paradigm. P300 detection was occasionally difficult in epileptic children. Mean P300 latency in epileptic children (375 +/- 39.7 msec) was significantly prolonged compared with that in normal control children. (355 +/- 39.1 msec). P300 latencies in the children with symptomatic partial epilepsies were prolonged and were not recognized to be shortened with age. In the idiopathic partial epilepsies of 5 to 12 years of age, P300 latencies showed almost the same values with those in the normal children. However, in the idiopathic partial epilepsies of 13 to 15 years of age, P300 latencies were significantly prolonged compared with those in normal children and there were no difference in P300 latencies with other epileptic syndromes. P300 latencies in idiopathic generalized epilepsies showed intermediate values between that in symptomatic partial epilepsies and idiopathic partial epilepsies. Each epileptic syndrome showed different developments in P300 latencies with age. This results suggests that the development and the disturbance of cognitive functions differ among the epileptic syndromes.     

Cognition in Parkinson disease: An event-related potential perspective

Auditory event-related potentials (ERP) elicited in a target detection stimulus paradigm and pattern-shift visual ERPs were studied in 20 male patients with idiopathic Parkinson disease (PD) and 20 age-matched normal controls. Patients showed significantly increased latencies for both the P200 and P300 components of the auditory ERP. Patients and controls showed no significant differences in latency of the visual ERP but patients showed significantly decreased amplitude. Only one of five neuropsychological measures, the Symbol Digit Modalities test (SDMT), showed a significant negative correlation with P300 latency. The significant association between the two measures that showed impairments in the PD patients (P300 latency and SDMT scores) suggested that these measures reflect a common, disrupted aspect of cognitive function in PD.     

Brain oscillatory EEG event-related desynchronization (ERD) and -sychronization (ERS) responses during an auditory memory task are altered in children with epilepsy.

PURPOSE: Children with epilepsy are in risk for cognitive impairment, but reliable methods, other than neuropsychological testing, to verify such a decline are few. The purpose of this study was to assess the effect of infrequent seizures on cognitive skills in children with non-symptomatic focal epilepsy taking antiepileptic medication but still having infrequent seizures. METHODS: EEG (electroencephalogram) brain electric oscillatory responses of the 4-6Hz, 6-8Hz, 8-10Hz and 10-12Hz EEG frequency bands were studied. These responses, assessed by means of the event-related desynchronization (ERD) and synchronization (ERS) method, were recorded in 6 children with epilepsy (mean age 11.3 years) and in 11 control children (mean age 12 years) while they performed an auditory memory task. All subjects also underwent a comprehensive neuropsychological test battery. RESULTS: The differences in the 4-6Hz ERD/ERS responses between encoding and recognition were smaller in the children with epilepsy as compared to those of the control children. In the 6-8Hz frequency band, the responses of the two groups dissociated most notably in the frontal electrodes. No statistically significant differences in the alpha frequency range (8-12Hz) were observed between the groups. CONCLUSIONS: Significant alterations in the lower EEG frequency (4-8Hz) ERD/ERS responses in children with epilepsy during auditory memory processing, as compared to age-matched, healthy children may suggest that seizures affect memory and underlying brain processes, indexed also by poorer performance particularly in neuropsychological subtests related to language functions.     

Cognitive skills in children with intractable epilepsy: comparison of surgical and nonsurgical candidates

PURPOSE: To compare neuropsychological performance of two groups of children with intractable epilepsy: those who are surgical candidates, and those who are not. METHODS: Intelligence, verbal memory, visual memory, academic skills, and sustained attention were measured in children aged 6-18 years. The effects of number of antiepileptic drugs (AEDs), seizure frequency, age at seizure onset, and duration of seizure disorder were examined. RESULTS: Both groups had high rates of impairment. Group differences were found only on the verbal memory task. Children who experienced seizures in clusters had higher IQ, reading comprehension, and arithmetic scores. Age at seizure onset and proportion of life with seizures were related to IQ. Performance did not vary with AED monotherapy versus polytherapy. CONCLUSIONS: Few differences exist in cognitive performance between children with intractable seizures who are and those who are not surgical candidates. These findings suggest that children who are not surgical candidates can serve as good controls in studies on cognitive outcome of surgery.     

Visual and auditory event-related potentials in sporadic amyotrophic lateral sclerosis.

OBJECTIVES: To investigate the relationship between amyotrophic lateral sclerosis (ALS) and cognitive function by means of oddball event-related potentials (ERPs) and to determine the usefulness of this methodology in the cognitive status assessment of physically disabled patients.METHODS: Visual and auditory oddball ERPs were recorded in 16 consecutive sporadic ALS patients. A comprehensive battery of neuropsychological (NP) tests assessed intelligence, executive functions, attention, memory, word fluency, visuo-motor and visual-constructive skills.RESULTS: All patients performed visual and auditory ERPs and 75% of cases showed abnormal N200 and/or P300 waves. Ten patients (62.5%) carried out the entire psychometric evaluation with significant impairment on tests of executive function and attention. A significant correlation between delayed visual (P<0.04) and auditory (P<0.04) P300 latency and impaired NP tests was found.CONCLUSIONS: In agreement with literature data, our findings confirm the hypothesis of cognitive impairment in ALS patients especially on attention and executive functions suggesting a more extensive degeneration beyond the motor areas. ALS causes severe physical disabilities and such a condition may interfere with NP testing. Thus, the P300 seems to be a useful tool for the assessment of cognition and attention when severe physical deficits are present.     

Auditory and visual P300 cognitive evoked responses in patients with COPD: relationship to degree of pulmonary impairment.

Twenty-two subjects with documented COPD and no other significant illnesses were studied to assess the effect of varying degrees of COPD on cognitive P300 auditory and visual evoked potentials. The severity of COPD was determined by spirometry with assessment of FEV1, FVC, and FEV1/FVC. Auditory P300 latency was significantly correlated with the FEV1/FVC ratio (Pearson Product Moment correlations r = -.56, N = 20, probability level = 0.1), indicating that increasingly severe airflow impairment is associated with longer auditory P300 latencies. There was no significant association of FEV1/FVC with visual P300 latency or with auditory or visual evoked potential amplitude measures. Progressive impairment of the auditory P300 evoked potential latency occurs with increasing severity of COPD. This impairment is present even in patients with mild COPD, suggesting some degree of accompanying cognitive decline early in the course of COPD with worsening as the disease progresses.     

Neurocognitive development of children with congenital unilateral brain lesion and epilepsy

The aim of this study was to specify the neuropsychological deficits characteristic of children with unilateral non-progressive brain lesion. In order to assess these specific functions, we used a comprehensive model of congenital hemiparesis with partial epilepsy and newly diagnosed partial epilepsy without hemiparesis. The neuropsychological examination was performed using the NEPSY test battery on 44 children aged from 4 to 9 years. The children were divided into three groups: 18 children suffering from congenital hemiparesis with chronic partial epilepsy, 12 children with newly diagnosed partial epilepsy prior to anti-epileptic treatment, and 14 healthy controls matched by sex, age, and socioeconomic status. Children with congenital hemiparesis and epilepsy had a more clearly expressed cognitive dysfunction, especially in language, visuo-perceptual and memory tasks, than children with newly diagnosed partial epilepsy. The profile of cognitive weakness appears to be diffuse and quite similar in both groups, and it did not demonstrate a clear effect of lateralization, according to the side of epileptic electroencephalogram discharges. Children within both groups are likely to have a high risk of developing attention, phonological, visuo-perceptual, and memory deficits in their life. Especially interesting and surprising was the fact that the newly diagnosed epilepsy group demonstrated impairment not only in attention, visuo-perceptual and short-term memory skills, but also in auditory perception, lexical function, and the comprehension of speech. Therefore, it is recommended that children with epilepsy would undergo neuropsychological examination in order to assess their cognitive abilities.     

Changes in auditory P300 event-related potentials and brainstem evoked potentials in diabetes mellitus

To investigate the influence of diabetes mellitus on higher cognitive functions electrophysiologically, we studied auditory P300 event-related potentials (P300) in 40 NIDDM patients, taking into account wave I-V latencies (I-V) in auditory brainstem evoked potentials, clinical parameters and head MRI findings. Compared with 20 controls, diabetics had significantly longer P300 and I-V latencies. P300 latencies in diabetics correlated with neither I-V. HbA₁, blood glucose levels, nor disease duration. Of the 13 diabetics investigated neuroradiologically, four had lacunar infarcts with prolonged electrophysiological values. The remaining nine had normal MRI scans, but their physiological parameters were still significantly longer than those of controls. These findings suggest that NIDDM can independently alter higher cognitive and the central auditory pathway functions. Our data also suggest that these alterations occur regardless of the recent metabolic derangement and disease duration. Cerebrovascular ischemia, if present, also appears to contribute in part to cognitive alterations.     

Event-related potentials and neuropsychological tests in obsessive-compulsive disorder

OBJECTIVE: Previous studies have provided evidence from event-related potentials (ERPs) and neuropsychological testing of abnormal cognitive processing in obsessive-compulsive disorder (OCD). The aim of this study was to further characterize the cognitive functions of the patients with OCD by utilizing ERPs and neuropsychological tests. METHODS: ERPs were recorded in a group of 31 drug-free OCD patients without depression and 30 normal controls following verbal auditory stimuli using an oddball paradigm. The specific neuropsychological tests administered to assess cognitive functions in all participants were the Stroop Test, Trail Making Test, Design Fluency Test, Controlled Word Association Test (Verbal Fluency test). RESULTS: The patient group showed shorter P300 duration compared to normal controls. In neuropsychological tests, no significant differences were found between the two groups. Negative correlations between Stroop duration and P300 amplitudes in occipital, parietal, and temporal anterior regions were observed. CONCLUSION: Shorter P300 duration may indicate an acceleration in the P300 process, and speeding of cognitive processing, dysfunction of cortico-subcortical circuits, or some combination of all of the above.