Takushi Inoue

Okayama University, Okayama, Okayama, Japan

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Publications (17)48.5 Total impact

  • Clinical Neurophysiology 06/2015; 126(6). DOI:10.1016/j.clinph.2015.02.015 · 2.98 Impact Factor
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    ABSTRACT: Purpose: Ictal fear is an uncommon condition in which fear manifests as the main feature of epileptic seizures. The literature has suggested that ictal fear is generally associated with poor seizure outcomes. We wanted to clarify the variability in seizure outcome of children with ictal fear. Subjects and methods: We identified five pediatric patients with ictal fear who were followed up on at Okayama University Hospital between January 2003 and December 2012. We retrospectively reviewed their clinical records and EEG findings. Results: The onset age of epilepsy ranged from 8 months to 9 years and 10 months. The common ictal symptoms were sudden fright, clinging to someone nearby, and subsequent impairment of consciousness, which were often accompanied by complex visual hallucinations and psychosis-like complaints. Ictal fear, in four patients, was perceived as a nonepileptic disorder by their parents. Ictal electroencephalograms (EEG) of ictal fear were obtained in all patients. Three showed frontal onset, while the other two showed centrotemporal or occipital onsets. Two patients were seizure free at last follow-up, while seizures persisted in the other three. A patient with seizure onset during infancy had a favorable outcome, which was considered to be compatible with benign partial epilepsy with affective symptoms. Conclusion: Ictal fear is not always associated with a symptomatic cause or a poor seizure outcome. It is quite important to make a correct diagnosis of ictal fear as early as possible to optimize treatment.
    Brain & development 10/2014; 36(9). DOI:10.1016/j.braindev.2013.11.011 · 1.54 Impact Factor
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    ABSTRACT: We explored high-frequency activity in the suppression-burst (SB) pattern of interictal electroencephalogram (EEG) in early infantile epileptic encephalopathy including Ohtahara syndrome (OS) and early myoclonic encephalopathy (EME) to investigate the pathophysiological characteristics of SB. Subjects included six patients with the SB EEG pattern related to OS or EME (Group SB). The results were evaluated in comparison to tracé alternant (TA) observed during the neonatal period in nine patients to rule out possible nonspecific relationships between high-frequency activity and periodic EEG patterns (Group TA). EEG was digitally recorded with a sampling rate of 500Hz and the analysis was performed in each of the particular bipolar channel-pairs. We visually selected 20 typical consecutive burst sections and 160 inter-burst sections for comparison from the sleep record of each patient and performed the time-frequency analysis. We investigated the maximum frequencies of power enhancement in each derivation in both groups. In Group SB, a significant increase in power at a frequency of 80-150Hz was observed in association with the bursts, particularly in the bilateral parieto-occipital derivations, in all patients. In Group TA, on the contrary, no significant increase in high-frequency power was found. The maximum frequencies of power enhancement were significantly higher in Group SB than in Group TA (p<0.001 by repeated-measures ANOVA). Interictal high frequencies of up to 150Hz were detected in the suppression-burst EEG patterns in epileptic encephalopathy in early infancy. Further studies will be necessary to identify the role of the interictal high-frequency activity in the pathophysiology of such early epileptic encephalopathy.
    Brain & development 05/2014; 37(2). DOI:10.1016/j.braindev.2014.04.004 · 1.54 Impact Factor
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    ABSTRACT: Purpose: Benign childhood epilepsy with centro-temporal spikes (BECTS) and Panayiotopoulos syndrome (PS) have different pathophysiologies and show different types of seizures, yet they overlap in some important respects. In an attempt to understand the ways in which they differ from each other and overlap each other, we performed a detailed investigation on patients who had both characteristic types of seizure manifestations, namely, sylvian seizures and emetic seizures. Subjects and methods: We recruited consecutive subjects from the EEG database of outpatients who had visited our hospital between 2008 and 2010 and who had been diagnosed with BECTS or PS. As a result, 45 patients with BECTS and 50 patients with PS were selected from the database. Viewing the clinical records of these 95 patients, five patients were selected who had experienced both sylvian seizures and emetic seizures. Next, the clinical features and EEG findings of these five patients were retrospectively observed at the date of investigation: October 1, 2011. Results: We found that all the patients showed rolandic spikes when they had sylvian seizures, and occipital spikes or multifocal spikes when they had emetic seizures. We also report in detail on one patient who showed two different types of ictal EEG patterns: one of which started in the occipital area and the other of which was located in the rolandic area. Conclusion: Based on these findings, we conclude that widespread cortical hyperexcitability that includes the occipital area is necessary to produce the autonomic seizure manifestations seen in PS.
    Brain & development 01/2014; 37(1). DOI:10.1016/j.braindev.2014.01.013 · 1.54 Impact Factor
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    ABSTRACT: The aim of this study was to assess the anticonvulsant effect of carbon dioxide (CO(2)) on Scn1a mutation-related febrile seizures. We examined physiological changes in the blood gas levels after the induction of hyperthermia-induced seizures (HISs), which were associated with the Scn1a missense mutation. We determined the efficacy of inhalation of 5% or 10% CO(2) to treat HISs. HISs were evoked in Scn1a mutant and wild-type (WT) rats by hot water baths. To determine the anticonvulsant effect of CO(2) inhalation, rats were placed in a chamber filled with air or mixed gas containing 5% CO(2) or 10% CO(2) for 3min, immediately after the induction of HISs. We also analyzed the blood gas levels at the end of inhalation of CO(2). Hot water bathing induced a significant reduction in the partial pressure of CO(2) (pCO(2)) and respiratory alkalosis in the WT and Scn1a mutant rats. HISs were evoked in 100% of the Scn1a mutant rats within 5min, but in none of the WT rats. The Scn1a mutant rats demonstrated a higher HISs susceptibility associated with respiratory alkalosis than the WT rats. Inhalation of 10% CO(2) shortened the seizure duration from 62.6±12.1s to 15.5±1.0s. Blood gas analysis after the inhalation of 10% CO(2) demonstrated an elevated pCO(2) level and respiratory acidosis. Inhalation of 10% CO(2) demonstrated a potent and fast-acting anticonvulsant effect against HISs.
    Epilepsy research 01/2013; 105(1-2). DOI:10.1016/j.eplepsyres.2013.01.003 · 2.19 Impact Factor
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    ABSTRACT: High-frequency oscillations (HFOs) associated with continuous spike-waves during slow-wave sleep (CSWS) are speculated to be linked to the disturbance of higher brain function. We intended to investigate the generative mechanisms of HFOs in CSWS by clarifying the effects of intravenous injection (IV) of diazepam (DZP), an agonist for the gamma-aminobutyric acid A (GABA(A)) receptor in the GABAergic interneuron system, in patients who had previously been treated with IV DZP. The subjects were three patients with epilepsy with CSWS. For each patient, EEG data before and after IV DZP were separated into consecutive 5-min sections. Time-frequency power spectral analysis was performed on the spikes of each section, and peak-power and frequency of detected high-frequency spectral spots were compared before and after IV DZP. Spectral spots with peak-frequencies at 85.9-121.1Hz in the ripple band were revealed in all three patients. Although the amplitudes of the spikes largely returned to the baseline levels 20-25min after IV DZP, the recovery of the peak-power levels of HFOs lagged behind that of the spike amplitudes, and the power levels of HFOs were lower than the baseline data within 25min after the injection of DZP. No consistent changes were found regarding the spectral frequencies of HFOs. The dissociation of the effect of IV DZP in terms of recovery when comparing spike-amplitudes and the power of HFOs may correspond to an already suggested difference in the pathophysiological mechanisms that generate the spikes and HFOs.
    Brain & development 10/2012; 35(6). DOI:10.1016/j.braindev.2012.09.002 · 1.54 Impact Factor
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    ABSTRACT: We examined high-frequency oscillations (HFOs) in the ictal cortical EEGs of hyperthermia-induced seizures in a rat model of febrile seizures with an SCN1A mutation as a means of investigating the pathophysiological mechanisms underlying the generation of febrile seizures. We used 13 male homozygous Scn1a-N1417H mutant rats (F344/NSlc-Scn1a(Kyo811)) and 10 wild-type control rats. Generalized tonic-clonic seizures were induced in all mutant rats, and HFOs with frequencies ranging from 200 to 400Hz were found to precede spikes during the clonic phases of these seizures in the ictal EEGs. The proportion of all spikes in each seizure that were associated with HFOs increased with age. In time-frequency spectra of the EEG data, the HFOs had a mean peak frequency of 301.1±65.4Hz (range: 156.3-468.8Hz) and a mean peak power of 24.6±3.8dB (range: 11.4-33.4dB); the peak power increased with age. Regarding the wild-type rats, a brief seizure without unmistakable HFOs was exceptionally induced in only one rat. The generation mechanism of febrile seizures is still an unanswered question. The detection of HFOs from the ictal EEGs of hyperthermia-induced seizures may provide a cue to answering this open question, although in this research we were unable to provide sufficient evidence to prove that the generation of HFOs depended on the mutation.
    Epilepsy research 08/2012; 103(2-3). DOI:10.1016/j.eplepsyres.2012.07.020 · 2.19 Impact Factor
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    ABSTRACT: To improve the interpretability of figures containing an amplitude-integrated electroencephalogram (aEEG), we devised a color scale that allows us to incorporate spectral edge frequency (SEF) information into aEEG figures. Preliminary clinical assessment of this novel technique, which we call aEEG/SEF, was performed using neonatal and early infantile seizure data. We created aEEG, color density spectral array (DSA), and aEEG/SEF figures for focal seizures recorded in seven infants. Each seizure was paired with an interictal period from the same patient. After receiving instructions on how to interpret the figures, eight test reviewers examined each of the 72 figures displaying compressed data in aEEG, DSA, or aEEG/SEF form (12 seizures and 12 corresponding interictal periods) and attempted to identify each as a seizure or otherwise. They were not provided with any information regarding the original record. The median number of correctly identified seizures, out of a total of 12, was 7 (58.3%) for aEEG figures, 8 (66.7%) for DSA figures and 10 (83.3%) for aEEG/SEF figures; the differences among these are statistically significant (p=0.011). All reviewers concluded that aEEG/SEF figures were the easiest to interpret. The aEEG/SEF data presentation technique is a valid option in aEEG recordings of seizures.
    Epilepsy research 07/2011; 96(3):276-82. DOI:10.1016/j.eplepsyres.2011.06.012 · 2.19 Impact Factor
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    ABSTRACT: We explored high-frequency oscillations (HFOs) in scalp sleep electroencephalography (EEG) studies of patients with idiopathic partial epilepsy (IPE) of childhood in order to obtain a better understanding of the pathologic mechanisms underlying IPE. The subjects were 45 patients, including 32 with benign childhood epilepsy with centrotemporal spikes (BCECTS) and 13 with Panayiotopoulos syndrome (PS). A total of 136 EEG records were investigated through temporal expansion and filtering of traces and time-frequency spectral analysis. HFOs with frequency of 93.8-152.3 Hz (mean 126.2 ± 13.6 Hz) in the band of ripples were detected in association with spikes in 97 records (71.3%). Time from last seizure to the EEG recording was significantly shorter in those with spike-related HFOs than in the EEG recordings with spikes without HFOs (p = 0.006). Although time from last seizure reflects age, age at the time of recording was not significantly different between EEG studies with and without HFOs. Peak-power values of the high-frequency spots in time-frequency spectra were significantly negatively correlated with time from last seizure (R(2) = 0.122, p < 0.001) but not with age at the time of recording. Peak frequencies of the high-frequency spectral spots were not significantly correlated with age at the time of recording or with time from last seizure. The close relationship between the generation of spike-related HFOs and the period of active seizure occurrence indicated that HFOs may tell us more about epileptogenicity in IPE than the spikes themselves. Because there is a spectrum of pediatric epileptic disorders extending from the benign end of BCECTS to the encephalopathic end of epilepsy with continuous spike-waves during slow-wave sleep (CSWS), and HFOs that have already been detected in association with CSWS were more prominent than HFOs in IPE, intense spike-related HFOs may indicate poor prognosis.
    Epilepsia 07/2011; 52(10):1812-9. DOI:10.1111/j.1528-1167.2011.03169.x · 4.58 Impact Factor
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    ABSTRACT: Because high-frequency oscillations (HFOs) may affect normal brain functions, we examined them using electroencephalography (EEG) in epilepsy with continuous spike-waves during slow-wave sleep (CSWS), a condition that can cause neuropsychological regression. In 10 children between 6 and 9 years of age with epilepsy with CSWS or related disorders, we investigated HFOs in scalp EEG spikes during slow-wave sleep through temporal expansion of the EEG traces with a low-cut frequency filter at 70 Hz as well as through time-frequency power spectral analysis. HFOs (ripples) concurrent with spikes were detected in the temporally expanded traces, and the frequency of the high-frequency peak with the greatest power in each patient's spectra ranged from 97.7 to 140.6 Hz. This is the first report on the detection of HFOs from scalp EEG recordings in epileptic patients. We speculate that epileptic HFOs may interfere with higher brain functions in epilepsy with CSWS.
    Epilepsia 04/2010; 51(10):2190-4. DOI:10.1111/j.1528-1167.2010.02565.x · 4.58 Impact Factor
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    ABSTRACT: EEG gamma rhythms, which are found in association with epileptic spasms in infants with West syndrome, were explored in the ictal EEGs of tonic seizures in older patients with Lennox-Gastaut syndrome (LGS) to investigate the pathophysiology of the disease. The subjects were 20 patients with LGS (11 males, 9 females; age range: 3 years 1 month to 29 years 3 months) who had at least one digitally recorded tonic seizure with minimal artifacts. A time-frequency analysis was applied to each patient's ictal EEG data. A total of 54 seizures were analyzed, excluding spasms in clusters. The ictal EEGs of the tonic seizures showed only diffuse desynchronization in 10 seizures, and desynchronization followed by rhythmic activity in 21. The ictal discharges started as rhythmic activity of varying amplitude without initial desynchronization in 23 seizures. In a total of 25 seizures from 13 patients, gamma rhythms with frequencies ranging from 43 to 101.6Hz were detected by temporal expansion of the ictal EEG traces and spectral analysis. In 24 (96%) of these seizures, gamma rhythms were observed at seizure onset corresponding to visually identified desynchronization. In the remaining seizure, gamma rhythms were found in association with transient suppression of high-amplitude rapid discharges. The detection of gamma rhythms in the ictal EEGs of tonic seizures indicated that some tonic seizures might have generative mechanisms in common with epileptic spasms, and that these mechanisms are possibly related to desynchronization at seizure onset.
    Epilepsy research 05/2009; 86(1):15-22. DOI:10.1016/j.eplepsyres.2009.03.011 · 2.19 Impact Factor
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    ABSTRACT: To elucidate the pathophysiology of epileptic spasms, unaveraged time-frequency spectra of spasm-associated EEG gamma rhythms were investigated in 15 patients with West syndrome or related disorders. Using these unaveraged spectra, we were able to investigate in detail various aspects of the structure of ictal gamma rhythms that could not be examined using averaged spectra. The characteristics of the ictal gamma peaks (peak frequency, power, duration, and the number of peaks in each brain-region for each spasm) were statistically evaluated with respect to their differences among the brain regions and over the time-course of the clusters. Our findings were as follows: (1) Gamma peaks were clearly detected in most spectra and generally had a similar pattern in each spasm, which repeated in clusters. (2) The mean frequency of gamma peaks was 69.2+/-16.8Hz, and the number of peaks in each brain region of each spasm was 1.83+/-1.16. (3) The occipitoparietal gamma peaks had significantly greater power and longer duration than the frontocentral peaks. (4) The frequency of the gamma peaks was higher in the mid phase of clusters than in the ending, and it tended to have a positive correlation with its latency from the preceding beta peak. An analysis of the ictal gamma rhythms might give some insight into the generative mechanism of spasms.
    Brain and Development 06/2008; 30(5):321-8. DOI:10.1016/j.braindev.2007.10.003 · 1.54 Impact Factor
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    ABSTRACT: Mutations in the SCN 1 A gene, encoding the neuronal voltage-gated sodium channel alpha1 subunit, cause SMEI, GEFS+, and related epileptic syndromes. We herein report the R1575C-SCN 1 A mutation identified in a patient with Rasmussen encephalitis. R1575C were constructed in a recombinant human SCN 1 A and then heterologously expressed in HEK293 cells along with the human beta1 and beta2 sodium channel accessory subunits. Whole-cell patch-clamp recording was used to define biophysical properties. The R1575C channels exhibited increased channel availability and an increased persistent sodium current in comparison to the wild-type. These defects of electrophysiological properties can result in neuronal hyperexitability. The seizure susceptibility allele may influence the pathogenesis of Rasmussen encephalitis in this case.
    Epilepsia 04/2008; 49(3):521-6. DOI:10.1111/j.1528-1167.2007.01411.x · 4.58 Impact Factor
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    ABSTRACT: As a part of the study to prevent West syndrome (WS) by early treatment, we assessed what kind of epilepsy developed in infants who showed epileptic discharges in early infancy. EEG examinations were performed on 116 infants born from 1997 to September 2004, both before and after 3 months of corrected age (CA). We divided 45 infants who showed epileptic discharges in early infancy into two groups according to the existence of periventricular leukomalacia (PVL) and retrospectively performed the course observation at the survey point on April 1 in 2005. Out of 45 infants showing epileptic discharges in early infancy, 26 developed WS. Compared with infants without PVL, infants with PVL were more likely to develop WS than infants without PVL. Furthermore, infants with PVL were more likely to develop WS than other types of epilepsy. Namely, 11 out of 17 infants with PVL developed WS at the survey point. All infants with WS showed initial epileptic discharges before 5 months of corrected age (CA), and most of them (except for five) had initial epileptic discharges before 3 months of CA. There were two infants who once developed hypsarrhythmia on EEG; however, after starting VPA therapy, they did not develop WS with the improvement of EEG findings, and one was presented here in detail. We proposed that preterm infants with PVL who showed epileptic discharges before 3 months of CA should be treated by antiepileptic drugs to prevent the onset of WS syndrome.
    Brain and Development 06/2007; 29(4):217-23. DOI:10.1016/j.braindev.2006.08.010 · 1.54 Impact Factor
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    ABSTRACT: Panayiotopoulos syndrome (PS) is a type of benign childhood partial epilepsy that is frequently associated with abundant multifocal spikes other than main occipital spikes on the EEG. In this study, we investigated the characteristic features of dipoles in PS. We performed dipole analysis of the interictal occipital spike discharges seen in 10 children with PS (group A) and in 10 children with other types of symptomatic localization-related epilepsy (group B). We analyzed the dipoles of the averaged spike in each patient. In group A, the averaged occipital spikes in each patient showed dense dipole locations in the mesial occipital area; in group B, widely scattered dipole locations were observed. In Group A, the geometric centers of the dipoles at each time point (such as at the main negative peak and before or after the main peak) were estimated in the neighboring locations. In contrast, they tended to be scattered in group B. Our study reveals that PS has high dipole stability, similar to that of rolandic epilepsy. From the electroencephalographic view, this seems to indicate a close link between these two syndromes.
    Epilepsia 05/2006; 47(4):781-7. DOI:10.1111/j.1528-1167.2006.00519.x · 4.58 Impact Factor
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    ABSTRACT: The high-voltage slow waves (HVSs) on EEG associated with epileptic spasms were investigated to clarify their characteristics and their relation to the pathophysiology of spasms in West syndrome and related disorders. In 14 patients, digitally recorded EEG segments showing the ictal HVSs were extracted and their traces were overlaid by using an average reference. The ictal HVSs were also averaged to build maps for investigation of the pattern of potential distribution over the scalp. In a total of 685 recorded spasms, 346 (50.5%) with minimal artifacts were selected to demonstrate that the ictal HVSs had a largely consistent waveform and distribution in each patient. The ictal HVSs were symmetrical in 10 patients and asymmetrical in the other four, and were relatively negative over the posterior region and positive over the frontal or temporal regions in 11 patients. Two symptomatic patients showed a marked deviation of the distribution of HVSs to the pathologically more involved hemisphere. An infant with Aicardi syndrome had two different types of spasms, each type showing a consistent pattern of HVSs with a lateralized distribution. The patterns of distribution of the ictal HVS may be related to the abnormal activation of the brain in the generation of spasms.
    Epilepsia 08/2005; 46(7):1098-105. DOI:10.1111/j.1528-1167.2005.63004.x · 4.58 Impact Factor
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    ABSTRACT: Very fast activity was investigated on the ictal EEGs of epileptic spasms to elucidate the pathophysiology of West syndrome (WS) and related disorders from a novel point of view. The traces of scalp ictal EEG of spasms temporally were expanded in 11 patients whose clinical diagnosis was symptomatic WS in six, cryptogenic WS in two, Aicardi syndrome in one, and symptomatic generalized epilepsy after WS in the remaining two. Time evolution of averaged power spectra of the ictal fast activity also was analyzed in each patient. Rhythmic gamma activity with frequency ranging from 50 to 100 Hz was detected in a total of 345 of 537 spasms. Fast activity was seen bilaterally in nine patients, was lateralized to one hemisphere in another, and appeared independently on each hemisphere in the remaining infant with Aicardi syndrome. Power spectra showed a clear peak corresponding to spasm-associated gamma rhythm, with frequency centering approximately 65 Hz and ranging from 51 to 98 Hz. The morphology and spectral characteristics of ictal gamma rhythm were completely different from those of muscle activity or alternating current (AC) artifacts. Spasm-associated gamma activity was clearly detected on the scalp. This observation may provide a clue to the pathophysiology of spasms.
    Epilepsia 06/2004; 45(5):488-96. DOI:10.1111/j.0013-9580.2004.45703.x · 4.58 Impact Factor