Barry R. Tharp

Orbital Frontal Seizures. An Unique Electroencephalographic and Clinical Syndrome

An unique electroencephalographic pattern characterized by periodic frontal sharp slow‐waves resembling the periodic activity of SSLE was seen in three children with seizures. The seizures were associated with prominent autonomic disturbance, loud vocalization, ambulation, and automatisms. Generalized tonic‐clonic seizures never occurred despite a seizure frequency often exceeding 50/day. Depth recording at surgery in one child revealed an orbital frontal focus, and the removal of gliotic tissue in this region resulted in complete cessation of seizures and return of normal cerebral electrical activity. It is speculated that the unique clinical pattern is due to seizure discharge arising in the orbital frontal region with spread to subcortical regions, particularly the hypothalamus and to the temporal lobe.

Interburst interval measurements in the EEGs of premature infants with normal neurological outcome

Interburst intervals (IBIs) are quiescent periods of cerebral activity, which normally occur in the electroencephalograms (EEGs) of premature infants. Although it is generally felt that the duration of these intervals shorten with increasing conceptional age (CA), no systemic studies of IBIs have been done in a large group of normal premature infants with long-term follow-up and using multichannel routine EEGs. In this study, we measured the IBIs, using defined criteria, in 36 premature infants who were normal at 3 years. The IBIs were measured in 104 EEGs, obtained from these infants, using standard recording techniques. Mean and the maximum IBIs were calculated. IBI duration decreased with increasing CA, although this trend was not very prominent when very restrictive criteria for measurement of IBI length were used. Less restrictive criteria for defining an IBI led to trends which are similar to those of previous studies. Various clinical factors, such as mild encephalopathies, small intraventricular/subependymal hemorrhages, mild bronchopulmonary dysplasia, or patent ductus arteriosus did not significantly alter IBI durations. Comparison with other techniques of IBI measurement and recording are discussed. The longest period of continuous activity during a routine recording was also measured and was found to increase with increasing CA.

EEG in premature infants with intraventricular hemorrhage

Seventy-eight EEGs from 44 premature infants with CT- or autopsy-verified intraventricular hemorrhage (IVH) were reviewed retrospectively. The patients most abnormal EEG was a reliable predictor of outcome, independent of the estimated gestational age, 1- and 5-minute Apgar scores, and IVH grade. Nine of 12 infants who had all normal or mildly abnormal EEGs had favorable outcomes. The nine infants whose worst EEGs were moderately abnormal experienced mixed outcomes, ranging from normal survival to death. All 23 infants with one or more markedly abnormal EEGs suffered unfavorable outcomes. Positive rolandic sharp waves, a highly specific EEG pattern for IVH in premature infants, occurred in only 29.5% of the patients. The degree of EEG abnormality correlated significantly with the patients mental status, but not with the IVH grade. Subarachnoid hemorrhage, hypoxia-ischemia, and focal parenchymal lesions caused electrographic seizures in 14 patients, 12 of whom died (85.7%). This study suggests that EEG has limited value in the diagnosis of IVH. However, it may play an important role in the neurologic assessment of the premature infant with established IVH by confirming clinically suspected seizures and providing reliable prognostic information.

Positive rolandic sharp waves in the EEG of the premature infant

Ninety-seven EEGs from 30 premature infants found to have multifocal white matter necrosis on ultrasound (US) or autopsy were reviewed retrospectively. Twenty infants had intraparenchymal echodensities on US that developed into cystic lesions, a finding consistent with periventricular leukomalacia; 8 had intraparenchymal hemorrhages; and 2 had white matter necrosis at autopsy. Four of these infants had no intraventricular hemorrhage. Positive sharp waves in the central (rolandic) regions (PRS) were identified in 22 of these 30 infants (73%) and in 0 of 30 age-matched controls (p < 0.001). The presence of PRS on the EEG of the premature infant has a high correlation with white matter necrosis rather than with intraventricular hemorrhage. In all cases, this EEG pattern was present prior to the development of cavitations when echodensities were present on US.

Positive rolandic sharp waves in the electroencephalograms of premature neonates with intraventricular hemorrhage.

Seventy-eight electroencephalograms (EEGs) recorded from 44 premature infants with documented intraventricular hemorrhage (IVH) were retrospectively reviewed. Positive rolandic sharp waves (PRS) were observed in 13 of 44 (29.5%) patients. Among infants with grades 3 and 4 IVH, the incidence of PRS was 60% (9 of 15). During the period of study, typical PRS appeared in two EEGs of one premature infant who did not suffer an IVH. PRS were usually associated with moderately abnormal EEG backgrounds and with grades 3 and 4 IVH. Beta activity was superimposed on an average of 21.5% of PRS (beta-PRS). Infants with grades 3 and 4 IVH had a higher incidence of beta-PRS than those with smaller hemorrhages. PRS first appeared in early postnatal life, increased in abundance and then eventually disappeared from the records by 3-4 weeks of age. The field of distribution of PRS was centered at the central parasagittal region (Cz) with generous anteroposterior spread into the frontal and parietal vertices (Fz and Pz) and symmetric lateral spread into the rolandic areas (C3 and C4). Asymmetric involvement of PRS at C3 and C4 may signify differential hemispheric injury. The majority of infants whose EEGs contained PRS died or suffered serious neurologic sequelae. However, their outcomes were not significantly inferior to those without PRS.

The penicillin focus: A study of field characteristics using cross-correlation analysis

Abstract Acute epileptic foci were created by the application of penicillin to the sensorimotor cortex of twenty-one awake, paralyzed rabbits. The spikes were recorded by closely spaced cortical macro-electrodes and digitized from magnetic tape by a LINC computer. Cross-correlation functions were performed on each spike, and the cross-correlation maximal latency designated as the latency between spikes. These were compared with the latencies determined by measuring the time of peak voltage of the spike and the onset of epileptiform activity. A variety of latencies were obtained, and occasionally the distant spikes appeared to lead the focus event. The onset of the focus spike, however, always led the distant activity. The latencies measured by the cross-correlation technique and the peak voltage determination were poorly correlated with the onset time. Local application of procaine inverted the surface polarity of the focus spike but had no effect on the morphology of the distant events. Partial isolation of the focus by subpial cuts had little effect on the voltage gradient (i.e. spread). Complete 3- or 4-sided isolation was required to prevent spread; only a low voltage volume-conducted event remained beyond the isolated slab. A second focus in the intact visual cortex increased the frequency of firing of the isolated focus and frequently triggered the isolated focus. These findings suggest that the “field” of an epileptic spike is constructed of multiple independent vertical dipoles linked by short association pathways in the white matter. Ephaptic spread contributes minimally to such a field but is capable of triggering epileptiform activity even in completely isolated foci.

Prognostic value of EEG in neonatal meningitis: Retrospective study of 29 infants

Neonatal meningitis is associated with significant neurologic sequelae. Previous studies from our laboratory and others demonstrated electroencephalography (EEG) to be a useful tool in predicting long-term neurologic outcome in at-risk neonates. We, therefore, retrospectively studied 29 infants with culture-proved neonatal meningitis who died in the neonatal period or survived to follow-up at a mean of 34.4 months. Seventy-five EEGs were obtained during the acute phase of infection; the degree of EEG background abnormality proved to be an accurate predictor of outcome. Infants who had normal or mildly abnormal backgrounds had normal outcomes, whereas those with markedly abnormal EEGs died or manifested severe neurologic sequelae at follow-up. When the EEG was considered with the presence or absence of seizures and the level of consciousness, an accurate prediction of neurologic outcome was obtained in 27 infants (93%). Although the EEG patterns were generally nonspecific, some abnormalities, such as positive rolandic sharp waves, persistent hemispheric or focal voltage attenuation, suggested more specific pathology (i.e., deep white matter necrosis, large-vessel infarction and abscess, respectively). EEG was also valuable for the recognition of subtle and subclinical seizures. Therefore, we conclude that EEG is a valuable tool for predicting the long-term prognoses of infants with neonatal meningitis.

Cherry-Red Spot-Myoclonus Syndrome

Three young women, 2 of them sisters, were found to have cherry-red spots at the macula when they were children. In 1 patient the spots faded before she was 20 years old. In all 3, incapacitating myoclonus and insidious visual loss developed in adolescence. Their intellect is normal and they have no gargoyle-like features. A variety of lysosomal inclusions were noted in cortical neurons in a biopsy specimen taken from 1 patient in childhood. Liver biopsy fifteen years later revealed mucopolysaccharide-like inclusions in Kupffer cells and hepatocytes. Lipofuscin bodies were abundant in neurons and hepatocytes. The patients excrete sialic acid-containing oligosaccharides not present in normal urine, suggesting a defect in degradation of glycoproteins. The specific enzymatic defect in these patients appears to be a deficiency of lysosomal neuraminidase.

An arousal pattern in children with organic cerebral dysfunction

Abstract An unusual EEG rhythm, seen in the frontal regions during arousal from sleep, is described in 8 children ranging in age from 2 to 14 years. All had organic cerebral dysfunction, manifested as minimal cerebral dysfunction, or a seizure disorder. It is suggested that the arousal state deserves study in all children utilizing montages containing the frontal electrodes.

An Overview of Pediatric Seizure Disorders and Epileptic Syndromes

Summary: Seizures are common in infants and children and must be differentiated from a wide variety of other neurological and nonneurological disorders which include episodic disturbances of behavior. If the diagnosis is clear, then one must decide if the seizure is an isolated event and unlikely to recur (as are many afebrile generalized convulsive seizures in early childhood), a symptom of underlying cerebral pathology, or part of an epileptic syndrome. The latter may be a potentially lethal neurodegenerative disease or a benign epilepsy with excellent outcome. This review will discuss the various aspects of epilepsy in the pediatric age group, emphasize the benign nature of most seizures in children (including many forms of partial, or focal, seizures), and present an overview of the more serious epileptic syndromes. The myoclonic epilepsies will be used as a model to illustrate the wide scope of epileptic phenomena in infants and children.