研究者詳細 - 秋山　倫之

Epileptic spasmsの発作時脳波における極高周波律動のシリーズ中の一定性に関する研究

井上拓志, 小林勝弘, 岡牧郎, 秋山倫之, 中堀智之, 大塚頌子

臨床神経生理学 32 ( 5 ) 599 - 599 2004年10月

Very fast rhythmic activity on scalp EEG associated with epileptic spasms 査読

K Kobayashi, M Oka, T Akiyama, T Inoue, K Abiru, T Ogino, H Yoshinaga, Y Ohtsuka, E Oka

EPILEPSIA 45 ( 5 ) 488 - 496 2004年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：BLACKWELL PUBLISHING INC

Purpose: 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.
Methods: 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.
Results: 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 similar to65 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.
Conclusions: Spasm-associated gamma activity was clearly detected on the scalp. This observation may provide a clue to the pathophysiology of spasms.

DOI： 10.1111/j.0013-9580.2004.45703.x

A study of spike-density on EEG in West syndrome 査読

M Oka, K Kobayashi, T Akiyama, T Ogino, E Oka

BRAIN & DEVELOPMENT 26 ( 2 ) 105 - 112 2004年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

To elucidate the pathophysiology of spasms in series, the distribution and density of spikes on hypsarrhythmia were studied in 13 patients with West syndrome by excluding slow waves from EEG using a digital filter. (1) Interictal spikes were mostly multifocal and dominant over the bilateral posterior head area with very few diffuse discharges. Therefore, spikes on hypsarrhythmia were demonstrated to occur actually depending on the brain regions although they appeared random. (2) The dominant region of interictal spikes did not correspond to the underlying focal cortical lesion in many patients, and was indicated to reflect the general process of cerebral maturation in infancy. (3) There were far fewer inter-spasm spikes, especially during the middle phase of a series of spasms, than interictal spikes. It was implied that the cortical activity of hypsarrhythmia was interfered with by the abnormal subcortical function, which might be related to the generation of spasms. (4) The dominant region of inter-spasm spikes tended to coincide with a focal cortical lesion shown by MRI and the focus of associated partial seizures. (C) 2003 Elsevier B.V. All rights reserved.

DOI： 10.1016/S0387-7604(03)00101-3

Initiation of treatment and selection of antiepileptic drugs in childhood epilepsy 査読

E Oka, T Murakami, T Ogino, T Kobayashi, Ohmori, I, T Akiyama, M Ito

EPILEPSIA 45 17 - 19 2004年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：WILEY-BLACKWELL

Purpose: A retrospective study was carried out on 53 cases with childhood epilepsy to evaluate the validity of the initial selection of antiepileptic drug (AED).
Methods: We investigated the AEDs selected at the beginning of the treatment from the medical records of 53 untreated cases. A follow-up study was undertaken to evaluate the effects of the AEDs. In the second study, we investigated the AEDs of 10 cases with atypical benign partial epilepsy (ABPE), to clarify whether the initial AEDs selected for rolandic epilepsy were related to the appearance of ABPE.
Results: The AEDs used at the initial stage consisted of carbamazepine (CBZ), valproic acid (VPA), phenobarbital (PB), and vitamin B-6. The main AEDs were CBZ and VPA for localization-related epilepsy, and VPA for generalized epilepsy. The initial selection of AEDs in 41 (85.4%) of 48 cases treated with AEDs were considered to be correct from the results of follow-up. We could not specify any AEDs that related to the appearance of ABPE.
Conclusions: The selection of AED in this series was considered to be most appropriate. We proposed a criterion to determine whether to begin the AED treatment immediately at the initial seizure.

DOI： 10.1111/j.0013-9580.2004.458004.x

Panayiotopoulos症候群のdipole分析による検討

吉永治美, 小林勝弘, 秋山倫之, 岡牧郎, 伊藤美奈子

脳と発達 35 ( Suppl. ) S116 - S116 2003年5月

Epileptic spasmsを示すてんかんにおける棘波の出現に関する研究

岡牧郎, 小林勝弘, 秋山倫之, 太田穂高, 中野広輔, 岡えい次

脳と発達 34 ( Suppl. ) S105 - S105 2002年6月

Systematic source estimation of spikes by a combination of independent component analysis and RAP-MUSIC II: Preliminary clinical application 査読

K Kobayashi, T Akiyama, T Nakahori, H Yoshinaga, J Gotman

CLINICAL NEUROPHYSIOLOGY 113 ( 5 ) 725 - 734 2002年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCI IRELAND LTD

Objectives: We tried to estimate epileptic sources by a combination of independent component analysis (ICA) and recursively applied and projected multiple signal classification (RAP-MUSIC) in real epileptiform EEG discharges.
Methods: EEG data including an array of spikes from 3 patients were decomposed by ICA, and source estimation was performed by applying RAP-MUSIC to the spatial information defined by the set of ICA components that showed epileptiform activity in their waveform. Sources were also estimated from the same data using RAP-MUSIC based on eigen-decomposition of the covariance matrix of averaged spikes, and common spatial pattern decomposition for comparison.
Results: RAP-MUSIC based on ICA could estimate generally correct epileptic sources in the 3 patients, and its results were better than those of the other methods, when compared to intracerebral data. The present analysis proceeded without introduction of subjective decision after data selection. The separation of epileptiform discharges from the background is essential for this analysis, and was successfully performed in the real EEG data.
Conclusions: RAP-MUSIC based on ICA appears promising for estimation of epileptic sources with minimal dependence on subjective decisions in the process of analysis. In particular, it was not necessary to select the number of sources. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.

DOI： 10.1016/S1388-2457(02)00047-0

Systematic source estimation of spikes by a combination of independent component analysis and RAP-MUSIC I: Principles and simulation study 査読

K Kobayashi, T Akiyama, T Nakahori, H Yoshinaga, J Gotman

CLINICAL NEUROPHYSIOLOGY 113 ( 5 ) 713 - 724 2002年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCI IRELAND LTD

Objectives: We propose a combination of independent component analysis (ICA) and recursively applied and projected multiple signal classification (RAP-MUSIC) as a new approach to dipole source estimation of epileptiform discharges. The method is minimally dependent on subjective decisions.
Methods: Ten electroencephalographic (EEG) data matrices were generated by computer, each matrix including real background activity from a normal subject and an array of added simulated spikes. Each spike was a summation of two transients originating from slightly different 'original dipole sources'. The unaveraged EEG matrices were decomposed by ICA, and source estimation was performed by applying RAP-MUSIC to the spatial information defined by the ICA components showing epileptiform activity in their waveform. For comparison, dipoles were also estimated from the same matrices using two existing methods: RAP-MUSIC based on eigen-decomposition of the covariance matrices of averaged spikes and common spatial pattern decomposition.
Results: In every simulated EEG data matrix, two dipoles close to the original sources were estimated by the present method. Their unaveraged activities were also similar to those of the original sources. The two existing methods gave less precise results than the proposed method.
Conclusions: RAP-MUSIC based on ICA thus proved promising for source estimation of unaveraged epileptiform discharges. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.

DOI： 10.1016/S1388-2457(02)00046-9

Source estimation of spikes by a combination of independent component analysis and RAP-MUSIC 査読

Katsuhiro Kobayashi, Tomoyuki Akiyama, Tomoyuki Nakahori, Harumi Yoshinaga, Yoko Ohtsuka, Jean Gotman, Eiji Oka

International Congress Series 1232 ( C ) 311 - 316 2002年4月

記述言語：英語掲載種別：研究論文（学術雑誌）

We designed a combination of independent component analysis (ICA) and recursively applied and projected multiple signal classification (RAP-MUSIC) as a new approach to dipole source estimation of epileptiform discharges. The estimation is minimally influenced by subjective decisions in this analysis. A simulation study was performed by generating 10 EEG data matrices by means of a computer: each matrix included real background activity from a normal subject to which an array of simulated unaveraged spikes was added. Each discharge was a summation of two transients originating from slightly different “original dipole sources”. The simulated spikes in the unaveraged EEG data were extracted from the background by ICA as spatiotemporal components, each component having fixed potential field distribution and maximally independent waveform. The complete separation between spikes and background was objectively proven by reconstruction of the EEG from the decomposed components. RAP-MUSIC was performed based on the spatial information included in the epileptic ICA components. RAP-MUSIC does not involve subjective decisions such as selection of multiple local score peaks, determination of the number of dipoles or initial guesses of dipole parameters. In every simulated EEG data matrix, two dipoles close to the original sources were estimated. Their activities were also similar to those of the original sources. For comparison, the same simulated EEG data were averaged and subjected to RAP-MUSIC using eigen-decomposition of the covariance matrices. Only one dipole was estimated in every simulation by this conventional method and therefore the result of the present method was better. RAP-MUSIC based on ICA, thus, proved promising for source estimation of unaveraged epileptiform discharges. © 2002, Elsevier B.V.

DOI： 10.1016/S0531-5131(01)00713-0

Scopus

Photosensitive fits elicited by TV animation: An electroencephalographic study 査読

Hideo Enoki, Tomoyuki Akiyama, Junri Hattori, E. D.I. Oka

Pediatrics International 40 ( 6 ) 626 - 630 1998年

記述言語：英語掲載種別：研究論文（学術雑誌）

Background: We carried out a clinical and electroencephalographic (EEG) study to reveal the pathophysiology of acute symptoms elicited by a TV animation program. Methods: Clinical data and EEG were obtained from 20 patients ranging in age from 6 to 30 years. A pattern presentation and an intermittent photic stimulation were performed. Results: Of 20 patients, 13 had a convulsion and seven had other symptoms, mainly nausea and/or vomiting. A photoparoxysmal response (PPR) was confirmed in 12 of 13 patients (92.3%) who had a convulsion. Only one of seven patients (14.3%) without a convulsion showed a PPR. The incidence of PPR was significantly higher in patients with convulsion than those without convulsion. There were no significant differences in the family history of convulsion, gender, parameters associated with TV watching and basic EEG between the two groups. All patients with PPR had a convulsion or consciousness disturbance. Conclusion: Acute symptoms, such as convulsion and impairment of consciousness, are supposed to be based on photosensitivity. © 1998 Wiley. All rights reserved.

DOI： 10.1111/j.1442-200X.1998.tb02005.x

Scopus

Electroclinical study of localization-related epilepsies in early infancy 査読

Ohmori, I, Y Ohtsuka, E Oka, T Akiyama, S Ohtahara

PEDIATRIC NEUROLOGY 16 ( 2 ) 131 - 136 1997年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE INC

To clarify the characteristics of localization-related epilepsies in early infancy, we performed an electroclinical study of 28 epileptic patients whose first seizures occurred before 6 months of age. The patients were retrospectively divided into two groups: the seizure-controlled group (8 patients) and the refractory group (20 patients). The seizure-controlled group included the patients whose seizures were suppressed within 1 year after onset; the refractory group included all other patients. The characteristics of the refractory group were as follows: (1) most patients had serious underlying pathologies; (2) the seizure type in most cases was simple partial seizure or complex partial seizure without secondary generalization; (3) the interictal EEG showed focal abnormalities and severe dysrhythmia on the basic pattern associated with multifocal spikes in most cases; and (4) in some patients, West syndrome developed after localization- related epilepsies and generalized seizures appeared later in some cases. (C) 1997 by Elsevier Science Inc.