Teratogenicity of anticonvulsant drugs. I: Review of the literature

Delivery of care, seizure control and medication adherence in women with epilepsy during pregnancy

PURPOSE

To evaluate service access for women with epilepsy (WWE) during pregnancy; to determine seizure frequency and rates of adherence to anti-seizure medication (ASM).

METHODS

Between June 2019-June 2020, pregnant WWE within NHS Greater Glasgow and Clyde health-board were identified from the National Obstetric Register. A manual review of electronic patient records was undertaken to ensure diagnostic accuracy, as well as determine contact with epilepsy services and documented seizures. Medication dispensing records were obtained six months before and six months after midwifery booking and measures of ASM adherence calculated.

RESULTS

Between June 2019-June 2020, 4592 women were registered with a pregnancy. Eighty-five (1.9%) were identified as having active epilepsy (generalised- 40/85 (47.0%), focal- 35/85 (41.2%), unclassified- 10/85 (11.8%)). Preconceptually, 42/85 WWE (49.4%) had input from epilepsy services. Only 59/85 (69.4%) were reviewed during pregnancy (First trimester- 21/59 (35.6%), Second trimester- 25/59 (42.4%) and Third trimester- 13/59 (22.0%)). Seizure occurrence was documented in 37/85 WWE (43.5%) during the antenatal/postnatal period. 71/85 WWE (83.5%) were prescribed ASM. Poor adherence was noted in 50/85 (58.9%) and a documented seizure recorded in 26/50 (52.0%) of these women.

CONCLUSION

Too many WWE do not receive input from epilepsy services during pregnancy, leaving some with poor ASM adherence and continued seizures. We aim to use "near-live" obstetric and dispensing data to facilitate early identification of WWE, promoting timely access to epilepsy specialists. This will also provide an opportunity to address concerns regarding ASM safety and allow medication dose changes to be considered.

Emerging trends and knowledge structure of epilepsy during pregnancy research for 2000-2018: a bibliometric analysis

Background

Epilepsy during pregnancy presents a unique set of challenges for pregnant women, the fetus, and the health care community. As research in this area advances rapidly, it is critical to keep up with the emerging trends and key turning points of the development of the domain knowledge. This study aimed to construct a series of science maps to quantitatively and qualitatively evaluate the intellectual landscape and research frontiers in the field of epilepsy during pregnancy research.

Methods

All publications were extracted from the Web of Science Core Collection database. Bibliometric analysis was used to analyze the scientific research outputs, including journals, countries/regions, institutions, authors (cited authors), intellectual base and research hotspots.

Results

A total of 2,225 publications related to epilepsy during pregnancy were identified as published between 2000 and 2018. The overall trend of the number of publications showed a fluctuating growth from 59 articles in 2000 to 198 in 2018. Neurology was the leading journal in the field of epilepsy and pregnancy research both in terms of impact factor score (8.055) and H-index value (77). The US retained its leading position and exerted a pivotal influence in this area. The University of Melbourne was identified as a good research institution for research collaboration. Prof. Pennell and Tomson have made great achievements in this area, and Prof. Tomson laid a foundation for the development of this domain. The keyword “neonatal seizures” ranked first in research hotspots, and the keyword “autism spectrum disorders (ASD)” ranked first in research frontiers.

Conclusions

Epilepsy during pregnancy is a fascinating and rapid development of subject matter. A more recent emerging trend focused on comprehensive management of pregnant and lactating women, evaluation of the safety and efficacy of newer antiepileptic drugs. The keywords “management issue,” “brain injury,” “meta-analysis,” “in utero exposure,” and “ASD” were the latest research frontiers and should be closely observed.

Craniofacial malformations and their association with brain development: the importance of a multidisciplinary approach for treatment

The craniofacial complex develops mainly in the first trimester of pregnancy, but its final shaping and the development of the teeth extend into the second and third trimesters. It is intimately connected with the development of the brain because of the crucial role the cranial neural crest cells play and the fact that many signals which control craniofacial development originate in the brain and vice versa. As a result, malformations of one organ may affect the development of the other. Similarly, there are developmental connections between the craniofacial complex and the teeth. Craniofacial anomalies are either isolated, resulting from abnormal development of the first two embryonic pharyngeal arches, or part of multiple malformation syndromes affecting many other organs. They may stem from gene mutations, chromosomal aberrations or from environmental causes induced by teratogens. The craniofacial morphologic changes are generally cosmetic, but they often interfere with important functions such as chewing, swallowing and respiration. In addition, they may cause hearing or visual impairment. In this review we discussed only a small number of craniofacial malformations and barely touched upon related anomalies of dentition. Following a brief description of the craniofacial development, we discussed oral clefts, craniofacial microsomia, teratogens that may interfere with craniofacial development resulting in different malformations, the genetically determined craniosynostoses syndromes and few other relatively common syndromes that, in addition to the craniofacial complex, also affect other organs. The understanding of these malformations is important in dentistry as dentists play an integral role in their diagnosis and multidisciplinary treatment.

Medical management of epileptic seizures: challenges and solutions

Epilepsy is one of the most common neurologic illnesses. This condition afflicts 2.9 million adults and children in the US, leading to an economic impact amounting to $15.5 billion. Despite the significant burden epilepsy places on the population, it is not very well understood. As this understanding continues to evolve, it is important for clinicians to stay up to date with the latest advances to provide the best care for patients. In the last 20 years, the US Food and Drug Administration has approved 15 new antiepileptic drugs (AEDs), with many more currently in development. Other advances have been achieved in terms of diagnostic modalities like electroencephalography technology, treatment devices like vagal nerve and deep-brain stimulators, novel alternate routes of drug administration, and improvement in surgical techniques. Specific patient populations, such as the pregnant, elderly, those with HIV/AIDS, and those with psychiatric illness, present their own unique challenges, with AED side effects, drug interactions, and medical-psychiatric comorbidities adding to the conundrum. The purpose of this article is to review the latest literature guiding the management of acute epileptic seizures, focusing on the current challenges across different practice settings, and it discusses studies in various patient populations, including the pregnant, geriatric, those with HIV/AIDS, comatose, psychiatric, and "pseudoseizure" patients, and offers possible evidence-based solutions or the expert opinion of the authors. Also included is information on newer AEDs, routes of administration, and significant AED-related drug-interaction tables. This review has tried to address only some of these issues that any practitioner who deals with the acute management of seizures may encounter. The document also highlights the numerous avenues for new research that would help practitioners optimize epilepsy management.

Pregnancy-related knowledge and information needs of women with epilepsy: a systematic review

For women with epilepsy (WWE), pregnancy is complicated by considerations such as the potential teratogenicity of antiepileptic drugs (AEDs) versus the risks of having seizures during pregnancy. However, qualitative research suggests that many WWE remain uninformed about the risks associated with epilepsy and pregnancy and may, therefore, be making uninformed decisions about their families. The objectives of this review were to determine the level of patient knowledge, their informational needs, and whether these needs concerning pregnancy and childbirth issues are met among WWE. Electronic databases searched were PsycINFO, MEDLINE, Embase, CINAHL, and Web of Science. Studies were included if they used quantitative methods to survey WWE aged 16years or older about their knowledge, access to information, or informational needs specifically regarding epilepsy and pregnancy. Twelve studies were identified and assessed for research standards using the Quality Index. Overall Quality Index score was only 7.1 out of 14, indicating significant design limitations of many included studies, including highly selective sampling methods and the use of unvalidated outcome measures. There was a paucity of studies investigating specific areas of women's knowledge and information needs. Overall, WWE reported adequate awareness, but limited knowledge, of key issues regarding pregnancy and childbirth. Across studies, many women reported not receiving information about these issues. Evidence suggested that many WWE wanted to receive more information - particularly about the risks of AEDs for their offspring - well in advance of choosing an AED or planning pregnancy. Women aged under 35years wanted the most information. Preconception counseling received by many WWE appears insufficient, risking uninformed decision-making about pregnancy. Further research is needed to investigate the barriers that WWE face in accessing, receiving, and retaining appropriate information.

Chronic developmental exposure to phenytoin has long-term behavioral consequences

Anti-epileptic compounds have been linked to several developmental disorders. Specifically, fetal exposure to phenytoin is linked to fetal hydantoin syndrome in humans. We have developed a rat model of fetal hydantoin syndrome in an effort to explore the relationship between drug exposure, development, and learning and memory. Previous studies of this animal model have used various embryological periods of exposure; however, the human syndrome is reported in the offspring of mothers that maintain drug regimens throughout gestation and nursing. To that end, the present study investigated associative learning in rats exposed to therapeutic levels of phenytoin throughout prenatal development and the postnatal pre-weaning period. We used an instrumental appetitive-to-aversive transfer paradigm, which has hippocampal-dependent components, and an avoidance-conditioning paradigm to test simple associative learning and higher-order learning and memory. Compared to controls, we report increased rates of acquisition and performance by the phenytoin group in both the appetitive and the avoidance learning paradigm, and a substantial impairment in avoidance learning following the transfer from appetitive to aversive conditioning. The positive deficit observed with simple associative learning and the negative transfer effect associated with higher order learning suggests that chronic exposure to phenytoin throughout gestation disrupts hippocampal development, which subsequently leads to impaired function in adulthood.

Can We Ensure the Safe Use of Known Human Teratogens?

The prescription of known teratogenic medications requires a careful balance between allowing women access to medications that they might need and avoiding unnecessary exposure to these medications during pregnancy because of their devastating fetal effects. Isotretinoin, a potent human teratogen, is of particular concern because of its widespread use among reproductive-aged women and the dramatic increase in use from 1992 through 2000. A revised risk management system was implemented in 2002 because of concerns about the continued occurrence of isotretinoin-exposed pregnancies. However, the recent approval of three generic versions of isotretinoin in the US has further complicated risk management and raises concerns that use might increase further if the lower cost of generics serves to increase accessibility. There are now four separate isotretinoin risk management systems in the US, each with its own distinct packaging, though the requirements for and substance of each are identical. Some additional concrete steps could be taken to minimise any unnecessary use of isotretinoin and help allow an adequate assessment of the current risk management systems. In addition to being familiar with and following all aspects of the current risk management system, physicians could choose to limit the use of isotretinoin to those who meet the labelled indications in order to reduce the number of exposed pregnancies. All four companies currently marketing isotretinoin in the US could jointly and voluntarily establish a consolidated, mandatory registration and follow-up of all women of reproductive potential who receive an isotretinoin prescription. Mandatory registration has many challenges, but it could allow a clear accounting of the total number of women for whom follow-up information is and is not available. Although the companies cannot be legally compelled to use a consolidated approach, the use of a single registry for the originator's product and all generic brands would allow identification of duplicates and also avoid the confusion that is introduced by providing materials that not only look different, but also have different addresses, contact information and names for participation in follow-up surveys. This is particularly important because women might take more than one version of isotretinoin during a single course of therapy or might receive a different programme's materials from their doctor than from the pharmacy. Though the introduction of generic versions of isotretinoin further complicates risk management, the companies marketing isotretinoin have an opportunity to work together to demonstrate their commitment to both limit the occurrence of exposed pregnancies and conduct a meaningful evaluation of the occurrence of pregnancies exposed to isotretinoin.

Incidence of cleft lip and palate in the northeast of Mexico: a 10-year study

In Latin American countries, studies on the incidence of cleft lip and palate are not widely available. A 10-year retrospective study was carried out to determine the incidence of cleft lip and palate at the Autonomous University of Nuevo Leon's University Hospital. The study included data from patients who attended the plastic surgery outpatient clinic from January 1990 to December 1999. The author reviewed 10,843 files from which 376 patients were selected to identify the following variables: time of the year in which the first consultation took place, gender, birthplace, type of cleft, age of both parents, and medications taken during pregnancy. The highest incidence was found in patients aged 1 to 6 months. Ninety-four patients had a primary palate cleft; 76 had a secondary palate cleft; and 206 had primary and secondary palate clefts. The gender distribution of the 206 patients with primary and secondary clefts was 127 boys and 79 girls. The mean parent age was 29.5 years (father) and 25.7 years (mother). The incidence of cleft lip and palate in the cited hospital was 1.1:1000 births. Clefts of the left side occurred more often than of the right. Boys were affected more commonly than girls.

Epilepsy and pregnancy: Report of an Epilepsy Research Foundation Workshop

Pregnancy in women with epilepsy (WWE) is known to be associated with a higher risk of congenital malformations than is associated with pregnancy in non-epileptic women. Several factors have been identified to account for the increased risk, including the direct teratogenic effects of antiepileptic drug (AED) therapy, indirect effects of these drugs by interfering with folate metabolism, genetic abnormalities in drug or folate metabolism, and possibly an arrhythmogenic effect of maternal drug therapy on the embryonic heart, leading to ischaemia in developing tissues. A harmful effect of maternal seizures on the developing embryo has not been proven, although seizures and status epilepticus account for most of the excess maternal mortality in women with epilepsy. Abrupt withdrawal of drug therapy by the mother may be an important contributory factor. Less is known about the psychomotor development of children born to mothers with epilepsy because few studies have been designed to follow their progress throughout childhood. Retrospective studies suggest that impaired cognitive development may be associated with maternal drug therapy, particularly valproate. There is an urgent need to evaluate these risks and, with this in mind, several prospective registers have been set up to collect data from pregnancies in women with epilepsy.

Ophthalmic findings in fetal anticonvulsant syndrome(s)

PURPOSE

To report the prevalence of ocular abnormalities in a group of children diagnosed with fetal anticonvulsant (FAC) syndrome(s).

DESIGN

Retrospective, observational, noncomparative case series.

PARTICIPANTS

Forty-six children, age range 8 months to 16 years 5 months (mean, 7 years 1 month), with a confirmed diagnosis of an FAC syndrome. Thirty-seven subjects were exposed in utero to sodium valproate (29 as monotherapy), and the remainder (n = 9) to other anticonvulsants, mainly carbamazepine.

METHODS

A total of 46 subjects underwent ophthalmic assessment consisting of visual acuity, cover test, ocular movements, analysis of spectacle lens power, cycloplegic refraction, and anterior segment examination with portable slit lamp, plus direct and indirect ophthalmoscopy.

MAIN OUTCOME MEASURES

Refraction and ocular motility status.

RESULTS

Thirty-one of 46 (67%) had ocular abnormalities, most commonly errors of refraction (19 of 46; 41%). Myopia was common (14 of 28; 50%) in those exposed to valproate monotherapy and there were high frequencies of strabismus (20%), astigmatism (24%), and anisometropia (11%) in the group as a whole. Thirty-one percent of myopes and 27% of astigmates did not wear glasses, of whom three subjects and two subjects, respectively, were less than 8 years old and therefore at risk of anisometropic or ametropic amblyopia. One subject had epicanthus, one color vision deficiency, and one bilateral congenital cataract.

CONCLUSIONS

We conclude that (1) abnormal ophthalmic findings are common in subjects with confirmed FAC syndrome, in particular myopia in those with fetal valproate syndrome; (2) children with FAC syndrome should receive preschool vision testing; (3) preschool vision testing should be considered in all children exposed to anticonvulsants in utero.

Drug-induced congenital defects: strategies to reduce the incidence

Approximately 1% of congenital anomalies relate to pharmacological exposure and are. in theory, preventable. Prevention consists of controlled administration of drugs known to have teratogenic properties (e.g. retinoids, thalidomide). When possible, prevention could take the form of the use of alternative pharmacological therapies during the pre-conception period for certain specific pathologies, selecting the most appropriate agent for use during pregnancy [e.g. haloperidol or a tricyclic antidepressant instead of lithium; anticonvulsant drug monotherapy in place of multitherapy; propylthiouracil instead of thiamazole (methimazole)], and substitution with the most suitable therapy during pregnancy (e.g. insulin in place of oral antidiabetics; heparin in place of oral anticoagulants; alpha-methyldopa instead of ACE inhibitors). Another strategy is the administration of drugs during pregnancy taking into account the pharmacological effects in relation to the gestation period (e.g. avoidance of chemotherapy during the first trimester, avoidance of nonsteroidal anti-inflammatory drugs in the third trimester, and avoidance of high doses of benzodiazepines in the period imminent to prepartum).

Long term health and neurodevelopment in children exposed to antiepileptic drugs before birth

OBJECTIVE

To investigate the frequency of neonatal and later childhood morbidity in children exposed to antiepileptic drugs in utero.

DESIGN

Retrospective population based study.

SETTING

Population of the Grampian region of Scotland.

PARTICIPANTS

Mothers taking antiepileptic drugs in pregnancy between 1976 and 2000 were ascertained from hospital obstetric records and 149 (58% of those eligible) took part. They had 293 children whose health and neurodevelopment were assessed.

MAIN OUTCOME MEASURES

Frequencies of neonatal withdrawal, congenital malformations, childhood onset medical problems, developmental delay, and behaviour disorders.

RESULTS

Neonatal withdrawal was seen in 20% of those exposed to antiepileptic drugs. Congenital malformations occurred in 14% of exposed pregnancies, compared with 5% of non-exposed sibs, and developmental delay in 24% of exposed children, compared with 11% of non-exposed sibs. After excluding cases with a family history of developmental delay, 19% of exposed children and 3% of non-exposed sibs had developmental delay, 31% of exposed children had either major malformations or developmental delay, 52% of exposed children had facial dysmorphism compared with 25% of those not exposed, 31% of exposed children had childhood medical problems (13% of non-exposed sibs), and 20% had behaviour disorders (5% of non-exposed).

CONCLUSION

Prenatal antiepileptic drug exposure in the setting of maternal epilepsy is associated with developmental delay and later childhood morbidity in addition to congenital malformation.

New antiepileptic drugs

BACKGROUND

Eight novel anticonvulsant drugs have been introduced in the United States in the past 10 years, as well as two new intravenous preparations of anticonvulsant drugs. The role of each in the treatment of patients with epilepsy is being refined as experience and research data accumulate.

REVIEW SUMMARY

Gabapentin, tiagabine, and oxcarbazepine are effective for partial seizures, whereas felbamate, lamotrigine, topiramate, levetiracetam, and zonisamide treat both partial and generalized seizure types. In general, these newer agents differ from older agents by relative lack of drug-drug interactions, and many show improved tolerability compared with phenytoin and carbamazepine. Each has distinguishing features that can prove useful in specific clinical situations. Despite limited Food and Drug Administration indications, all are useful in monotherapy under certain circumstances. Fosphenytoin avoids the adverse effects of intravenous phenytoin vehicle, and intravenous valproate represents a much needed option in patients who require rapid loading of this medication.

CONCLUSIONS

The greater number of antiseizure drugs available today makes it possible to tailor treatment to individual patient needs, allowing more patients to be free of debilitating adverse effects. Additionally, some patients can achieve complete seizure freedom even after failing one or more other antiepileptic drugs.

The effects of lithium, valproic acid, and carbamazepine during pregnancy and lactation

The chronic, complex, and episodic course of bipolar mood disorder presents a particularly formidable challenge to the clinician making a treatment plan for the onset or recurrence of the illness during pregnancy and lactation. Women treated with anti-manic drugs who become pregnant are commonly considered to be at high risk for fetal complications during the pregnancy or during lactation. The risks of antimanic drug use during pregnancy include teratogenic effects, direct neonatal toxicity, and the potential for longer-term neurobehavioral sequela. The use of medications during pregnancy and lactation requires critical attention to the timing of exposure, dosage, duration of use, and fetal susceptibility. The postnatal period is a time of increased onset and relapse of mental illness. No antimanic drug can be proven completely safe. Prescribing antimanic medications with a long safety record, avoiding exposure in the first trimester; avoiding multidrug regimens, and prescribing the lowest dose for the shortest duration will minimize the fetal risk. This review considers treatment with lithium, valproic acid, and carbamazepine. It assesses the risk to the fetus, the perinatal risks for the infant, the risks associated with treatment during the puerperium and breast-feeding, and the risks to the later development of the child.

Antiepileptic drugs in the 21st century

During the past 10 years, there has been a welcome influx of novel agents for the treatment of epilepsy. Many show advantages compared to older agents, including better adverse effect profiles and lack of drug-drug interactions. The sheer number of agents now available makes distinction among them confusing at times. Agents differ in spectrum of action, pharmacokinetic profile (affecting dosing schedule and drug interactions), and titration time. This review highlights the differences between the various new agents and the more traditional antiseizure drugs. Evidence for the widespread use of these compounds outside their indication, particularly for diseases other than epilepsy, is reviewed as well.

The use of anticonvulsants during pregnancy

Antiepilepsy (AED) medications have revolutionized the treatment of epilepsy, transforming it from a chronic progressive disease with inevitable cognitive and motor decline to a disorder in which most effected persons operate largely in a normal fashion. As with all medications adverse experiences can occur. However, it has been clear that the alternative of uncontrolled seizures are more hazardous than pharmacological therapies. However, physicians are faced with a dilemma when treating fertile or pregnant women with epilepsy. Many AED impair the effectiveness of oral contraceptives. There is evidence that some AED may effect fertility. AED metabolism changes in pregnancy, making management of women with epilepsy more difficult. AED exposure in early pregnancy increases the risk of congenital malformations, and exposure during other phases may increase the risk of developmental delay and neonatal hemorrhage. AED can be secreted in breast milk, thus extending the exposure into infancy. The exclusion of women of childbearing age from clinical trials limits our ability to collect information on the pharmacokinetics and potential adverse experiences of AED in pregnancy. Thus, when new medications are marketed, clinicians and their patients have no information on how to best manage conception, pregnancy, and lactation. This article discusses these issues in detail and describes our current understanding of the use of AED in women of childbearing age.

CPD-Education and self-assessment: Epilepsy and pregnancy

Pregnancies in women with epilepsy are high risk and need careful management by both the medical and obstetric teams due to the increased incidence of complications and adverse outcomes of pregnancy. By the time a pregnant woman with epilepsy presents, the foetus is virtually fully formed and the opportunity for altering drug treatment has passed. Women need to be counselled and told to seek advice about their anticonvulsant therapy should they wish to become pregnant. All major anticonvulsant drugs are teratogenic but the main risk to the developing foetus appears to be when the mother is on polytherapy especially if sodium valproate forms part of the combination. Folate supplements (5 mg) before conception are advisable. There appears to be a minor but significant increased risk of maternal complications in women with epilepsy such as hyperemesis gravidarum, pre-eclampsia and eclampsia, vaginal bleeding and premature labour. In the majority of women seizure control will not alter during pregnancy. Oral vitamin K should be given to the mother receiving enzyme-inducing antiepileptic drugs. Post-natal infant development: there is an increased risk of prematurity (9-11%), stillbirth, neonatal and perinatal death, haemorrhagic disease of the newborn, low Apgar scores and low birth weight (7-10%). Breast feeding: virtually all the anticonvulsant drugs are excreted in breast milk in low concentrations. Feeding difficulties, irritability and lethargy can occur. However, the benefits of breast feeding usually far outweigh any minor risks to the baby.

Special considerations for women with epilepsy

Women with epilepsy present health care providers with unique problems and opportunities for advancement of care. The fundamentals of epileptic pathophysiology are similar in both sexes. There are, however, some significant differences. Cosmetic effects of antiepileptic drugs (AEDs) may have different implications for women. Women who have seizures associated with their menstrual cycle may need special attention regarding their cyclic hormonal changes and AED selection. Antiepileptic drugs may reduce the effectiveness of hormonal contraception. Women with epilepsy have higher rates of infertility and an increased prevalence of reproductive and endocrine disorders. The majority of women with epilepsy have normal, healthy children, but their pregnancies are considered high risk due to an increase in seizure frequency, metabolic alterations of AEDs (which complicate management), and an increased risk of adverse pregnancy outcomes. These issues and an approach to optimize the management of women with epilepsy are discussed.

A clinical study of 57 children with fetal anticonvulsant syndromes

BACKGROUND

Anticonvulsants taken in pregnancy are associated with an increased risk of malformations and developmental delay in the children. To evaluate the pattern of abnormalities associated with prenatal anticonvulsant exposure further, we undertook a clinical study of 57 children with fetal anticonvulsant syndromes.

METHODS

Fifty two children were ascertained through the Fetal Anticonvulsant Syndrome Association and five were referred to the Aberdeen Medical Genetics Service. Pregnancy and medical history were obtained through a standardised questionnaire and interview and the children were examined.

RESULTS

Thirty four (60%) were exposed in utero to valproate alone, four (7%) to carbamazepine alone, four (7%) to phenytoin alone, and 15 (26%) to more than one anticonvulsant. Forty six (81%) reported behavioural problems, 22 (39%) with hyperactivity or poor concentration of whom four (7%) had a diagnosis of attention deficit and hyperactivity disorder. Thirty four (60%) reported two or more autistic features, of whom four had a diagnosis of autism and two of Asperger's syndrome. Forty four (77%) had learning difficulties, 46 (81%) had speech delay, 34 (60%) had gross motor delay, and 24 (42%) had fine motor delay. Nineteen (33%) had glue ear and 40 (70%) had joint laxity involving all sizes of joints. Of 46 who had formal ophthalmic evaluation, 16 (34%) had myopia.

CONCLUSIONS

Speech delay, joint laxity, glue ear, and myopia are common in the fetal anticonvulsant syndromes and autistic features and hyperactivity form part of the behavioural phenotype.

Developing diagnostic criteria for the fetal anticonvulsant syndromes

The prevalence of congenital malformations and cognitive disorders in children whose mothers took antiepileptic drugs in pregnancy is increased, compared with the background rate. Not all such cases are due to teratogenic effects of the mother's treatment. Certain problems, including neonatal withdrawal symptoms, some malformations, characteristics facial features and a typical developmental and behavioural pattern may be indicators of a probable teratogenic event. We describe a set of diagnostic criteria which may assist in defining which children are likely to have a fetal anticonvulsant syndrome. This may help future research to identify risk factors which predispose to an adverse fetal outcome.

Fetal anticonvulsant syndrome and mutation in the maternal MTHFR gene

Around 6% of infants born to mothers taking anticonvulsants have malformations, including neural tube defects, and a further proportion show developmental delay in later childhood. Three commonly used anticonvulsants, carbamazepine, phenytoin and sodium valproate, interfere with folic acid metabolism. We investigated the common 677 C>T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene in samples from 57 patients and their parents and 152 controls to determine its contribution to the risk of fetal anticonvulsant syndrome. The 677 C>T mutation frequency was significantly higher in the mothers than in the controls, but there was no significant difference in 677 C>T frequency in the patients or in the fathers. Genotype frequencies in the mothers were significantly different from controls, there being an excess of 677 C>T homozygotes. Amongst the patients, there was an apparent excess of heterozygotes (not statistically significant), and the fathers were not significantly different from controls. Mutation in the MTHFR gene in a mother taking sodium valproate, phenytoin or carbamazepine during pregnancy is associated with fetal anticonvulsant syndrome in her offspring. The skewed distribution of genotypes in the affected children probably reflects the association of fetal anticonvulsant syndrome with the maternal genotype.

Developmental neurotoxicity of phenytoin on granule cells and Purkinje cells in mouse cerebellum

Phenytoin (PHT) is a primary antiepileptic drug. Cerebellar malformations in human neonates have been described following intrauterine exposure to PHT. The neonatal period of development in the cerebellum in mice corresponds to the last trimester in humans. To examine the neurotoxic effects of PHT in the developing cerebellum, we administered PHT orally to newborn mice once a day during postnatal days 2-4. We observed many apoptotic cells in the external granular layer (EGL) on postnatal day 5, labeled cells in the EGL still remaining 72 h after labeling with 5-bromo-2'-deoxyuridine, and EGL thicker than that in the control on postnatal day 14. These results showed that PHT induced cell death of external granule cells and inhibited migration of granule cells in cerebella. In specimens immunostained with antibody against inositol 1,4,5-trisphosphate receptor type 1, Purkinje cells in the treated group had poor and immature arbors, and partially showed an irregular arrangement. The motor performance of the treated mice in a rotating rod test was impaired, although there were no changes in muscular strength or in walking pattern at the period of maturity. These findings indicate that PHT induces neurotoxic damage to granule cells and Purkinje cells in the developing cerebellum and impairs selected aspects of motor coordination ability.

Neurotoxic effects of phenytoin on postnatal mouse brain development following neonatal administration

Phenytoin (PHT) is a commonly used anticonvulsant drug. It has been reported that children exposed prenatally to PHT have brain malformations and psychomotor dysfunction. The neonatal development of the central nervous system (CNS) in mice corresponds to the last trimester in humans. To examine the neurotoxic effects of PHT on postnatal brain development, we administered PHT at doses of 10, 17.5, 25, or 35 mg/kg to newborn mice once a day during postnatal days (PD) 2-4. These dose levels result in plasma levels corresponding to the therapeutic ranges in humans. We measured the weight of total brain, cerebrum, cerebellum, and brain stem on PD 5 through 21, and examined early motor functions including head elevation, elevation of pelvis, pivoting, crawling, and righting reflex . Total brain weight, cerebral weight, and cerebellar weight in the group treated with 25 or 35 mg/kg were significantly reduced compared to controls from PD 5 to 21. Mice treated with PHT at 25 or 35 mg/kg showed decreased locomotor abilities and righting reflex on PD 5. In all phenytoin treatment groups, phenytoin levels in the brain were higher than those in the plasma on the third day of PHT treatment. We thus observed neurotoxic effects of PHT on postnatal brain development in mice. Our present data may provide useful implications for the management of PHT-induced developmental neurotoxicity and evaluation of psychomotor development in children exposed to PHT during the late fetal period.

Effects of low-dose phenytoin administered to newborn mice on developing cerebellum

To examine correlations between dose levels of phenytoin (PHT) and neurotoxic effects on cerebellar development, we administered 10, 17.5, 25, and 35 mg/kg PHT suspended in sesame oil orally to newborn Jcl:ICR mice once a day during postnatal days 2-4 and determined plasma PHT concentrations during the administration period. Mortality rates were 12.5% and 35.2% in males and 15.3% and 33.3% in females for the 25 and 35 mg/kg PHT-treated groups during the PHT treatment, respectively. In the 25 and 35 mg/kg PHT-treated groups, total brain weight, the size of the cerebellum, and cerebellar weight were significantly reduced on postnatal day 21. However, in the 10 and 17.5 mg/kg PHT-treated groups, total brain weight and the size and weight of the cerebellum did not differ from those of the control group. Histologically, the number of pyknotic cells in the external granular layer (EGL) in the 25 and 35 mg/kg PHT-treated groups was increased on postnatal day 5, and the EGL was thicker than in the control group on postnatal day 14. Some of the Purkinje cells in the 35 mg/kg PHT-treated group showed degeneration. Plasma PHT levels were 10.7 +/- 2.2 and 24.6 +/- 2.6 micrograms/ml in the 25 and 35 mg/kg PHT groups on the third day of PHT treatment, respectively. In the 25 mg/kg PHT group, plasma PHT level was found to be in the therapeutic range for humans, 10-20 micrograms/ml. Accordingly, during pregnancy, epileptic women should be carefully given PHT at the lowest effective dose while plasma PHT levels are monitored properly. These findings emphasize the importance of pharmacokinetics in evaluating of phenytoin-induced developmental neurotoxicity.

Teratogenic effects of vigabatrin in TO mouse fetuses

Vigabatrin (VGB) is a relatively recently introduced antiepileptic drug that enhances the brain levels of gamma aminobutyric acid (GABA). Few data on its teratogenic effects appear to have been reported. Our objective was to determine if VGB was teratogenic in the TO mouse. Single doses of 300-600 mg/kg of VGB dissolved in saline were administered intraperitoneally (IP) to groups of TO mice on one of gestation days (GD) 7-12. The controls were saline treated or untreated. No maternal toxic effects were observed in the 300 or 450 mg/kg groups, and the 600 mg/kg dose was totally lethal to the mothers. Fetuses were collected on GD 18. Both 300 and 450 mg/kg doses induced a consistently significant intrauterine growth retardation irrespective of the developmental stage at administration. VGB did not augment the spontaneous incidence of neural tube defects characteristic of this strain, but accelerated destruction of the brain in spontaneous exencephalic embryos. Mandibular and maxillary hypoplasia, arched palate, cleft palate (two cases), limb defects (one case), and exomphalos were observed in the malformed fetuses. The high incidence of exomphalos appears to be a unique result of VGB treatment. Alizarin red-S/alcian blue-stained, skeletons revealed hypoplasia of mid facial bones, stage-dependent increase in the frequency of cervical and lumbar ribs, rib fusion, and sternal and vertebral malformations in the drug-treated fetuses. Middle and distal phalanges of the forepaw and mid phalanges and tarsals of the hindpaw failed to ossify in a significant number of experimental fetuses. Homeotic shift in terms of presacral vertebral number and a high incidence of lumbar and cervical ribs in the treated group are suggestive of treatment-related alterations in gene expression. In view of the paucity of human and animal data on the reproductive toxicologic effects of VGB, the results of the present study assume particular importance and suggest that VGB should be used in pregnancy with extreme caution.

Spina bifida and cleft lip among newborns of Norwegian women with epilepsy: changes related to the use of anticonvulsants

OBJECTIVES

This study examined the connection between the use of anticonvulsants for epilepsy during or before pregnancy and the risk of spina bifida and cleft lip in newborns.

METHODS

Among mothers registered from 1967 to 1992 by the Medical Birth Registry of Norway, 7588 who had epilepsy were identified and their newborns' prevalence of spina bifida and cleft lip examined.

RESULTS

The odds ratio of spina bifida in children of mothers with epilepsy compared with other children increased from 1.5 in 1967 through 1980 (95% confidence interval [CI] = 0.3, 4.5) to 4.4 in 1981 through 1992 (95% CI = 2.0, 8.5). The odds ratio of cleft lip, however, decreased from 3.0 before 1981 (95% CI = 1.6, 5.1) to 1.1 after 1981 (95% CI = 0.4, 2.3).

CONCLUSIONS

This shift toward more serious birth defects is consistent with the different teratogenic effects of newer and older anticonvulsants.

Sodium valproate augments spontaneous neural tube defects and axial skeletal malformations in TO mouse fetuses [corrected]

The TO mouse exhibits a low incidence (3.65%) of spontaneous exencephaly at birth. The objectives of this study were to determine if sodium valproate (VPA) would augment this background frequency of exencephaly and to characterize its gross and histologic bases. Single doses of 200, 400, or 600 mg/kg of VPA were administered on one of gestation days (GD) 7 to 10 and fetuses were collected on GD 18. Significant augmentation of the background incidence of exencephaly was observed in the GD 7 and 8 treatment groups. Absence of the skull vault, hemorrhage, and degeneration of the exposed brain, polyhydramnios, and a female excess characterized the abnormality. Exencephalic embryos were markedly growth retarded. In addition to craniofacial and urogenital anomalies, severe axial skeletal malformations were found to be consistently associated with exencephaly. Morphometric evaluation of the alizarin red-stained skeleton confirmed significant skeletal growth inhibition. Histologic sections of GD 10 embryos revealed early onset of treatment-related growth retardation. Arrest of closure appeared to affect intermittent segments of the neural tube. The closure defect sometimes only involved the surface ectoderm of the dorsal midline. The unclosed neural tube was at times covered by a continuous layer of surface ectoderm. Cell death per se was not pronounced in the neuroepithelium. The mesenchyme was generally sparse and edema was obvious in embryos with partial closure. Growth inhibition of the optic and otic primordia was marked by pronounced cell death in these structures as well as in the otic and trigeminal ganglia and in the pharyngeal arch mesenchyme. Evidence for neural crest cell migration was also recorded. These data indicate that VPA interacts with genetic susceptibility, augments the frequency of exencephaly, and also induces other malformations in the TO mouse. The widespread malformations of the cranifacial structures are suggestive of the preferential effect of VPA on the neural crest or its derivatives.

The offspring of epileptic mother

The offspring of an epileptic mother is an issue-currently getting attention because of its several implications. A complex interaction between epilepsy during pregnancy and its adverse impact on foetus, labor, neonate, congenital malformation, psychosocial and medico-social concern and treatment challenges of such cases is increasingly being realised. Some of the significant observations has been reviewed extensively in this article. Maternal epilepsy is likely to adversely affect the off-spring at its various stages of development amounting to increased morbidity and mortality. Increased seizure frequency during pregnancy with resultant increased risk is well documented but its mechanism is poorly understood. Low apgar score, increased still birth rates (1.3 to 14%) in offspring of epileptic mother (OEM) is reported. So also, the neonatal and perinatal deaths are twice more common in OEMS than normal control. Small for dates, and prematurity in OEM is reported to be 7 to 10% and 4-11% respectively. Adverse impact on labor and delivery like preclampsia, abruptio placentae, polyhydramnios, assisted delivery, cesarean section and IUGR poses particular challenges to the obstetrician. Pediatrician's alertness is needed to anticipate and deal with the bleeding manifestation due to deficiency of Vit-K dependent clotting factors and various anticonvulsant drug (AED) withdrawal symptoms. Significant risk of developing congenital malformation is the result of epilepsy perse and the AED used during pregnancy. AED exposure leads to other distinct clinical syndromes, the orofacial clefts and cardiac anomalies being the commonest manifestation. Epilepsy in mother but not in father has significant adverse impact. Management strategies in the context of available observation has been discussed.

Serial examination of 20,248 newborn fetuses and infants: correlations between drug exposure and major malformations

Maternal medication during the first trimester of pregnancy has been discussed as a risk factor for development of birth defects. The correlation between maternal drug use and major malformations was investigated in a population-based case-control study in Mainz. Over a period of 5 years (1990-1994), 20,248 livebirths, stillbirths, and abortions underwent physical and sonographic examination, and anamnestic data were collected. A total of 1,472 births with congenital anomalies (cases) and 9,682 births without major and minor malformations (controls) were analyzed. We distinguished between 30 different drug categories, which were divided into medication taken continuously (before and during pregnancy; CM) and acute medication (drugs given within the first 3 months of gravidity; AM). Statistically highly-significant results [CM: Odds Ratios (OR) 1.2, Confidence Intervals (CI) 1.1-1.4, P = 0.008; AM: OR 1.2, CI 1.1-1.3, P = 0.008] were established for maternal drug use in correlation to birth defects. For the majority of combinations between drugs and specific malformations no teratogenic risks were found. However, statistically significant associations were recorded for antiallergics and heart anomalies (CM, AM) as well as musculoskeletal anomalies (AM); for bronchodilators and heart anomalies (CM, AM); for antiepileptics and anomalies of the internal urogenital system (CM), as well as cleft palate/cleft lips (AM); for thyroid hormones and anomalies of the nervous system (CM, AM), as well as anomalies of the external urogenital system (CM, AM); for insulin and anomalies of the musculoskeletal system (CM); for digitalis and anomalies of the musculoskeletal system (AM).

Review of the role of potential teratogens in the origin of human nonsyndromic oral clefts

Oral clefts are common birth defects affecting approximately 1 every 1,000 caucasian newborns. While many syndromes with cleft lip with or without cleft palate (CL/P) or with cleft palate (CP) are recognized, the majority of oral clefts fall into the category of "nonsyndromic oral clefts" and the etiology of this group remains incompletely understood. Investigators agree that oral clefts are multifactorial in origin, with both genetic and environmental factors in their etiology. While animal models have identified several teratogens for oral clefts, their precise relevance for humans remains unclear. The goal of this work is to review literature on environmental exposures potentially associated with non-syndromic oral clefts.

Folate metabolism and neural tube defects: a review

The importance of folate in normal fetal development and wellbeing has been recognized only during the past three decades and knowledge concerned is still far from complete. In man, folate acts as a substrate in the transfer of one-carbon moieties and thereby, plays an essential role in the synthesis of several amino acids such as methionine and nucleic acids. Consequently, folate requirements are related to the amount of tissue growth. Epidemiological, clinical and teratological research showed that this B-vitamin is particularly involved in the prevention and pathogenesis of neural tube defects. Therefore, in this review the metabolism of folate has been outlined. Furthermore, the characteristics of the various genically determined folate 'deficiencies' as well as a possible biochemical explanation of the relationship between folate and neural tube defects are being discussed. Finally, the new recommendations launched in November 1993 by the Dutch Health Council as well as the Food and Nutrition Council with regard to folate supplementation in the prevention of neural tube defects are presented.

The role of cytochrome P450 enzymes in hepatic and extrahepatic human drug toxicity

The human cytochrome P450 enzyme system metabolises a wide array of xenobiotics to pharmacologically inactive metabolites, and occasionally, to toxicologically active metabolites. Impairment of cytochrome P450 activity, which may be either genetic or environmental, may lead to toxicity caused by the parent compound itself. In practise, this usually only applies to drugs that have a narrow therapeutic index and when their clearance is critically dependent upon the fraction normally metabolised by that pathway. P450 enzymes may also convert the drug to a chemically reactive metabolite, which, if not detoxified, may lead to various forms of hepatic and extrahepatic toxicity, including cellular necrosis, hypersensitivity, teratogenicity, and carcinogenicity, depending on the site of formation and the relative stability of the metabolite, and the cellular macromolecule with which it reacts. Variation in the regulation and expression of the drug metabolising enzymes may play a key role in both interindividual variation in sensitivity to drug toxicity and tissue-specific damage. Avoidance of toxicity may be possible in rare instances by prediction of individual susceptibility or by designing new chemical entities that are metabolised by a range of enzymes (both cytochromes P450 and others) and do not undergo bioactivation.

Factors influencing the risk of abnormal pregnancy outcome in epileptic women: a multi-centre prospective study

We studied pregnancy outcome in preconceptionally recruited epileptic and control women in a multi-centre prospective non-intervention study at two university hospitals and three general hospitals. We evaluated 225 singleton pregnancies: 119 pregnancies of epileptic women who received either antiepileptic drugs (AEDs) (n = 99) or not (n = 20), and 106 pregnancies of controls. The main outcome measures were abnormal pregnancy outcome: major and minor congenital malformations, ectopic pregnancies, abortions; neonatal headcircumference; birth weight and birth length. Epileptic women had a two-fold risk of having an abnormal pregnancy outcome or an infant with minor malformations compared to healthy controls (odds ratio, with 95% confidence interval, respectively 2.1 (1.1, 4.0) and 2.0 (1.0, 4.0)). A significant correlation between the prevalence of abnormal pregnancy outcome and duration of epilepsy and AED treatment was found (risk increased by 9% (6%, 16%) per annum). No significant effect in terms of the type, the number or the serum level of the AEDs could be established. The head circumference of infants of epileptic mothers was significantly smaller (0.7 (1.2, 0.28 cm) compared to controls. An effect on the outcome of pregnancy of maternal folate supplementation or of folate blood concentrations during the periconceptional period and first trimester of pregnancy could not be determined. The severity of maternal epilepsy and/or AED treatment influences pregnancy outcome.

Effects of anticonvulsant drugs on fetal mouse palates cultured in vitro

Maxillary regions of day-12.5 ICR mouse fetuses were dissected and cultured in a chemically defined serumless medium, and the effects of anticonvulsant drugs on in vitro palatogenesis were studied. The explants were treated for 72 h in vitro with 50 to 200 micrograms/mL diphenylhydantoin (DPH), 200 to 800 micrograms/mL sodium phenobarbital (PB), 12.5 to 400 micrograms/mL sodium valproate (VPA), and 3 to 100 micrograms/mL diazepam (DAZ). During the culture, the secondary palatal shelves of control explants elevated, grew medially, and fused after 72-h culture in a manner similar to the palatogenetic process in vivo. The fusion of palatal shelves was inhibited dose-dependently by treatments with DPH, VPA, and DAZ. PB showed no significant inhibitory effects on palatal fusion at concentrations up to 800 micrograms/mL. The in vitro toxicity of the anticonvulsants tested appeared to correlate with the relative in vivo teratogenic potential of the drugs. The present study demonstrated that the in vitro organ culture system should be useful for screening teratogenic agents, especially those causing cleft palate, and for exploring the mechanisms of cleft palate formation.

The contribution of maternal epilepsy and its treatment to the etiology of oral clefts: a population based case-control study

The associations between maternal epilepsy and anticonvulsant drug therapy with the risk of oral clefts in the offspring were investigated using data from a population-based case-control study. Cases included 238 infants with cleft lip +/- cleft palate (CLP) and 107 infants with cleft palate (CP) ascertained through the Metropolitan Atlanta Congenital Defects Program (MACDP) between 1968 and 1980. Controls included 3029 population-based normal infants. Histories of maternal epilepsy and drug therapy during pregnancy were compared between cases and controls using maternal interviews and reviews of hospital medical records. Maternal epilepsy was associated with increased risk of nonsyndromic CLP (OR = 3.78, 95% C.I. 1.65-7.88), and less with CP (OR = 1.75, 95% C.I. 0.20-6.99). Therapy during pregnancy was associated with the greatest excess risk (CLP OR = 7.77, C.I. 2.02-26.0; CP OR = 3.61, C.I. 0.08-26.5). The use of polytherapy was associated with the highest risk (CLP OR = 10.5, C.I. 1.52-59.9). Adjustment for potential confounding variables in the study did not change these findings. In this well-defined population, maternal epilepsy and its treatment account for a small proportion of nonsyndromic oral clefts (attributable fraction CLP = 3.3%, CP = 0.9%).

Neurotoxicity of phenytoin administered to newborn mice on developing cerebellum

To examine the neurotoxic effects of phenytoin (PHT) on cerebellar development, we administered 50 mg/kg PHT suspended in sesame oil orally to newborn Jcl:ICR mice once a day during postnatal days 2-14 and determined plasma PHT concentrations at designated intervals during the administration period. In the treated group, walking reflex and negative geotaxis were poorly developed on postnatal day 14. Pyknotic cells in the external granular layer (EGL) significantly increased and were prominent in the vermis area compared with controls on postnatal day 14. Plasma PHT levels were 34-36 micrograms/ml on the 3rd day of PHT treatment and approached a steady-state situation. Total brain weight, size of the cerebellum, and cerebellar weight were significantly reduced in the treated group on postnatal day 56. Accordingly, oral administration of PHT in the neonatal period induced neurotoxic damage on the developing cerebellum.

Course of pregnancy and fetal outcome following maternal exposure to carbamazepine and phenytoin: a prospective study

This prospective study followed the pregnancy course of epileptic women at the Motherisk Program of The Hospital for Sick Children, Toronto. We compared fetal outcome of women treated with carbamazepine (CBZ), those treated with diphenylhydantoin (phenytoin, DPH), and a drug-free control group. Seizures were reported in 15 pregnancies; in a subgroup of 9 women without change in drug or schedule, an increase in seizure frequency was evident in 6, a decrease in 1, and no change in 2, regardless of the drug taken. Of 23 children exposed to CBZ in utero, one was born with a lumbar myelomeningocele and multiple congenital anomalies. Of 21 children exposed to DPH, there was one case of severe developmental delay and four with minor features of fetal hydantoin syndromes (FHS). The three groups did not differ in birth weights or gestational ages of the babies. Although much more experience is needed, as a result of this study and other similar reports, Motherisk now offers women treated with CBZ diagnostic tests to detect neural tube defects during the second trimester of pregnancy.

Prepregnancy care and prevention of birth defects

Birth defects and disturbances in growth and development need an increasing attention in perinatal medicine. It is remarkable that so little attention has been paid to the pathogenesis of malformations in the literature in an approach to find aspects of prevention. Primary prevention of birth defects is an important public health issue as malformations have important consequences both for society and the individuals concerned. Prepregnancy care as a logical precursor to antenatal care, offers risk-assessment, advice and occasionally treatment before pregnancy, in order to avoid congenital malformations. It is therefore that we started a research program with emphasis on primary prevention of congenital malformations. In this respect medication, maternal nutritional status, diabetes mellitus and neural tube defects are discussed.

Pregnancy and epilepsy

Women with epilepsy account for approximately 0.5% of all pregnancies. Their pregnancies are high risk because of an increased frequency of maternal seizures, complications of pregnancy, and adverse pregnancy outcomes. The increase in seizure frequency is associated with a progressive decline in antiepileptic drug (AED) levels during pregnancy even with constant dosing. Fetal deaths after a generalized seizure, although rare, have been reported, and a marked decline in fetal heart rate has been demonstrated after such seizures during delivery. AEDs have been implicated in causing a twofold increase in the rate of congenital malformations, a variety of minor physical anomalies, mostly involving the midface, and a neonatal hemorrhagic disorder. The clinician caring for a pregnant woman with epilepsy is therefore faced with a dilemma and must carefully chart a middle ground providing effective seizure control while minimizing fetal exposure to AEDs.

Differences in phenytoin biotransformation and susceptibility to congenital malformations: a review

The clinical variability of teratogenic response to fetal drug exposure has been well documented. Metabolic differences in biotransformation have been shown to extend to multiple drugs and may involve many steps in drug metabolism with alterations of key intermediates. Although metabolic differences have been reported to be associated with complications of medication use, it has only recently been appreciated that such differences also may be associated in the unborn with the potential for the disruption of normal embryologic development and the production of congenital malformations. It has long been suspected that the teratogenicity of phenytoin may be mediated not only by the parent compound, but also by toxic intermediary metabolites that are produced during the biotransformation of the parent compound. Recent work elucidating differences in isoenzyme forms of cytochrome P-450 enzyme systems, glutathione, and microsomal epoxide hydrolase has provided increased interest in the multiple individual pharmacogenetic differences that may be significant factors affecting increased susceptibility to birth defects in individuals and families with fetal exposure to phenytoin.