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Biomedical subjects

E Oka

Publications and source records attributed to E Oka.

At least 55 records · Page 3Linked to original sources
PubMed1995

Neuroepidemiological study of childhood epilepsy by application of international classification of epilepsies and epileptic syndromes (ILAE, 1989).

A population-based survey of childhood epilepsy was made in 1975 on the total population of children aged < 10 years living in Okayama Prefecture (n = 2,378 patients). Using the data obtained, we attempted to reclassify the various types of epilepsy according to the international classification (ILAE, 1989). Reclassification was possible in 1,872 (78.7%) of the 2,378 cases. The 1,872 cases consisted of 1,045 (55.8%) with localization-related epilepsies, 824 (44.0%) with generalized epilepsies, and 3 (0.2%) with epilepsies undetermined whether focal or generalized. Classification of the epilepsies in a population-based survey using the international classification involves difficulties, because both clinical and EEG findings are essential. However, if an appropriate area is selected, classification of epilepsies and epileptic syndromes in a population-based survey is possible by referring to all medical records stored at every hospital and practitioner's clinic that administers treatment to patients with epilepsy in the area.

Age Factors↗
PubMed1993

The effects of age on the N200 component of the auditory event-related potentials.

This study was undertaken to determine the effects of development and aging on N200 of event-related potentials from childhood to adulthood. Event-related potentials were recorded from 164 normal subjects ranging in age from 4 to 77 years. A total of 127 of the 164 subjects demonstrated N200 peaks. N200 showed marked developmental changes. During childhood, the N200 latency decreased rapidly with age to the minimum (217 +/- 17.3 ms) at 16 years of age, while it was prolonged gradually with age during adulthood. The latency/age slope in the subjects from 5 to 15 years of age was -9.03 ms/year, while +0.97 ms/year in those from 16 to 77. The N200-P300 interpeak latency remained constant in all age groups and showed no age-related changes. The N200 amplitude decreased as age increased. Nineteen young cases showed N200 peaks to the frequent stimuli. Their ages ranged from 5 to 17 years. Our study suggests that N200 is valuable in evaluating the developmental and aging processes in the central nervous system. The results of this study could be used as normative data in clinical practices.

Acoustic Stimulation↗
PubMed1993

Myoclonus epilepsy with ragged-red fibers: a clinical and electrophysiologic follow-up study on two sibling cases.

We performed a 5-year clinical and electrophysiologic follow-up study on two sibling cases with myoclonus epilepsy with ragged-red fibers. Both had myoclonus, intention tremor, slight muscle weakness, slight mental disturbance, hearing impairment, and optic atrophy. Neither had epileptic attacks or truncal or gait ataxia. Biochemical activity of cytochrome c oxidase was at the lower limit of the normal range of values, and an adenine to guanine transition mutation at nucleotide 8344 in the transfer RNA specific for lysine of mitochondrial DNA was detected in both cases. The electroencephalograms showed slowing of basic patterns, diffuse spike-and-wave complexes, occipital dominant wave-and-spike phantoms, 6- and 14-Hz positive spikes, and photosensitivity. No definite deterioration of basic patterns was seen, and diffuse spike-and-wave complexes and photosensitivity gradually disappeared during the slowly progressive clinical course. P2 latencies of pattern-reversal visual evoked potentials throughout the clinical course and III through V interpeak latencies of auditory brainstem responses at follow-up were prolonged without giant sensory evoked potentials in both cases.

Adolescent↗
PubMed1992

Dipole tracing in childhood epilepsy with special reference to rolandic epilepsy.

To assess the clinical applicability of dipole tracing in childhood epilepsy, the location and stability of electric source generator of focal spikes seen in EEG of epileptic children were investigated using this method. The patients were divided into 3 groups; benign childhood epilepsy with centrotemporal spikes (BCECS, Group A, n = 14), other types of epilepsy with centrotemporal spikes (Group B, n = 15) and epilepsy with focal spikes in other areas (Group C, n = 13). The spike dipole in each group was analyzed using dipole tracing method. The following results were obtained. (1) The spikes of BCECS were characterized by constantly stable dipoles, compared to those of the other types of childhood epilepsy. The spikes of epileptic children with mental retardation mostly lacked the stability of dipoles. These seemed to suggest that the stability of dipoles was closely related to the prognosis and pathophysiology of epilepsy. (2) The dipoles of BCECS were localized strictly in the Rolandic area. Dipole tracing from EEG spikes was considered to contribute to the elucidation of the pathophysiology of childhood epilepsy.

Adolescent↗
PubMed1992

Primary and secondary bilateral synchrony in epilepsy: differentiation by estimation of interhemispheric small time differences during short spike-wave activity.

Estimation of interhemispheric small time differences (TDs) during spike-wave bursts in the EEG by coherence and phase analysis is useful for differentiation between primary bilateral synchrony (PBS) and secondary bilateral synchrony (SBS) in epilepsy. Because the previous method via Fast Fourier Transform needed long bursts for reliable analysis, a method using a 2-dimensional autoregressive model was newly developed to enable estimation of TDs even in 1.2 sec bursts, and applied to 19 epileptic patients with apparently bilaterally synchronous spike-wave bursts. At the onsets of bursts, estimated maximal TDs were 5.8 msec or less and inconsistent in leading hemispheres in 10 patients with a clinical diagnosis of idiopathic, cryptogenic or symptomatic generalized epilepsy indicating PBS, while the maximal TDs were 9.3-41.5 msec and consistent in leading in 7 patients with clinically symptomatic partial epilepsy and also in two with idiopathic and symptomatic generalized epilepsy suggesting SBS. Among 8 patients with bursts which suggested SBS and long enough for evaluation of intra-burst TD variation, TDs tended to disappear in the middle to end parts of the bursts in 5 cases, but not in the other 3, suggesting 2 different pathophysiological mechanisms in SBS.

Action Potentials↗
PubMed1989

Clinical course and prognosis of childhood epilepsy.

Remarkable progress has been accomplished in epileptology in recent years. The remission rate in childhood epilepsy has been improved by the introduction of new technologies and better diagnostic as well as therapeutic methods. Investigation of prognosis is an important field of epileptology, because prognostic improvement reflects its overall progress. A long-term follow-up study of childhood epilepsy was undertaken in the Okayama University Hospital. Ten to 15 years of follow-up was possible in 730 of 1,295 patients who were first diagnosed at ages below 15 years, from 1968 to 1971. The 3-year remission rate amounted to 82.0% and 5-year remission was obtained in 79.1%. These high rates of remission indicate the favorable prognosis of childhood epilepsy. On the other hand, cases of intractable epilepsy also amounted to a considerable number. Intractable epilepsy consisted mainly of age-dependent epileptic encephalopathy (Ohtahara's syndrome, West syndrome and Lennox-Gastaut syndrome) and severe myoclonic epilepsy in infancy. Development of effective therapy for these intractable epileptic syndromes will be an important subject of future studies.

Adolescent↗
PubMed1988

Rational treatment of refractory epilepsy in childhood.

A multifaceted study on childhood refractory epilepsy disclosed an insufficient classification of epilepsies and epileptic seizures, and inappropriate polypharmacy as the most important factors preventing appropriate therapy. By means of an adjustment of AEDs based on the accurate classification of epilepsies and epileptic seizures, the number of AEDs could be reduced in 37.5% and monotherapy was successful in 13.8% of refractory cases. Most of the latter were those of partial epilepsy and generalized epilepsy with the monoseizure type. The exacerbation of seizures due to AEDs was also mentioned as one of the important side effects of AEDs.

Adolescent↗
PubMed1987

The early-infantile epileptic encephalopathy with suppression-burst: developmental aspects.

A clinico-electroencephalographic study on 14 cases of the early-infantile epileptic encephalopathy with suppression-burst (EIEE) including long-term follow-up studies for one year 8 months to 12 years 2 months disclosed the specificity of EIEE in its developmental aspects. With age, clinical evolution from EIEE to the West syndrome was observed in as many as 10 cases, among which two cases showed further transition to the Lennox-Gastaut syndrome. Electroencephalographically, suppression-burst pattern gradually began to disappear from age of 3 months and disappeared by 6 months in all the cases, transforming to hypsarhythmia in 10 cases from 2 to 6 months of age, showing further transition to diffuse slow spike-and-waves in 2 cases at one year and one month and at 3 years and one month of age, respectively. Changing pattern of EEG were classifiable into two types which strongly related to the prognosis. These findings indicated EIEE to be an independent epileptic syndrome as the earliest form of the age-dependent epileptic encephalopathy.

Electroencephalography↗
PubMed1985

Complex partial seizures in childhood.

A clinical and electroencephalographic study was undertaken on 215 children with complex partial seizures as selected on the basis of the International Classification of Epileptic Seizures (1981). Complex partial seizures were noted in 7.8% of the epileptic children. The ictal symptoms of complex partial seizures closely resembled those of psychomotor triad described by Lennox. Interictal EEG revealed seizure discharges from the temporal or frontal focus in 57.2%. There existed a group with automatism as a main symptom having both diffuse slow spike-waves and focal temporal spikes. This type should be interpreted to be one of secondary generalized epilepsies and be a variant of the Lennox syndrome.

Adolescent↗