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Biomedical subjects

S Ohtahara

Publications and source records attributed to S Ohtahara.

At least 37 records · Page 2Linked to original sources
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

A T-to-G mutation at nucleotide pair 8993 in mitochondrial DNA in a patient with Leigh's syndrome.

We studied a patient with Leigh's syndrome using neurophysiologic, radiologic, enzymatic, biochemical, and molecular analysis. Her clinical course had started with acute encephalopathic symptoms at 7 months of age. With repeated remission and exacerbation, she developed hypotonia and symptoms of brainstem dysfunction, such as irregular respiration and swallowing difficulty. These symptoms were followed by epileptic seizures, including simple partial seizures and tonic spasms. Both serum lactate and serum pyruvate levels were elevated, and deficient activity was detected in cytochrome c oxidase in her quadriceps femoris muscle. From the early stages, we noted an abnormality in the auditory brainstem response and visual evoked potentials, and an abnormal symmetrical low-density area in the basal ganglia on the computed tomographic scan. We found a mitochondrial DNA point mutation at 8993 in blood samples from both the patient and her mother using a simple polymerase chain reaction method. The ratio of wild and mutant mitochondrial DNA calculated densitometrically on polymerase chain reaction products was 56.6% in the patient's blood cells and 8.4% in her mother's. This patient's disorder was thought to be maternally inherited Leigh's syndrome. Her brother had died of the identical clinical features at 1 year 9 months of age.

Base Composition↗
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↗
PubMed1993

Developmental and physiologic changes in cerebral blood flow velocity.

Developmental change of mean blood flow velocity (MBFV) and resistance index of the basilar artery (BA), as well as the changes in MBFV of the BA and the middle cerebral artery (MCA) during sleep and hyperventilation, were studied using transcranial Doppler sonography in healthy Japanese subjects. The MBFV of the BA increased with age from infancy through early childhood, reaching the maximum (64.4 +/- 2.6 cm/s) at the age of 5 y, and then gradually decreased. MBFV ratio of MCA to BA was almost stable between 1.57 to 1.64 in all age groups. The resistance index of the BA showed a maximum value in infants, decreased in 1- to 2-y-olds, and remained constant thereafter. The MBFV of both the MCA and BA were lower during non-rapid eye movement sleep than during wakefulness, whereas during rapid eye movement sleep they showed almost the same value as during wakefulness. They were also decreased during hyperventilation. At an expiratory CO2 level of 25 mm Hg (33.33 kPa), the average decrease in MBFV in children (n = 10) was -50.1 +/- 3.9% in the BA, and -46.2 +/- 7.4% in the MCA, significantly (p < 0.05) more marked than that in adults (n = 10) (-41.5 +/- 5.9% and -37.9 +/- 4.2%, respectively). Transcranial Doppler sonography is a noninvasive method that has a potentially wide range of applications in pediatric neurology.

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↗
PubMed1990

Long-term prognosis of the Lennox-Gastaut syndrome.

A long-term follow-up study of 89 patients of Lennox-Gastaut syndrome (LGS) disclosed the persistent occurrence of seizures in 68 patients (76.4%) and severe mental defect in 48 (53.9%). An analysis of the correlation between the mental and seizure prognoses confirmed that the persistence of minor seizures could result in mental deterioration. An examination of the evolutional changes in EEG demonstrated that diffuse slow spike-waves characteristic of LGS gradually disappeared, while focal epileptic discharges, especially multifocal spikes, appeared in spite of the persistence of minor seizures. The diagnostic criteria were satisfied in only 31 (47.0%) of 66 patients with the persistence of minor seizures. Patients with multiple independent spike foci and minor seizures were considered to belong to a specific type of epilepsy, namely the severe epilepsy with multiple independent spike foci (the severe epilepsy with MISF). The seizure and mental prognoses were poorer in patients who evolved into the severe epilepsy with MISF than others.

Adolescent↗