Slow sleep oscillation, rhythmic K-complexes, and their paroxysmal developments

This paper presents the relations between the slow (< 1 Hz) oscillation (characterizing the activity of corticothalamic networks during quiescent sleep in cats and humans), sleep K-complexes, and some paroxysmal developments of sleep patterns. At the cellular level, the slow oscillation is built up by rhythmic membrane depolarizations and hyperpolarizations of cortical neurons. The EEG expression of this activity is marked by periodic K-complexes which reflect neuronal excitation. The slow oscillation triggers, groups and synchronizes other sleep rhythms, such as thalamically generated spindles as well as thalamically and cortically generated delta oscillations. We discuss the distinctness of the slow (< 1 Hz) and delta (1–4 Hz) oscillations. We also show that the slow cortical oscillation underlies the onset of spike-wave seizures during sleep by transforming the periodic K-complexes into recurrent paroxysmal spike-wave complexes.     

Effect of generalized seizures on the structure of the sleep-waking cycle and the EEG in rats with an inherited predisposition to audiogenic convulsions

Data are presented on the effects of generalized tonic-clonic seizures on the structure of the one-day sleep-waking cycle in Krushinskii-Molodkina (KM) rats, which have a genetic predisposition to audiogenic convulsions. Spectral and correlation analysis of EEG activity in the hippocampus, caudate nucleus, medial central nucleus of the thalamus, and in the somatosensory, visual, and auditory regions of the cortex of these animals was carried out for time intervals before and after convulsions. After seizures, rats showed a prolonged (up to 3.5 h) reduction in fast-wave sleep (FWS) with no subsequent compensatory increase in this shase in the sleep-waking cycle, while a disturbance in slow-wave sleep (SWS) was minor and short-lived (not more than 2 h). It is suggested that generalized paroxysmal attacks predominantly involve disorganization of the function of the systems regulating FWS, while the synchronizing mechanisms of the brain, responsible for SWS, are affected to a lesser extent. Laboratory of the Evolution of Sleep and Waking (Director G. A. Oganesyan), I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg. Translated from Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 81, No. 10, pp. 1–8, October, 1995.     

Recombinant congenic strains of mice from B10.D2 and DBA/2: Their contribution to behavior genetic research and application to audiogenic seizures

Recombinant congenic strains (RCS) represent a series of related strains, each of which carries a small fraction of the genome of one strain (donor strain) on the genetic background of another strain (background strain). Recombinant inbred strains (RIS) are commonly used to identify major gene segregation and linkage and associations between behavior and quantitative trait loci, whereas recombinant congenic strains (RCS) open other complementary leads. The variability in the reactivity of RCS to a trait is thus the expression of few minor-effect genes originating from the donor strain, because the probability that major genes are present in any one RCS is low. Unlike RIS in which minor-effect genes are often masked by major genes, RCS enable the effects of minor genes to be studied. With our method, for a given trait, an estimate can be made of the gene strength distribution as well as an estimate of the minimal number of genes involved having a certain strength.This study was supported by the Centre National de la Recherche Scientifique (URA 1924 and CSEAL-UPS 44, CNRS), Université René-Descartes, Paris V UFR Biomédicale, and the Fondation pour la Recherche Médicale.     

Partial epilepsy in neurologically normal children: clinical syndromes and prognosis

A clinical and electroencephalographic study of 107 neurologically normal children with partial seizures was undertaken to verify the existence and determine the frequency of epileptic syndromes reported in selected populations. Sixty-three children had simple partial seizures, 39 had complex partial seizures, and 5 children were unclassifiable. The syndrome of benign partial epilepsy of children with rolandic spikes (BPEC, 38 cases) was clearly identified and its uniformly benign final prognosis was confirmed even if some of these children had at times severe or poorly controlled seizures. Among the children with simple partial seizures outside the BPEC (25 cases) and complex partial seizures (39 cases), no homogeneous clinical or electroclinical subgroup could be found. Two children with benign partial epilepsy and myoclonic-astatic seizures ("atypical benign partial epilepsy of childhood") and one child with "benign epilepsy with occipital spike-waves" were identified. 74% of children with epilepsy with complex partial seizures (ECP) had a 1-year seizure-free interval, and many children with epilepsy with simple partial seizures outside the BPEC group (ESP) had no more than two seizures. A benign course is thus not limited to the BPEC but is difficult to predict. Prospective studies are necessary to confirm the existence of well-defined benign syndromes among the idiopathic partial epilepsies of childhood, which appear quite rare outside the BPEC.     

Safety of measles and pertussis-containing vaccines in children with autism spectrum disorders

ObjectivesTo determine whether children aged 4–7 years with a diagnosis of autism spectrum disorders (ASD) were at increased risk of fever, febrile seizures, or emergency department (ED) visits following measles- or pertussis-containing vaccines compared with children without ASD.MethodsThe study included children born between 1995–2012, aged 4–7 years at vaccination, and members of six healthcare delivery systems within Vaccine Safety Datalink. We conducted self-controlled risk interval analyses comparing rates of outcomes in risk and control intervals within each group defined by ASD status, and then compared outcome rates between children with and without ASD, in risk and control intervals, by estimating difference-in-differences using logistic regressions.ResultsThe study included 14,947 children with ASD and 1,650,041 children without ASD. After measles- or pertussis-containing vaccination, there were no differences in association between children with and without ASD for fever (ratio of rate ratio for measles-containing vaccine = 1.07, 95% CI 0.58–1.96; for pertussis-containing vaccine = 1.16, 95% CI 0.63–2.15) or ED visits (ratio of rate ratio for measles-containing vaccine = 1.11, 95% CI 0.80–1.54; for pertussis-containing vaccine = 0.87, 95% CI 0.59–1.28). Febrile seizures were rare. Pertussis-containing vaccines were associated with small increased risk of febrile seizures in children without ASD.ConclusionChildren with ASD were not at increased risk for fever or ED visits compared with children without ASD following measles- or pertussis-containing vaccines. These results may provide further reassurance that these vaccines are safe for all children, including those with ASD.     

Role of cutaneous feedback in ventral rubbing in the male Mongolian gerbil

Increased arousal levels in pregnant rats were produced via electrical stimulation of the reticular formation (RF) on Days 6–16 of gestation. Current levels between 0.02 and 0.06 mA were selected depending on the threshold for overt motor response to stimulation in the individual animal. Offspring were tested at 30 days of age for threshold of flurothyl-induced convulsion, and at 90 days of age for percent avoidance in a shock avoidance task. In comparison to offspring of implanted controls, RF-stimulated offspring had elevated seizure thresholds (males and females) and enhanced avoidance performance (females only). Further studies using fostering showed that the effect on avoidance performance was mediated both prenatally and postnatally. The relative importance of prenatal and postnatal influences on seizure threshold could not be determined. These results are compared to previous studies of the behavioral effects of prenatal chlorpromazine threatment.     

Nocturnal Paroxysmal Dystonia with Short-Lasting Attacks: Three Cases with Evidence for an Epileptic Frontal Lobe Origin of Seizures

The epileptic or nonepileptic origin of nocturnal paroxysmal dystonia (NPD) has been debated. We studied three patients with frequent attacks during non-REM sleep. During prolonged video-EEG monitoring, two patients had a convulsive seizure after a typical NPD episode and on these occasions EEG showed epileptiform discharge. In the three patients, attacks occurred repeatedly with different intensity, representing "fragments" of the same seizure. These fragments of the attack could occur periodically every 20-40 s. We postulate that short NPD attacks are actually epileptic seizures originating from the frontal lobes. The rhythmicity of the episodes may be due to rhythmic oscillation of cortical function during non-REM sleep.     

Pharmacodynamics of Phenobarbital Anesthesia and Pentylenetetrazol-Induced Maximal Seizures in a Rat Model of Neoplastic Spinal Cord Compression

The purpose of this investigation was to determine whether paraplegia induced by neoplastic cord compression affects the pharmacodynamics of phenobarbital general anesthesia or of pentylenetet-razol (PTZ)-induced convulsions. Paraplegic rats harboring a thora-columbar epidural tumor, or an identical hindlimb tumor mass, received an i.v. infusion of phenobarbital until the onset of anesthesia. At that point, the phenobarbital concentrations in the CSF and serum were measured. Similarly, PTZ was infused until the onset of maximal seizures. It was found that changes related to systemic tumor growth and newly developed paraplegia due to neoplastic spinal cord compression did not attenuate the pharmacodynamics of phenobarbital. However, sustained paraplegia of 4 days duration reduced CNS sensitivity to the hypnotic action of the barbiturate as evidenced by the higher cerebrospinal fluid phenobarbital concentration required to induce anesthesia (170 ± 31 vs 125 ± 20 mg/L; P < 0.05). On the other hand, sustained paraplegia did not affect brain threshold concentration for PTZ-induced seizures.     

Hypnotic recall: a positive criterion in the differential diagnosis between epileptic and pseudoepileptic seizures

PURPOSE: Because the diagnosis of pseudoepileptic seizures (PESs) is mostly made by excluding epilepsy, availability of a positive criterion for PESs is of great importance. This study was aimed at the validation of a diagnostic technique that intends to provide in such a positive criterion. METHODS: In 17 patients with epileptic seizures (ESs) and 20 patients with PESs, a hypnotic procedure was performed by an investigator blind to other data to recover amnesia for the ictus. If recall was obtained, the experimental diagnosis PES was given; if not, ES was diagnosed. The experimental diagnoses were compared with the clinical, EEG-confirmed diagnoses. Hypnotizability was measured to determine the relation between the outcome of the test and hypnotizability of the patients. RESULTS: Recall for the ictus was obtained in 17 patients. Each of these had a clinical diagnosis of PES. Seventeen patients with "no recall" had a clinical diagnosis of ES, and three patients had PESs. This result yields a specificity of 100% and a sensitivity of 85% for the recall technique. Hypnotizability was significantly higher in patients with PESs than in patients with ESs. In some "low hypnotizables," recall was obtained, and in some "high hypnotizables," no recall was obtained. CONCLUSIONS: A positive recall test indicates PES. A sub-group of patients with PESs is characterized by a high level of hypnotizability. Hypnotizability is not crucial for outcome of the recall test. High hypnotic abilities are especially found in disorders in which it is supposed that "dissociation" is involved. It can be speculated that PES may be one of the dissociative phenomena.