Effects of Seizures and Their Treatment on Fetal Brain

Seizure medication and planned pregnancy: balancing the risks and outcomes

INTRODUCTION

The therapeutic management of women with epilepsy (WWE) of childbearing age can be complicated by the need to balance maternal/fetal risks related to seizure occurrence during gestation with the potential teratogenic risks related to the use of anti-seizure medications (ASMs).

AREAS COVERED

The authors review clinical evidence on seizure-related and ASM-related risks during pregnancy. Current regulatory indications are discussed, evaluating their impact on clinical practice, and ethical implications of pharmacological decisions are debated.

EXPERT OPINION

If properly informed about the maternal/fetal risks carried by different pharmacological choices, WWE can become the final decision makers regarding their care in every phase of their life. Over the coming years, analysis of aggregated pregnancy registry data on the structural impact, on the fetus, of low doses of valproate and of newer ASMs, together with analysis of the main population study data on functional (cognitive and behavioral) outcomes, could lead to huge advances, making choosing an ASM a less complex process for the clinician and a less painful decision for the woman. Future objectives should include identification of the potential role of the pharmacogenomic profile of WWE in determining the risk of fetal malformations.

Pentylenetetrazol-induced seizures in adult rats are associated with plastic changes to the dendritic spines on hippocampal CA1 pyramidal neurons

Epilepsy is a chronic neurobehavioral disorder whereby an imbalance between neurochemical excitation and inhibition at the synaptic level provokes seizures. Various experimental models have been used to study epilepsy, including that based on acute or chronic administration of Pentylenetetrazol (PTZ). In this study, a single PTZ dose (60 mg/kg) was administered to adult male rats and 30 min later, various neurobiological parameters were studied related to the transmission and modulation of excitatory impulses in pyramidal neurons of the hippocampal CA1 field. Rats experienced generalized seizures 1-3 min after PTZ administration, accompanied by elevated levels of Synaptophysin and Glutaminase. This response suggests presynaptic glutamate release is exacerbated to toxic levels, which eventually provokes neuronal death as witnessed by the higher levels of Caspase-3, TUNEL and GFAP. Similarly, the increase in PSD-95 suggests that viable dendritic spines are functional. Indeed, the increase in stubby and wide spines is likely related to de novo spinogenesis, and the regulation of neuronal excitability, which could represent a plastic response to the synaptic over-excitation. Furthermore, the increase in mushroom spines could be associated with the storage of cognitive information and the potentiation of thin spines until they are transformed into mushroom spines. However, the reduction in BDNF suggests that the activity of these spines would be down-regulated, may in part be responsible for the cognitive decline related to hippocampal function in patients with epilepsy.

Peripartum hemorrhage and other obstetric and neonatal outcomes in pregnant women with epilepsy: A single-center study

OBJECTIVE

There are inconsistent results in different studies on maternal and fetal complications of pregnant women with epilepsy (PWWE). The differences may be in part due to racial characteristics. The aim of this study was to investigate if there is an increase in obstetric and neonatal complications, especially postpartum hemorrhage, in pregnant women with epilepsy in the Turkish population.

METHODS

In a tertiary center, PWWE and the control group were compared in terms of obstetric and neonatal complications as well as postpartum hemorrhage. Among 46,789 deliveries, 154 eligible PWWE were matched 1: 3 with the control group.

RESULTS

There was no increase in the possibility of peripartum hemorrhage and blood transfusion in PWWE. However, the probability of cesarean delivery was higher in PWWE (adjusted OR: 3.24 CI: 1.95-5.42, p < 0.001). Moreover, an increase in the possibility of fetal growth restriction, fetal death, admission to the neonatal intensive care unit and lower APGAR scores were found in PWWE.

CONCLUSION

Although the risk of peripartum hemorrhage does not appear to be increased in PWWE, cesarean rates and fetal complications do increase. There is also a need for prospective studies examining long-term neonatal outcomes in pregnancies complicated by epilepsy.

Effect of acute pentylenetetrazol injection induced epileptic seizures on rat dentate gyrus at different postnatal ages

Epilepsy is one of the most common neurological disorders, its prevalence approximately from 0.5% to 2% of the general population. Generalized seizures could lead to several morphological changes in the brain. This study aimed to investigate the morphological effects of a single convulsive dose of pentylenetetrazol (PTZ) on rat dentate gyrus at different postnatal ages. Thirty-six male Wistar rats were used at the following postnatal ages: P10, P21, and P90 (12 rats per each age). The animals in each age were equally divided into two groups: group I, control and group II, treated with a single intraperitoneal injection of PTZ (55 mg/kg). After confirmation of generalized tonic-clonic seizures, specimens from the right dentate gyrus were processed for light and electron microscopy. In PTZ-treated groups, the number of granule cells significantly decreased. Dark granule cells appeared in the deep layers of the granule cells in P10 and with the progress of age, they significantly increased in number and extended into the superficial layers of the granule cells. The dendritic spines diminished. Glial fibrillary acidic protein and caspase-3 expression increased. Ultrastructurally, granule cells showed irregular shaped nucleus, dilated rough endoplasmic reticulum (RER) cisternae, mitochondria with damaged cristae, large vacuoles, lysosomes, and lipofuscin granules. Dark granule cells characterized by electron-dense nucleus and cytoplasm containing disorganized Golgi bodies, swollen mitochondria with damaged cristae, numerous free ribosomes and few long strands of RER. Astrocytes had hypertrophied cell body. Acute treatment with PTZ-induced epileptic seizures caused toxic effect on the structure of rat dentate gyrus at different postnatal ages.

Generalized tonic-clonic seizures and antiepileptic drugs during pregnancy--a matter of importance for the baby?

This study investigates the impact of generalized tonic-clonic seizures (GTCS) and antiepileptic drugs (AED) during pregnancy on gestational age (GA) and anthropometric data of newborns. One hundred twenty-nine singleton pregnancies resulting in live births from September 1999 to October 2010 in 106 women with epilepsy on AED therapy, recorded within the framework of the EURAP (International Registry of Antiepileptic Drugs and Pregnancy) program at the Department of Neurology, Medical University Innsbruck, Austria, were studied. Occurrence of ≥ 1 GTCS during pregnancy was associated with a shorter GA [median (range) 37.5 [35.1-41.6] vs. 39.7 [29.1-46.3] weeks; p ≤ 0.001], an overall five times higher preterm risk (p = 0.042) and a reduced birth weight in boys (2,900 [2,050-3,870] vs. 3,205 [1,575-4,355] g; p = 0.040). In primipara, when compared to multipara, GTCS ≥ 1 significantly reduced the GA (37.9 [35.1-41.6] vs. 39.7 [29.4-44.9] weeks; p = 0.020) and raised the incidence of low birth weight (LBW) (p = 0.022) in neonates. Antiepileptic drug polytherapy significantly increased the risk for small-for-gestational-age regarding weight (SGA(W); p = 0.035) and regarding weight and/or length (SGA(W/L); p = 0.046) when compared to monotherapy. GTCS during pregnancy was associated with diverse negative effects comprising shorter GA, an increased incidence of prematurity and LBW in primiparous women. Furthermore, AED polytherapy was correlated with an enhanced risk for SGA delivery. Re-evaluating the need for drug therapy (in particular polytherapy), maintaining seizure control for a given period before pregnancy and counseling about the importance of preventing GTCS might improve pregnancy outcome in women with epilepsy.

The effect of PTZ-induced epileptic seizures on hippocampal expression of PSA-NCAM in offspring born to kindled rats

BACKGROUND

Maternal epileptic seizures during pregnancy can affect the hippocampal neurons in the offspring. The polysialylated neural cell adhesion molecule (PSA-NCAM), which is expressed in the developing central nervous system, may play important roles in neuronal migration, synaptogenesis, and axonal outgrowth. This study was designed to assess the effects of kindling either with or without maternal seizures on hippocampal PSA-NCAM expression in rat offspring.

METHODS

Forty timed-pregnant Wistar rats were divided into four groups: A) Kind+/Seiz+, pregnant kindled (induced two weeks prior to pregnancy) rats that received repeated intraperitoneal (i.p.) pentylenetetrazol, PTZ injections on gestational days (GD) 14-19; B) Kind-/Seiz+, pregnant non-kindled rats that received PTZ injections on GD14-GD19; C) Kind+/Seiz-, pregnant kindled rats that did not receive any PTZ injections; and D) Kind-/Seiz-, the sham controls. Following birth, the pups were sacrificed on PD1 and PD14, and PSA-NCAM expression and localization in neonates' hippocampi were analyzed by Western blots and immunohistochemistry.

RESULTS

Our data show a significant down regulation of hippocampal PSA-NCAM expression in the offspring of Kind+/Seiz+ (p = 0.001) and Kind-/Seiz+ (p = 0.001) groups compared to the sham control group. The PSA-NCAM immunoreactivity was markedly decreased in all parts of the hippocampus, especially in the CA3 region, in Kind+/Seiz+ (p = 0.007) and Kind-/Seiz+ (p = 0.007) group's newborns on both PD1 and 14.

CONCLUSION

Our findings demonstrate that maternal seizures but not kindling influence the expression of PSA-NCAM in the offspring's hippocampi, which may be considered as a factor for learning/memory and cognitive impairments reported in children born to epileptic mothers.

Neurobehavioral consequences of prenatal antiepileptic drug exposure

Despite elevated rates of birth defects associated with prenatal antiepileptic drug exposure, pharmacotherapy is typically continued throughout pregnancy because of the risks posed to mother and child by recurrent seizures. Emerging data suggest that prenatal exposure to valproate or polytherapy may also be associated with increased risk of cognitive impairment. However, our understanding of the longer-term sequelae of prenatal antiepileptic drug exposure remains incomplete. Improved understanding of the neurobehavioral consequences of prenatal antiepileptic drug exposure is essential to ensure accurate information is available for women with epilepsy planning a pregnancy, and to achieve optimal outcomes for mothers and children.

Social behavior impairment in offspring exposed to maternal seizures in utero

Human and animal models have demonstrated that maternal seizures in utero could be deleterious to the development of the offspring. This study focused on the social behavior of offspring exposed to seizures in utero. A pilocarpine model of temporal lobe epilepsy was induced in female Wistar rats that were mated after the first spontaneous seizure. Early after birth, pups from an epileptic mother were reared by a control mother. To evaluate the influence of the adoption process, two other groups were added: rat pups from control mothers cross-fostered with other control mothers, and rat pups reared by their birth mother. Animals exposed to seizures in utero showed impaired social behavior with no signs of anxiety-like behavior. This study demonstrated that epileptic seizures during pregnancy could be harmful to brain development and may increase the risk of developing neurodevelopmental disorders. The mechanisms underlying the abnormalities of social behavior are not well understood, and further studies in this field are warranted.

Cognitive and neurodevelopmental effects of antiepileptic drugs

This article primarily represents the contributions of two young investigators to the understanding of the neuropsychological consequences of epilepsy and its treatment. The authors have reviewed two key areas of importance: the complex relationship between cognitive dysfunction and epilepsy and the risks of cognitive dysfunction in children as a consequence of in utero exposure to antiepileptic drug treatment. The work of two young investigators is presented and future research needs are outlined.

Morphometrical study of polysialylated neural cell adhesion molecule positive cells in rat pups hippocampus following induction of seizure during pregnancy

BACKGROUND

The polysialylated neural cell adhesion molecule (PSA-NCAM) is expressed in developing brain. Fetal brain damage is caused by different conditions such as seizure and hypoxia. The present study was designed to investigate the effect of maternal seizures on the number of PSA-NCAM positive cells in pup's hippocampus.

METHODS

Female Wistar rats were divided into four groups: (a) kindled rats which received PTZ (40 mg/kg, i.p.) during pregnancy from embryonic day 14-19 (E14-E19) every 48 h, (b) kindled rats which did not receive PTZ during pregnancy, (c) non-kindle, pregnant rats which received PTZ injection (40 mg/kg, i.p.) during pregnancy from E14 to E19 every 48 h, and (d) non-kindle, pregnant rats which received injection with an equal volume of normal saline as sham controls. At postnatal day 14 (PD14), rat pups were perfused, and their brain were fixed, embedded and coronal sections stained by immunohistochemistry method. The number of PSA-NCAM positive cells per unit area in the pup's hippocampus was counted.

RESULTS

The number of PSA-NCAM positive cells in the CA1, CA3, and DG fields of pup's hippocampus, which was obtained from mothers who experienced PTZ injection during pregnancy, was decreased approximately 2.6 (P = 0.001), 2 (P = 0.001), and 2.1 (P = 0.001) times compared with non-PTZ treated maternal groups, respectively.

CONCLUSIONS

Our study showed that maternal seizures reduced the number of neurons and also PSA-NCAM positive cells per unit area in the offspring hippocampus that it may cause impairment in hippocampal functions.

Seizures during pregnancy modify the development of hippocampal interneurons of the offspring

We investigated the effect of epileptic seizures during pregnancy on hippocampal expression of calcium-binding proteins in the offspring. Female Wistar rats were submitted to the pilocarpine model and mated during the chronic period. Seizure frequency was monitored over the entire pregnancy. Pups were perfused at postnatal days 6 and 13, and the brains processed for Nissl staining and immunohistochemistry for NeuN, calbindin, calretinin, and parvalbumin. Number of stained cells in the hippocampus was estimated through stereological methods. Our results showed a decrease in epileptic seizure frequency during pregnancy. No differences were observed in NeuN-positive, CR-positive cells, and Nissl-stained hippocampal neurons between the groups. However, there was a significant decrease in calbindin-positive cells (P=0.005) and a significant increase in parvalbumin-positive cells (P=0.02) in the experimental group when compared with the control group. These results suggest that seizures during pregnancy affect the development of specific hippocampal interneurons of the offspring.

The management of epilepsy in pregnancy

While most women with epilepsy can expect a normal pregnancy outcome, epilepsy remains a significant contributor to both maternal and perinatal morbidity. Pre-pregnancy planning must address reliable contraception and optimisation of antiepileptic drug (AED) regimens to minimise teratogenic risk while maintaining seizure control. The most recent data from the AED registries regarding malformations is presented in this review, as is the limited data on the newer AEDs and studies linking neurocognitive outcomes to AED exposure. During pregnancy, important considerations include; therapeutic drug monitoring, surveillance for obstetric complications and vigilance for seizures during the intrapartum and postpartum period.

The aspects and mechanisms of cognitive alterations in epilepsy: the role of antiepileptic medications

Epilepsy is a major health problem. Several studies suggest a significant influence of epilepsy and its treatment on dynamic and functional properties of brain activity. Epilepsy can adversely affect mental development, cognition, and behavior. Epileptic patients may experience reduced intelligence, attention, and problems in memory, language, and frontal executive functions. Neuropsychological, functional, and quantitative neuroimaging studies revealed that epilepsy affect the brain as a whole. Mechanisms of epilepsy-related cognitive dysfunction are poorly delineated. Cognitive deficits with epilepsy may be transient, persistent, or progressive. Transient disruption of cognitive encoding processes may occur with paroxysmal focal or generalized epileptic discharges, whereas epileptogenesis-related neuronal plasticity, reorganization, sprouting, and impairment of cellular metabolism are fundamental determinants for progressive cognitive deterioration. Also antiepileptic drugs (AEDs) have differential, reversible, and sometimes cumulative cognitive adverse consequences. AEDs not only reduce neuronal irritability but also may impair neuronal excitability, neurotransmitter release, enzymes, and factors critical for information processing and memory. The present article serves as an overview of recent studies in adult and childhood epilepsy literatures present in PubMed that highlighted cognitive evaluation in epilepsy field (publications till 2008 were checked). We also checked the reference lists of the retrieved studies for additional reports of relevant studies, in addition to our experience in this field. Our search revealed that although the aspects of cognitive dysfunction, risk factors, and consequences have been explored in many studies; however, the mechanisms of contribution of epilepsy-related variables, including AEDs, to patients' cognition are largely unexplored. In this review, we discussed the differential effect of AEDs in mature and immature brains and the known mechanisms underlying epilepsy and AEDs adverse effects on cognition. The nature, timing, course, and mechanisms of cognitive alteration with epilepsy and its medications are of considerable clinical and research implications.

Postnatal concerns in children born to women with epilepsy

Infants born to mothers with epilepsy are at substantial risk for neurocognitive and behavioral disorders. Although exposure of the child to antiepileptic drugs (AEDs) during pregnancy and postnatally through breast milk has been implicated in disorders of higher cortical function, there have been relatively few clinical or animal studies examining the long-term effects of AEDs on cognition in the developing brain. In the limited animal studies done thus far, drug-specific effects on cognitive function have been identified. Phenobarbital, in particular, has been found to lead to adverse cognitive outcomes, whereas the newer AEDs have generally had more favorable outcomes. Although the pathophysiological mechanisms responsible for these deficits remain largely unknown, there is evidence that AEDs can adversely effect neuronal proliferation and migration, and increase apoptosis. While animal studies can provide valuable information regarding mechanism of AED-induced developmental pathology, they do not provide insight into cortical functions unique to humans, such as speech and language. Understanding the full spectrum of AED-induced effects on the developing brain will require both rigorous basic science and clinical studies.

In utero exposure to antiepileptic drugs: teratogenicity and neonatal morbidity

Clinical studies have extensively documented the various risks posed by in utero exposure to antiepileptic drugs (AEDs). However, it is difficult to sort out the extent to which any given AED is responsible for a particular outcome, given the disparities in patients taking the drugs, their type and severity of epilepsy, and the various possible AEDs, as well as the vast number of outcomes that could be assessed. This review focuses on AED exposure during pregnancy and how it affects the risks of neonatal morbidity and major congenital malformations.

Fetal Exposure to GABA-Acting Antiepileptic Drugs Generates Hippocampal and Cortical Dysplasias

PURPOSE

The management of epilepsy during pregnancy entails a number of concerns. While seizures may affect adversely maternal and fetal outcome, antiepileptic drugs (AEDs) may increase the incidence of congenital abnormalities and possibly affect postnatal cognitive development in the offspring. Experimental animal studies can aid in assessing teratogenic features associated with individual AEDs and/or with seizures, and to identify the mechanisms involved. The purpose of this study was to investigate the consequences of prenatal exposure to (a) different AEDs and (b) maternal seizures on brain maturational processes in rats.

METHODS

Pregnant rats received from embryonic days 14 to 19 intraperitoneal injections of carbamazepine (20 mg/kg/day), vigabatrin (200 mgkg/day), and valproate (100 mg/kg/day) at doses not widely different from those used clinically. Pups exposed to AEDs in utero were analyzed postnatally. Animals born to "kindled" pregnant animals that had experienced one generalized convulsive seizure per day during the same gestational period were analyzed in parallel.

RESULTS

Prenatal exposure to vigabatrin and valproate, which act on GABA signaling, induced hippocampal and cortical dysplasias, which were likely to result from a neuronal migration defect and neuronal death. By contrast, offspring of rats exposed to carbamazepine (which at the dose used produced low plasma concentrations) or to generalized convulsive seizures showed no clear-cut evidence of dysplasias.

CONCLUSIONS

We suggest that AEDs that increase the extracellular concentration of GABA might induce severe neuronal migration disorders. Drugs acting through other molecular targets would also perturb cortical maturation. The potential clinical relevance of these results should be a subject of future research.