Photosensitivity in Relation to Epileptic Syndromes: A Survey from an Epilepsy Center in Japan

PURPOSE: We examined the incidence and distribution of photosensitivity among the different age groups and different types of epilepsies and epileptic syndromes. Furthermore, we considered the influence of ethnic and geographic factors on the incidence of photoparoxysmal response (PPR) in epilepsy patients. METHODS: We analyzed the responses to intermittent photic stimulation (IPS) by using a Grass PS22 or PS33 photic stimulator for in 2,187 unselected patients with epilepsy who were treated in our center. RESULTS: The classic PPR was elicited in 37 (1.7%) patients. The mean age of these 37 patients was 17.0 years. The subpopulation of patients having PPR included 2.0% of all patients with symptomatic generalized epilepsy. 5.6% (p < 0.01) of those with idiopathic generalized epilepsy, 0.7% of those with symptomatic localization-related epilepsy, and 2.9% of those with undetermined epilepsy. PPR accounted for 17.4% (p < 0.01) of the patients with juvenile myoclonic epilepsy, 7.6% (p < 0.01) of those with grand mal on awakening, and 6.1% (p < 0.01) of those with symptomatic occipital lobe epilepsy. The incidence of PPR increased in patients up to age 15 years, and suddenly decreased after age 20 years. CONCLUSION: The present study presents the first report from eastern Asia, analyzing the incidence of PPR with a restricted definition comparable to the other studies, and the rate of PPR was relatively low compared with the studies performed in the European countries. We could confirm the clear relation between age and positive PPR.     

Enhanced frontocentral EEG connectivity in photosensitive generalized epilepsies: a partial directed coherence study

Purpose: Photosensitive epilepsy (PSE) is the most common form of reflex epilepsy presenting with electroencephalography (EEG) paroxysms elicited by intermittent photic stimulation (IPS). To investigate whether the neuronal network undergoes dynamic changes before and during the transition to an EEG epileptic discharge, we estimated EEG connectivity patterns in photosensitive (PS) patients with idiopathic generalized epilepsy. Methods: EEG signals were evaluated under resting conditions and during 14 Hz IPS, a frequency that consistently induces photoparoxysmal responses (PPRs) in PS patients. Partial directed coherence (PDC), a linear measure of effective connectivity based on multivariate autoregressive models, was used in 10 PS patients and 10 controls. Anterior versus posterior (F3, F4, C3, C4, and P3, P4, O1, O2) and interhemispheric connectivity patterns (F4, C4, P4, O2, and F3, C3, P3, O1) were estimated with focus on beta and gamma band activity. Key Findings: PDC analysis revealed an enhanced connectivity pattern in terms of both the number and strength of outflow connections in the PS patient group. Under resting condition, the greater connectivity in the PS patients occurred in the beta band, whereas it mainly involved the gamma band during IPS (i.e., the frequencies ranging from 40–60 Hz that include the higher harmonics of the stimulus frequency). Both at rest and during IPS, the differences between the PS patients and controls were due primarily to clearly increased connectivity involving the anterior cortical regions. Significance: Our findings indicate that PS patients are characterised by abnormal EEG hyperconnectivity, primarily involving the anterior cortical regions under resting conditions and during IPS. This suggests that, even if the occipital cortical regions are the recipient zone of the stimulus and probably hyperexcitable, the anterior cortical areas are prominently involved in generating the hypersynchronization underlying the spike‐and wave discharges elicited by IPS.     

Epileptic seizures in relation to the age of SSPE onset]

The aim of this study is a clinical and electroencelographic analysis of those SSPE patients who suffered epileptic seizures in course of the disease. The material is based on an analysis of a computed database including 1180 case histories from multiple hospitalizations of 248 SSPE patients (141 males, 107 females) in years 1978-1995. The analysis was made using computer system EPI-INFO 6. The average age of SSPE onset was 12.3 +/- 4.5 (range 4-27.5). 74.2% of patients developed the disease before the age of 15. Epileptic seizures occurred in 43.5% (N = 108) of all SSPE patients in different stages of the disease. In 47 patients (M-21; F-26) they were observed among first SSPE symptoms, in 41 of those the seizures had the form of GTCS. Epileptic seizures were more frequent in patients with SSPE onset before the age of 15 (50.5%) than in patients with later onset (23.4%). More frequent occurrence of epileptic seizures and epileptiform changes in EEG in children under 15 can be associated with specificity of developmental age: immaturity of nervous and endocrine system and decreased convulsant threshold.     

Epileptic spasms preceded by partial seizures with a close temporal association

PURPOSE: To investigate the distinctive features of patients with West syndrome who had partial seizures followed by epileptic spasms (PS-ES). METHODS: We examined 45 patients with West syndrome whose epileptic spasms were recorded with simultaneous video-electroencephalography (EEG) monitoring between 1982 and 1996. We investigated the patients who had PS-ES and compared the PS-ES patients with the 37 patients without PS-ES. RESULTS: Of the 45 patients who had epileptic spasms in clusters (ES) and hypsarrhythmia on the interictal EEG, eight (17%) had ES preceded by partial seizures (PS) with a close temporal association. Seven of these eight were female patients. The underlying disorders were tuberous sclerosis (one patient), Aicardi syndrome (one), nonketotic hyperglycinemia (one), and focal cortical dysplasia (one). The etiology was unknown in the remaining four patients, but was suspected to be of prenatal origin in three. Three types of seizure sequence were identified: PS followed several seconds later by ES (two patients), alternating PS and ES starting with PS (three), and PS gradually replaced by ES with overlapping of the two (three). PS-ES disappeared or was replaced by other types of seizures in 1-34 months. Six patients could not walk, and all patients could not speak any sentences at age 3 years. CONCLUSIONS: Compared with patients without PS-ES, those with PS-ES more often had organic brain lesions of prenatal origin, other types of seizures before the onset of ES, asymmetric hypsarrhythmia on the EEG, and poor psychomotor outcome.     

Prospective Incidence Study and Clinical Characterization of Seizures in Newly Referred Adults

For 20 months, an extensive prospective search was made in a Swedish county to identify as many persons as possible aged greater than or equal to 17 years who had their first epileptic seizure or for the first time came to the attention of the medical community because of an epileptic seizure. The rate of initial diagnosis (first attendance rate) of non-provoked seizures was calculated as 34 in 100,000. For both sexes, the lowest age-specific incidences were found in persons aged 30-39 years. For males the highest age-specific incidence was found in the group aged 60-69 years and for females it was found in the group aged 50-59 years. The most common type of seizure was partial seizure, accounting for 60%. If seizures with rapid generalization and a known focal lesion are included, the number increases to 72%. A diagnostic delay greater than or equal to 1 year was found in 16%, mainly a patient delay. A cause for the epileptic seizure was found in 49%. A cerebrovascular disease was most common (21%). Brain tumors were found in 11% and trauma in 7%. A cause was more often identified in the older age groups. There was no significant difference between the sexes in the proportion of identified causes.     

Photoparoxysmal response on eye closure in photosensitive patients.

The Authors studied the presence of photoparoxysmal response (PPR) during intermittent photic stimulation (IPS) in 2,888 consecutive EEG recordings. PPR was present in 2.3% of EEGs and 10% of all patients referred to EEG laboratory for epilepsy (45 patients, 18 males, 27 females (M:F ratio 1:1.5), mean age 12 yrs). In 24 (53.3%) of these patients PPR was evident only (24.4%) or strikingly (28.9%) on eye closure during IPS. In 7 patients no other epileptic abnormalities were found on basal EEG and during hyperventilation, nor during IPS with eyes closed and with eyes open. The Authors consider the eye closure during IPS the most useful method to reveal a PPR in photosensitive patients and believe that a good IPS technique must include this procedure in the routine EEG examination.     

Diurnal and sleep/wake patterns of epileptic spasms in different age groups

Purpose: Epileptic spasms are seizures that occur predominantly in children and are characterized by clusters of brief axial movements. Epileptic spasms may occur in the context of a variety of syndromes. Previous research has found that epileptic spasms occur in a sleep/wake and diurnal rhythm. The purpose of this study was to identify these patterns in different age groups. Methods: Charts of 2,021 patients with epilepsy undergoing video–electroencephalography (EEG) monitoring over a 10‐year period were reviewed for presence of epileptic spasms and analyzed for their occurrence during the day (6 a.m. to 6 p.m.) or night, out of wake or sleep, and in 3‐h time‐blocks throughout the day. Exact epileptic spasm time, EEG localization, and the presence or absence of magnetic resonance imaging lesion were also recorded. Patients were separated into two age groups: A ages 3 and under, and over age 3. Statistical analysis of seizure occurrence in time bins was carried out using binomial calculations. p‐Values <0.05 were taken as significant. Using exact seizure times, a generalized linear mixed model of the Poisson‐family with a square root link function was used to calculate mean seizure times. Age, as a binary variable, and time, as a categorical variable, was treated as fixed effect predictors, and individual effects were modeled as random effects. For comparison between the two age groups, over age 3 and under age 3, seizure times were transformed into circular variables. A circular analysis of variance test was used to assess for the difference in mean seizure time, assuming a von Mises distribution of the circle. Key Findings: We analyzed 219 clusters of epileptic spasms in 51 patients (15 girls; mean age 2.15 ± 2.22 years). Forty‐two patients younger than 3 years of age had 163 seizures and nine patients older than 3 years had 56 seizures. Epileptic spasms occurred predominantly during wakefulness (p < 0.001) and during daytime (p < 0.001). Epileptic spasms occurred most frequently between 9 a.m. and noon (p < 0.05) and between 3 p.m. and 6 p.m. (p < 0.001). Patients without magnetic resonance imaging lesions had most seizures between 9 a.m. and noon (p < 0.01) and 3 p.m. and 6 p.m. (p < 0.001). Thirty‐seven patients had 157 epileptic spasms (71.2%) with generalized EEG patterns and 14 patients had 62 epileptic spasms (28.8%) with focal EEG patterns. Generalized EEG seizures occurred more frequently than focal EEG seizures (p < 0.001). Following age stratification, patients younger than 3 years had most epileptic spasms between 9 a.m. and noon (p < 0.05) and 3 p.m. and –6 p.m. (p < 0.01) and patients older than 3 years had most epileptic spasms between 6 a.m. and –9 a.m. (p < 0.05) and a second peak between 3 p.m. and 6 p.m., although the difference was not statistically significant due to insufficient numbers. Using continuous time analysis, the mean seizure time in the under age 3 and the over age 3 groups was 2:24 p.m. and 11:40 a.m. Using a circular analysis of variance test, the difference between mean seizure times in these groups was found to be statistically significant (p = 0.038). Significance: Epileptic spasms occur more frequently in the waking state and daytime. Younger patients have epileptic spasms mostly between 9 a.m. and noon and 3 p.m. and –6 p.m., and older patients have epileptic spasms mostly between 6 a.m. and 9 a.m. These findings emphasize age‐related changes in epileptic spasm pathophysiology or potentially evolution of disease with age.     

EEG sensitivity to television: effects of ambient lighting

The effect of ambient lighting on EEG sensitivity to television has been tested in 16 photosensitive epileptic patients. Those who were not sensitive to 50 Hz IPS responded to TV at a viewing distance of 1 m or less and showed a consistent increase of EEG activation by television when the room was brightly lit. Most of those who were sensitive to 50 Hz IPS were also TV-sensitive at viewing distances greater than 1 m and the effect was most marked with lights off. The results are discussed in the context of previous work showing that some patients with TV epilepsy respond to the raster pattern of the screen and some, at greater distance, to 50 Hz flicker.     

The effect of background illumination on sensitivity to intermittent photic stimulation

Sensitivity to intermittent photic stimulation (IPS) was tested in 23 photosensitive epileptic subjects under conditions of normal and reduced ambient lighting. Darkening the room to 20 lux did not increase either the incidence of photosensitivity or the effective range of flash frequencies. It is concluded that for routine clinical EEG examination there is no advantage in the current practice of darkening the room during IPS. For exhaustive testing of photosensitivity it is, however, necessary to perform IPS both in light and darkness.     

Epidemiology of Guillain-Barré syndrome

From 1969 through 1972, a nationwide search for cases of Guillain-Barré syndrome (GBS) is Israel revealed 89 patients. The average annual age-adjusted incidence was 0.75 per 10(5) persons. Overall incidence of the syndrome was similar in Jewish groups of diverse ethnic backgrounds. Arabs had a lower overall incidence than Jews (0.46 per 10(5) persons), perhaps attributable to fewer Arabs at risk in older age groups. Peaks of incidence occurred among individuals over 60 and under 4 years of age when all cases were combined. No clear seasonal or geographic clustering of GBS was evident in Israel during the 4 years of this study. The incidence of GBS in the present study agrees with previous population-based estimates.     

Evidence That Emotional Maladjustment Is Worse in Men Than in Women with Psychogenic Nonepileptic Seizures

The purpose of this study is to examine the effects of gender on adjustment and cognition in patients with psychogenic nonepileptic seizures (NES) and on patients with epilepsy. We compared 57 women and 27 men, all at least 16 years old, with only NES as documented by long-term EEG-video monitor studies, to equal numbers of randomly selected women and men with only epileptic seizures. Variables examined included age, age of onset, education, scales from the MMPI, the WAIS-R, and the number of tests outside normal limits from the Neuropsychological Battery for Epilepsy. We found no significant differences in mean age, intelligence, or percentage of neuropsychological tests outside normal limits across the four groups. Women and men with NES had significantly later age of onset of attacks compared with subjects of either gender with epilepsy (26 years vs 13 years, P < 0.001) and men with NES had greater educational achievement than women with NES or patients with epilepsy (P < 0.02). However, the most important findings were seen on the MMPI. Men with NES exhibited significantly greater elevations on multiple scales (especially Hysteria, Depression, Hypochondriasis, Psychoasthenia, Schizophrenia) compared with men with epilepsy or women with either epilepsy or NES. We conclude that men with NES have significantly worse patterns of emotional adjustment, as measured by the MMPI, than women with NES or subjects of either gender with epilepsy.     

Late outcome of very severe blunt head trauma: a 10-15 year second follow-up.

Forty patients with very severe blunt head trauma (post-traumatic amnesia greater than or equal to 1 month) were initially examined at an average of 4.5 months after the injury. The patients were visited in their homes 2.5 years and 10-15 years after the accident and questionnaires were presented to patients, relatives and/or staff. Though physical impairment, dysarthria and defects of memory remained severe in many cases, the psychosocial sequelae presented the most serious problems. Permanent changes in personality and emotion were reported in two thirds and were especially frequent among the youngest patients. The worse overall outcome was seen in cases with severe brainstem involvement or anterior lesions or both. In spite of the great frequency of deficits long-term improvement of functional state was common and several regained at least some work capacity.     

Depressive disorders among epileptic patients attending a specialised outpatient clinic

The overall prevalence of psychiatric disorders in epileptic patients is estimated between 19 and 62%. Depressive disorders may be the most common psychiatric disorders and the main reason for psychiatric hospitalisation and taking psychotropic drugs. The underdiagnosis and undertreatment of depressive disorders among epileptic patients represent a problem of considerable magnitude. The aim of the present study was to evaluate the prevalence of depressive disorders among patients with primary epilepsy and to determine the risk factors of the occurrence of the depressive illness. The survey was conducted in a outpatient epilepsy clinic in the Ibn Rochd University Hospital Centre in Casablanca. All patients with idiopathic or cryptogenic epilepsy aged 15 Years and above, were eligible, except for patients with severe physical and mental disabilities. Neurologists diagnosed the epilepsy based on clinical criteria with electroencephalograms data. The depressive disorders met a psychiatrist's evaluation of an ICD-10 criterion. Ninety-two subjects participated in the survey, 57.6% were men and the mean age was 30.3 +/- 10.8 Years. The epilepsy age of onset was 16.3 +/- 11.4 Years with an average duration of 14.1 +/- 9.2 Years. The prevalence of depressive disorders among epileptic patients in our survey was 18.5%. According to sex, the prevalence was 23.1% in women and 15.1% in men. The depressed patients were compared with the remaining patients without depression with regard to seizure variables and sociodemographic characteristics. The epilepsy-depression and epilepsy-control groups did not differ significantly in the duration of epilepsy or in the type of anticonvulsant therapy (mono versus polytherapy). Three variables were significantly different between the two groups. The mean age in the epilepsy-depression group was significantly higher (34.4 +/- 9.6 Years versus 29.4 +/- 10.9, p<0.03), the mean age of epilepsy age of onset was also higher in the epilepsy-depression group than in the epilepsy-control group (21.8 +/- 11.9 Years versus 15.04 +/- 11.0, p<0.03) and the seizure frequency per week was more important among depressed epileptic patients (2.4 + 5.2 seizures versus 0.4 + 1.5, p<0.007). The present survey confirms the findings of previous studies that the prevalence of the comorbidity between epilepsy and depression is common in specialised outpatient units. The detection and the treatment of depressive disorders among the epileptic patients remains a very great challenge in the management of the epileptic illness. It will improve the quality of life of these patients. A closer involvement of psychiatric and psychological treatment in patient management is necessary.     

Sydenham's chorea and seizures. Clinical and electroencephalographic studies

The hospital records of 28 children (mean age, 9.4 years) with typical Sydenham's chorea were reviewed. Nineteen of 28 patients had antistreptolysin O titers of greater than or equal to 200 Todd units. Other causes of chorea were excluded by appropriate laboratory and clinical follow-up studies. At the onset of the movement disorder, 17 of 28 patients had abnormal EEGs consisting of irregular posterior slowing in 15, sharp epileptic spikes in 5, and high-voltage sharp waves in 2. Two patients with spikes predominantly in the temporal lobe regions developed complex partial seizures. On follow-up evaluation, the EEGs returned to normal within one to four weeks. Seizures did not recur after therapy with anticonvulsants. Seizures have been reported only rarely in association with Sydenham's chorea. Our observation suggests that seizures may occur during chorea but may often be masked by frequent choreic movements and thus not recognized. The EEG changes and seizures were transient in our patients studied so far.     

Eye closure related spike and wave discharges: clinical and syndromic associations.

Precipitation of spike and wave (SW) discharges in some epileptic patients by eye closure (EC) has rarely been reported. To disclose the clinical characteristics and classification of syndromes of epileptic patients with SW discharges induced by EC, we investigated 10 patients (1 M, 9 F) showing this peculiar EEG feature. The patients aged between 9-39 years (mean 20.6 +/- 9.058), underwent short-term (1-3.5 hr) video-EEG investigations in order to document the appearance of the SW discharges within 3 seconds of the act of EC, in at least two occasions. Clinical analysis showed that 5 female patients who had the syndrome of juvenile myoclonic epilepsy (JME) had a later onset of epilepsy (13-15 years) than the 3 patients (3 girls) with eyelid myoclonia with absences (EMA) (3-8 years of age at onset). The remaining 2 patients who were diagnosed as childhood absence epilepsy (CAE) and juvenile absence epilepsy (JAE) according to the international classification, did not show photosensitivity on the video-EEG. All but one of the 5 JME patients had experienced myoclonic seizures in intermittent photic stimulation (IPS) at the time of EC, associated with multiple spike and wave discharges. Two of the 3 EMA patients exhibited typical absences with eyelid myoclonia during the act of EC. The high rate of family history of epilepsy in first degree relatives of our patients was an outstanding feature, which could have future implications in research of the genetic basis of epilepsy patients with ECS.     

Partial epilepsy associated to primary brain tumors

OBJECTIVE: To characterize the epileptic syndrome of patients with primary cerebral tumor of slow growth. METHOD: Clinical evaluation of fourty two patients with refractory epilepsy associated with cerebral tumor of slow growth were operated between June 1992 and September 1999. RESULTS: Almost 75% of the patients were less than 15 years old when they began the epileptic crises, 67.7% had normal neurological exam in the first evaluation. More than 90% of the total had seizures of the partial complex type, frequently inferior to 16 per month. The seizures were partial simple (PS) developing for partial complex (PC) in 10 patient and only PC in 11 Partial complex associated with generalized tonic-clonic seizure (GTC) happened in 11 patients, PS for PC and GTC in 4 patients. CONCLUSION: The crises of the partial type, with not very high frequency, can suggest a precocious manifestation of the tumor in the children, even with normal neurological exam.     

Epileptic seizures,cranial neuralgias and paroxysmal symptoms in remitting and progressive multiple sclerosis

The occurrence of a first epileptic seizure, spinal or brainstem paroxysmal symptom and cranial neuralgia during 25 years after onset was studied in a population-based multiple sclerosis (MS) cohort of 255 patients. Epileptic seizures occurred in 20, paroxysmal symptoms in 11 and cranial (trigeminal, intermedius, retroauricular or occipital) neuralgia in 11 patients. The yearly incidence of epileptic seizures in MS was estimated to be 349(+/-153)/100,000, approximately seven times higher than in the general population. The yearly incidence of a first paroxysmal symptom in the present material was calculated to be 190 cases in 100,000 MS patients, and the yearly incidence of cranial neuralgia was 189 cases in 100,000 MS patients. The epileptic seizures were more frequent during the progressive course than in the relapsing-remitting (RR) course. The frequencies of paroxysmal symptoms and cranial neuralgia did not differ between these two disease courses. A coincidence of epileptic seizures and a decline in cognitive functioning not seen among patients with paroxysmal symptoms was found The relatively late occurrence of epileptic seizures indicates that the frequency of epileptogenesis, known to involve neuronal damage, increases in the later stages of MS.     

Differentiating early clinical features of Panayiotopoulos syndrome from acute encephalopathy

BackgroundPanayiotopoulos syndrome (PS) is a common benign epilepsy in childhood, characterized by predominantly autonomic symptoms such as emesis, pallor, and seizures, which are often prolonged. In an emergency room (ER), particularly when unconsciousness is prolonged, differentiating PS from acute encephalopathy is challenging. In this study, we aimed to elucidate the differences in clinical features of patients with PS and acute encephalopathy who visited our ER.MethodsWe retrospectively reviewed 18 patients who were transferred to our ER because of status epilepticus later diagnosed as PS, and 30 patients with acute encephalopathy, between July 2012 and July 2017. We compared patient demographics, clinical characteristics, and treatment.ResultsMost patients (90%) with acute encephalopathy had convulsive seizures of greater than or equal to 15 min, whereas only three patients (17%) with PS had convulsive seizures of greater than or equal to 15 min (P < 0.001). In addition, seizures were treatable in all patients with PS with a small dose of midazolam (0.1 mg/kg), but all patients with acute encephalopathy required midazolam at 0.3 mg/kg or more (P < 0.001). More patients with PS had autonomic symptoms compared to those with acute encephalopathy (e.g., vomiting [78% vs. 3%, P < 0.001]). Non-convulsive status epilepticus was observed in 22% of PS patients, but not in any acute encephalopathy patients. In contrast, fever was observed in all patients with acute encephalopathy (100%), but less frequently in those with PS (11%, P < 0.001).ConclusionPS was characterized by 1) convulsive seizures shorter than 15 min, 2) seizures treatable with small doses of midazolam, and 3) autonomic symptoms. PS could be differentiated from acute encephalopathy in the early stages of the syndrome.     

Abnormal functional connectivity in Alzheimer’s disease: intrahemispheric EEG coherence during rest and photic stimulation

Electroencephalography (EEG) coherence provides a measure of functional correlations between two EEG signals. The present study was conducted to examine intrahemispheric EEG coherence at rest and during photic stimulation (PS; 5, 10 and 15 Hz) in ten unmedicated patients with presenile dementia of the Alzheimer type (AD; mean age at onset 56 years). In the resting EEG, the AD patients had significantly lower coherence than gender- and age-matched control subjects in the alpha-1, alpha-2 and beta-1 frequency bands. The EEG analysis during PS also showed that the patients had significantly lower coherence in the frequency corresponding to PS at 10 and 15 Hz. In this study, the changes in coherence from the resting state to the stimulus condition (i.e. PS-related coherence reactivity) were examined. The patients were found to show significantly smaller coherence reactivity to PS at 5 and 15 Hz. These findings suggest that, in addition to the resting state, AD patients have an impairment of intrahemispheric functional connectivity during PS. They also suggest that AD shows a failure of PS-related functional reorganization. Received: 5 August 1997 / Accepted: 18 June 1998     

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.