PubMed Health⌕ Search

Biomedical subjects

E Oka

Publications and source records attributed to E Oka.

At least 37 records · Page 2Linked to original sources
PubMed1999

Dipole analysis in a case with tumor-related epilepsy.

In order to evaluate the effectiveness of presurgical dipole analysis of interictal spikes as a non-invasive technique for the determination of epileptogenic area, we compared the results of this method with those of electrocorticography (ECoG) localization in the diagnosis of a patient with tumor-related epilepsy. A preoperative MRI revealed a temporal lobe tumor on the right side. The individual dipoles estimated from the interictal spikes were located mainly in the anterolateral region of the right temporal lobe, although some were located in the mesial side. The ECoG recorded frequent spikes in the anterolateral region of the right temporal lobe consistent with the location estimated by dipole analysis. After surgery, the patient suffered from residual seizures. Therefore, the residual epileptogenic area was examined by dipole analysis using a four-layered head model instead of the previous three-layered head model. As a result, the dipole analysis was able to pinpoint the epileptic focus in the area directly adjacent to the resected area, and in the mesial temporal lobe. In conclusion, EEG dipole analysis appears to hold promise as a non-invasive presurgical evaluation technique for locating epileptogenic areas as well as for postsurgical evaluation of residual epileptic focus.

Adolescent↗
PubMed1999

Electroclinical characteristics of hemimegalencephaly.

Presented here are two long-term follow-up patients with hemimegalencephaly. Patient 1 had Ohtahara's syndrome, which evolved into West's syndrome. Patient 2 had localization-related epilepsy, which demonstrated epilepsia partialis continua throughout the clinical course. The patients' interictal electroencephalograms revealed asymmetric suppression-burst patterns sometime during the clinical course: only during early infancy in patient 1 and until the last follow-up (at 30 years of age) in patient 2. Both patients had moderate mental and motor disturbances with persistence of seizures. Hemiplegia was progressive during early childhood. Aggravation of hemiplegia might be related to frequent seizures and persistent electroencephalographic abnormalities during early childhood. Although asymmetric suppression-burst patterns are considered characteristic electroencephalographic findings in these cases, the duration of their appearance did not have definite prognostic significance.

Adolescent↗
PubMed1999

Long-term follow-up of an individual with vitamin B6-dependent seizures.

We report on a 31-year-old female with vitamin B6-dependent seizures whose seizure onset was in the neonatal period. Her elder brother had the same disorder and died in infancy. Administration of vitamin B6 was initiated in the postnatal period. At the age of 12 years 1 month, 2 months after withdrawal of vitamin B6, visual seizures began to occur frequently. Myoclonic seizures and occasional generalized convulsive seizures were also observed. At the same time, photoparoxysmal response and spontaneous diffuse spike-wave bursts were seen on her EEG. Myoclonic seizures were provoked by intermittent photic stimulation during the EEG. It is distinctive that visual seizures were one of the main seizure types in this patient, that her clinical course was relatively benign, and that she has normal intellectual outcome.

Adult↗
PubMed1999

Nonconvulsive status epilepticus in childhood localization-related epilepsy.

PURPOSE: To report on three children with localization-related epilepsy who exhibited minor seizures (atypical absences, brief atonic, and myoclonic) and nonconvulsive status epilepticus (NCSE) consisting of these minor seizures, and to elucidate their significance. METHODS: We studied the electroclinical characteristics of these children. Ictal electroencephalograms (EEGs) of NCSE were evaluated by using simultaneous video-EEG-electromyogram (EMG) polygraphic recordings. RESULTS: All patients began to have partial seizures between the ages of 6 months and 2 years 7 months, with minor seizures appearing later, between the ages of 1 year 11 months and 6 years 6 months. These minor seizures evolved into NCSE. Complex partial seizures remained after suppression of the minor seizures. Interictal EEGs taken when the minor seizures appeared showed excessive diffuse epileptic discharges in addition to multifocal spike-waves. Before and after suppression of the minor seizures, focal epileptic discharges predominated on the EEGs. On ictal EEGs of brief atonic and myoclonic seizures, diffuse spike-wave and polyspike-wave bursts were detected. Ictal EEGs of the atypical absences revealed diffuse spike-wave bursts mixed with irregular high-voltage slow waves, often interspersed with brief atonic and myoclonic seizures. When atypical absences lasted for a long time, patients manifested NCSE. Polytherapy might be related to the occurrence of minor seizures and NCSE, because all patients were treated with polytherapy at their appearance, and simplification of antiepileptic drug (AED) therapy seemed to be effective. CONCLUSIONS: We concluded that this NCSE is a type of atypical absence status which is an age-dependent, transient, electroclinical condition. The mechanism of occurrence of these minor seizures might be related to secondary bilateral synchrony.

Child↗
PubMed1998

Photosensitive fits elicited by TV animation: an electroencephalographic study.

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.

Adolescent↗
PubMed1998

Long-term follow-up of childhood epilepsy associated with tuberous sclerosis.

PURPOSE: To study the clinical and electroencephalographic (EEG) characteristics of patients whose epilepsy is associated with tuberous sclerosis, with special reference to their clinical course. METHODS: We investigated the electroclinical and radiologic features of 38 patients with epilepsy associated with tuberous sclerosis. RESULTS: Eleven patients showed only generalized epilepsy, and 10 showed only localization-related epilepsy throughout their clinical course. Among the other 17 cases, the nature of the epilepsy changed between generalized and localization-related epilepsies during the clinical course. A shift from generalized to localization-related epilepsies was more common than the reverse. Seventeen had West syndrome (WS), three had Lennox-Gastaut syndrome (LGS), and eight had epilepsies that evolved from WS to LGS. Tonic spasms, mostly in series, were seen in all 28 patients with generalized epilepsy. Eleven of the 28 patients had partial seizures and tonic spasms in the same period. Six of them showed "simultaneous seizures," consisting of tonic spasms in series and a partial seizure. Partial seizures were the main seizure type in 27 patients with localization-related epilepsy, but three of them also showed tonic spasms that included "simultaneous seizures." Ictal EEGs revealed multiple active foci in the same period that could shift during the clinical course. Neither the location nor number of tubers was related to the clinical course. As for seizure outcome, 12 (32%) of 38 patients were free from seizures at follow-up. CONCLUSIONS: In epilepsies associated with tuberous sclerosis, there may be an interrelation between generalized and localization-related epilepsies, as well as one between generalized and partial seizures.

Child↗
PubMed1998

Analysis of ictal EEGs of epilepsy associated with tuberous sclerosis.

PURPOSE: To investigate the significance of cortical pathology of tonic spasms in patients with tuberous sclerosis. METHODS: The subjects were 38 patients with epilepsy associated with tuberous sclerosis. We analyzed ictal EEGs of tonic spasms and partial seizures by means of video-EEG monitoring for a total of 763 tonic spasms in 20 patients and 107 partial seizures in 15 patients. We also investigated the relation between partial seizures and magnetic resonance imaging (MRI) findings of these patients. RESULTS: Ictal EEG patterns of tonic spasms were divided into generalized and focal patterns. Thirteen patients had only generalized patterns, whereas seven had both patterns. In five patients who had focal ictal patterns of tonic spasms and partial seizures, the location of focal patterns corresponded with the location of onset of partial seizures. Focal discharges were seen immediately before, after, and in the middle of tonic spasms in series in 13 patients. The location of focal discharges also corresponded with the location of the onset of partial seizures in 10 of the 13 patients. Regarding partial seizures, four patients had multiple active epileptogenic foci during the same period, and two others had shifting epileptogenic foci with increasing age. CONCLUSIONS: These findings indicate that cortical pathology plays an important role in the occurrence not only of partial seizures but also of tonic spasms in patients with tuberous sclerosis.

Adult↗
PubMed1998

Steady-state serum concentrations of carbamazepine and valproic acid in obese and lean patients with epilepsy.

Steady-state serum concentrations of carbamazepine (CBZ) and valproic acid (VPA) were investigated in normal weight (body mass index; BMI 20 to 25), lean (smaller than 20 BMI) and moderately obese subjects (greater than 25 BMI) who received either 400 mg/day of CBZ or 800 mg/day of VPA. The CBZ serum concentration in lean subjects was significantly higher than that in normal weight subjects. However, no significant differences in VPA serum concentration were found between the three groups. The CBZ serum concentration decreased with increases in total body weight, and the VPA serum concentration decreased with increases in ideal body weight. However, both serum concentrations were not correlated with BMI. These results suggest that VPA doses should be calculated using ideal body weight and that degree of obesity may affect CBZ serum concentration rather than VPA serum concentration.

Adolescent↗
PubMed1997

Electroclinical study of localization-related epilepsies in early infancy.

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.

Age of Onset↗
PubMed1997

Mental deterioration in childhood epilepsy.

Mental retardation is detected in 20-30% of children with epilepsy at hospitals specializing in treatment of childhood epilepsy. However, the incidence of mental deterioration in childhood epilepsy is not high. In this study, mental deterioration was found in 52 (1.8%) of the 2,880 children with epilepsy at Okayama University Hospital. The patients showing mental deterioration mostly suffered from specific epileptic syndromes, such as West syndrome, Lennox-Gastaut syndrome, severe myoclonic epilepsy in infancy and epilepsy with continuous spike-waves during slow wave sleep. These types of epilepsy show generalized electroencephalographic (EEG) abnormalities. It is presumed that mental deterioration is caused by the total effects of prolonged diffuse EEG abnormalities and the age of the patients. Antiepileptic drugs exert a relatively minor effect on mental deterioration.

Adolescent↗
PubMed1997

Cerebral blood flow velocity in handicapped children.

Using a transcranial Doppler blood flowmeter, the blood flow velocity (BFV) ratio of the middle cerebral artery (MCA) to the basilar artery (BA) was investigated in 12 patients with severe motor and intellectual disability syndrome. The BFV of the MCA was also investigated in 58 handicapped children, classified according to the severity of their motor and intellectual disability. The ratio of the MCA to the BA was lower by 2 SD from the mean of our previously reported standard value in 8 out of the 12 cases with severe motor and intellectual disability syndrome, suggesting a more profound decrease in the level of brain activity in the MCA area than that of the BA area. The BFV of the MCA mainly decreased in cases belonging to the category of the most severe motor disability (bed-ridden). Hence, it is suggested that motor disability is the main factor related to the decrease in the BFV of the MCA.

Blood Flow Velocity↗
PubMed1996

Investigation of bilateral synchronous spike-wave discharge by EEG topography.

To investigate the generator mechanism of the generalized discharge in childhood epilepsy, we studied its voltage field distribution using linked ear reference (L + R), common averaged reference (CA), and source derivation methods (SD). Two cases of epilepsy with clinical lapse of consciousness, and diffuse EEG spike-wave burst were divided into primary bilateral synchrony (PBS) and secondary bilateral synchrony (SBS), using coherence-phase analysis. Spike topograph images were shown by three different references. The difference in spike voltage between CA and SD was also investigated (CA-SD). By all three different references, PBS spike topography showed a broad symmetrical voltage gradient. In SBS, a left frontal focal negativity was shown with a steep voltage gradient in the topographic images of spikes by L + R, CA and SD. This asymmetry disappeared gradually at the end of the spike-wave burst. Both patients showed almost identical broad symmetrical voltage gradients on CA-SD topogram. EEG topography using various references suggested that the potential fields produced by deep generators were identical for PBS and SBS, although those generated by surface generators were different. These findings support the hypothesis that SBS may be projected from the subcortical system, and activated by cortical firing.

Brain↗
PubMed1996

Effects of high-dose antiepileptic drugs on event-related potentials in epileptic children.

N200 and P300 of event-related potentials (ERPs) were recorded from 22 epileptic children receiving high-dose antiepileptic drugs. The patients were undergoing monotherapy with supratherapeutic serum level and were not mentally retarded. P300 latency was prolonged in 5 of 8 patients (62.5%) of the carbamazepine (CBZ) group and in 4 of 7 patients (57.1%) of the phenytoin (PHT) group. Only one child of the PHT group showed abnormality in brain-stem auditory evoked potentials (BAEPs). Abnormality of P300 was more frequent than that of BAEP. In patients of the PHT group who underwent examinations consecutively before and after changing the dose, P300 latency was prolonged rapidly when the PHT level exceeded 30 micrograms/ml. This suggested that the prolongation was dose dependent. In all patients of the valproic acid (VPA) group, P300 latency was normal. Only 2 patients of the PHT group had P300 prolongation simultaneously with clinical signs of intoxication. Others demonstrated changes in P300 without symptoms of side effects.

Adolescent↗
PubMed1996

Partial seizures in West syndrome.

PURPOSE: To study the occurrence of partial seizures (PS) and elucidate the characteristics of patients with West syndrome (WS) with PS. METHODS: We investigated the electroclinical and radiologic features in 92 children with WS who were older than 3 years at follow-up. RESULTS: Thirty-six (39.1%) children had PS at some time during the course of the disease. They had a significantly high incidence of asymmetric spasms, hemiparesis, and asymmetric hypsarrhythmia. Their seizure prognosis was significantly less favorable. PS appeared only before spasms (group A, six children), concomitant with spasms (group B, 18 children), and only after spasms ceased (group C, 12 children). Five children in group B had PS after spasms stopped. PS in group A and during the period of active spasms in group B showed high seizure frequency and variability of both seizures and EEG manifestations. The PS and EEG epileptiform discharges were mainly in parietal-posterior temporal-occipital, and central regions. Late PSs in group B and PSs in group C were characterized by stereotyped manifestations and relatively low seizure frequency. These PSs originated mostly from frontal regions. CONCLUSIONS: In some children with WS, cortical lesions can induce both PS and spasms in series, whereas in others, both types of seizures occur with abnormally increased excitability throughout the cortex rather than as the result of a single cortical lesion. These findings suggest caution in interpreting focal discharges, which may fluctuate and are not necessarily indicative of a surgically accessible lesion. When the discharges are stable and correlate with an equally stable clinical pattern, the likelihood of an underlying cortical lesion is greater.

Age of Onset↗
PubMed1996

Mesial temporal lobe epilepsy in childhood.

To clarify the clinical picture of mesial temporal lobe epilepsy (MTLE) in childhood, we carried out a clinical, electroencephalographic, and neuroradiologic study of 19 patients. MTLE was noted in 19 (0.82%) of 2,319 epileptic patients with childhood onset. Three types of initial seizure were recognized: febrile convulsion, afebrile generalized convulsion, and complex partial seizure (CPS). As presumed causes, various prolonged convulsions (persisting for > 30 min) were found in 12 (63.2%) cases. Regardless of the presence of preceding convulsions (febrile or afebrile), the clinical course was not uniform, with CPS in the early period temporarily controlled in some cases and intractable from the early period in others. Unilateral hippocampal abnormalities were confirmed on magnetic resonance imaging (MRI) before the age of 5 years in two cases, suggesting that mesial temporal sclerosis (MTS) is formed within a relatively short period in some cases. Seizures were controlled for > 6 months in only two (10.5%) cases and persisted in 17. In four (21.1%) cases, surgical treatment was considered to be available.

Age Factors↗
PubMed1995

Spike dipole analysis using SEP dipole as a marker.

UNLABELLED: In dipole localization analysis many problems remain which affect the accuracy of localization. We performed dipole estimation of spikes and SEP components in identical patients. The subjects are 8 cases of benign childhood epilepsy with centrotemporal spikes (BCECS), and two cases of temporal lobe epilepsy (TLE). In 8 of 10 cases, we also investigated dipoles using a 3-layer model in addition to a single layer (homogenous) model. RESULTS: 1) In 8 cases of BCECS, the spike dipoles were concentrated at the central line near the SEP dipoles, at a slightly fronto-lateral-downward position to the latter. The spike dipoles seemed to be situated at the bottom of the sensory cortex. 2) In two cases of TLE, the spike dipoles were located at the same coronal plane with the SEP dipoles, and more deeply seated mesially. The spike dipoles seemed to be at the bottom of the mesial temporal area. 3) Using 3-layer models, both the spike dipoles and the SEP dipoles located more superficially, while conserving the positional relationship with each other. CONCLUSION: It is possible to more accurately define spike dipoles by using the SEP dipole as a marker.

Brain↗