Norihide Maeda

Magnetic resonance imaging and positron emission tomography of band heterotopia

A case of band heterotopia was reported with findings of positron emission tomography (PET). The patient was an 8-year-old girl who had mild mental retardation and intractable partial epilepsy. Her MRI showed another diffuse layer of gray matter underlying the normal-looking cortex and separated from it by an apparently normal layer of white matter. PET scan with [18F]fluorodeoxyglucose revealed that band heterotopia had the same degree of glucose metabolism as that of the overlying cortex.

Evolutional changes of cortical hypometabolism in West's syndrome

The pathophysiological basis of the epileptic encephalopathy Wests syndrome remains unknown. We have done serial positron emission tomography (PET) with fluorine-18-labelled 2-deoxy-3-fluoro-D-glucose (FDG) in twelve patients with newly diagnosed Wests syndrome. Throughout follow-up, PET revealed diffuse or focal cortical hypometabolism in eleven patients, whereas magnetic resonance imaging (MRI) showed morphological abnormalities in only five. At disease onset, PET showed cortical hypometabolism in eight patients (diffuse in three, focal in five). The second PET showed normal metabolism in six of these patients but focal abnormalities in three of the four with normal results on first PET. In all seven patients with normal findings on the second PET, tonic spasms ceased after initial treatment and no epileptic seizure occurred thereafter. In the five patients with cortical hypometabolism on the second PET, tonic spasms persisted or recurred, or partial seizures appeared. However, in two patients PET abnormalities disappeared in accordance with the later resolution of epileptic seizures. All patients with normal MRI and second PET results had normal psychomotor development. Diffuse or focal cortical hypometabolism that cannot be detected by MRI or computed tomography is common in patients with Wests syndrome. However, this anomaly is not permanent and changes with clinical symptoms. These functional abnormalities in the cerebral cortex may be associated with the development of Wests syndrome.

Severe myoclonic epilepsy in infancy: evolution of seizures

Changes in seizure type of severe myoclonic epilepsy (SME) in infancy were reviewed retrospectively in 14 patients (11 males and 3 females) who were followed-up to the age of 7 years or more. The observation period ranged from 5 to 16 years with a mean of 10 years. During the follow-up, three or four types of seizures were seen per patient, but the pattern of appearance and disappearance of each seizure type varied considerably among the patients. Tonic-clonic convulsion, either generalized or unilateral, was seen most consistently through the entire course, and it continued to the end of follow-up in 11 patients (79%). On the contrary, myoclonic seizure, complex partial seizure, and atypical absence often disappeared and reappeared repeatedly during the course. In SME, seizure symptoms varied widely among patients in comparison with other neurological symptoms, and the most consistent core seizure type was tonic-clonic convulsions.

Cortical Hypometabolism and Delayed Myelination in West Syndrome

Summary: Purpose: We examined the relation between cortical hypometabolism and delayed myelination in patients with West syndrome (WS).

Transient focal cortical hypometabolism in idiopathic West syndrome

Positron emission tomography (PET) using 18F-labeled 2-deoxy-D-glucose was performed serially in 5 infants with idiopathic West syndrome. While tonic spasms persisted, 2 infants had hypometabolism in the bilateral temporo-parieto-occipital regions, which disappeared after cessation of spasms. In 2 other infants, PET revealed focal hypometabolism in the temporal region a few months after the disappearance of tonic spasms, but subsequent PET studies were normal. PET can detect transient metabolic abnormalities of the cerebral cortex which may be associated with the pathophysiology of West syndrome.

Focal Spasms in Clusters, Focal Delayed Myelination, and Hypsarrhythmia: Unusual Variant of West Syndrome

We report a patient who began to have clusters of seizures characterized by brief elevation of the right arm at 6 months of age. An interictal electroencephalogram (EEG) at 7 months revealed hypsarrhythmia without definite asymmetry. Simultaneous EEG and video recording disclosed that these focal spasms were associated with fast wave bursts superimposed on slow waves most markedly in the left centro-midtemporal region. The patient became seizure-free after synthetic ACTH therapy. The patient is developmentally normal at 3 years 5 months, but magnetic resonance imaging studies revealed findings suggestive of delayed myelination in the left frontal region. This patient is considered to have had an unusual variant of West syndrome associated with focal delayed myelination.

Photosensitive epilepsy in children

We performed a retrospective analysis of 17 children with photosensitive seizures (PSS) who had been followed for more than 3 years (mean: 9 years). PSS were verified in all patients by simultaneous video-EEG monitoring. The seizures were precipitated by flickering stroboscopes (14 patients) or were induced by patients themselves (3) with head-nodding in front of illumination, blinking at television or close viewing of striped patterns. PSS consisted of myoclonic seizures (eight patients), generalized tonic-clonic convulsions (5), partial seizures (3) or atypical absence (1). According to the International Classification of Epileptic Syndrome, three patients were classified as having severe myoclonic epilepsy in infancy and five as having juvenile myoclonic epilepsy. The remaining nine could not be categorized as any specific epileptic syndrome. Children with age of the onset of epilepsy at 7 years or younger tended to suffer intellectual deficit in addition to intractable seizures.

MRI findings in patients with symptomatic localization-related epilepsies beginning in infancy and early childhood.

We studied MRI findings in patients with symptomatic localization-related epilepsy (S-LRE) beginning in infancy and early childhood and their relation to some clinical features. MRI findings were investigated in 183 patients with S-LRE beginning before 6 years of age. S-LRE was defined as an epileptic syndrome manifesting with only partial seizures at least for a certain period during the clinical course, having specific neuroimaging abnormalities considered to be related to epileptic seizures, moderate or severe mental retardation, or cerebral palsy. The timing of injury was divided into the following four groups; prenatal, perinatal, postnatal and unknown. It was presumed prenatal in 56 patients (31%), perinatal in 25 (14%), postnatal in 32 (18%) and unknown in 70 (38%). The median age at the onset of partial seizures was 24 months in the congenital (prenatal and unknown) group, 39 months in the perinatal group and 25 months in the postnatal group. The onset of partial seizures was later in the perinatal group than in the congenital group. There were no significant differences in the other clinical characteristics among groups except for more frequent association of cerebral palsy in the perinatal group than in the congenital group. Our study suggests that congenital (prenatal and unknown group) disorders may be most common in patients with S-LRE beginning in infancy and early childhood. The onset of partial seizures occurred later in the perinatal group.

Clinical, EEG, and positron emission tomography features of childhood-onset epilepsy with localized cortical dysplasia detected by magnetic resonance imaging

Abstract We studied clinical, EEG, and positron emission tomography (PET) findings in 18 patients with childhood-onset epilepsy with localized cortical dysplasia detected by magnetic resonance imaging. The age at onset of epilepsy was prior to 6 months of age in about half of the patients; the oldest patient was 7 years. Unilateral dysplastic lesions were more frequently associated with partial epilepsy, whereas bilateral dysplasia was associated more with generalized epilepsy. Patients with partial epilepsy had secondarily generalized seizures more often at the onset. Two patients with partial epilepsy presented generalized seizures transiently: undetermined epilepsy with infantile spasms triggered by partial seizures in one and epilepsy with continuous spike waves during slow-wave sleep in the other. The size of the lesion was not correlated with seizure outcome but was significantly correlated with mental outcome. The PET abnormality of glucose metabolism usually corresponded to the areas of cortical dysplasia and EEG focus, but the correspondence was better in partial epilepsy than generalized epilepsy.

Simultaneous EEG-VTR and transverse topographical analyses of absence seizures in children: Some prognostic implications

The clinical symptoms and electroencephalographic (EEG) features of typical absence seizures, including transverse topographical analysis (TTA), were studied retrospectively using a simultaneous EEG-VTR system in 36 children aged between 3 and 17 years. Complex absences were more common than simple, and oral automatisms were the most frequent complex symptoms. Occurrence of complex symptoms was directly proportional to the length of seizures. There was no association between lateral TTA type and simple absences. Prognosis was favorable in patients with long seizure duration (P < 0.01), bilaterally synchronous monomorphic spike-waves throughout the seizure discharges (BSMTSD) (P < 0.005) and lateral TTA type (P < 0.05). Two different mechanisms of origin for BSMTSD/non-BSMTSD and lateral/non-lateral TTA types are probably responsible for the difference in prognosis. Favorable prognosis in patients with long seizures is discussed in relation to the duration of the illness. EEGs with BSMTSD and lateral TTA type may indicate a favorable prognosis in children with absence seizures.