Anticonvulsants in pregnancy

Managing migraine in pregnancy and breastfeeding

The disproportionate prevalence of migraine among women in their reproductive years underscores the clinical significance of migraine during pregnancy. This paper discusses how migraine evolves during pregnancy, secondary headache disorders presenting in pregnancy and puerperium, and acute and preventive options for migraine management during pregnancy and lactation. Migraine is influenced by rising estrogen levels during pregnancy and their sharp decline in puerperium. Migraine, and migraine aura, can present for the first time during pregnancy and puerperium. There is also a higher risk for the development of preeclampsia and cerebrovascular headache during these periods. New or refractory headache, hypertension, and abnormal neurological signs are important "red flags" to consider. This paper reviews the diagnostic utility of neuroimaging studies and the risks of each during pregnancy. Untreated migraine can itself lead to preterm delivery, preeclampsia, and low birth weight infants. Behavioral interventions and lifestyle modifications are the cornerstone for migraine treatment during pregnancy. In addition, one should consider the risks and efficacy of each treatment during pregnancy on an individual basis. The protective nature of breastfeeding for migraine is debated, but there is no evidence to suggest breastfeeding worsens migraine. Acute and preventive migraine treatment options are available for nursing mothers. Neuromodulation and neurostimulation devices are additional options for treatment during pregnancy and lactation, while the safety of using calcitonin gene-related peptide receptor antagonists during these times remains to be determined.

Current Status of Antiepileptic Drugs as Preventive Migraine Therapy

BACKGROUND

Antiepileptic drugs (AEDs) are an important class of agents used in the treatment of migraine, a neurological disorder that imparts significant socioeconomic burden. It is important for neurologists to understand the rationale for AEDs in migraine-preventive treatment, as well as each agent's efficacy and tolerability profile, in order to best determine clinical care.

PURPOSE OF THIS REVIEW

This article specifically provides the following: (1) a review of the mechanism of action, efficacy, and tolerability of topiramate and divalproex sodium/sodium valproate, the most widely used AEDs for migraine prevention, (2) a discussion on emerging evidence regarding the efficacy of zonisamide and levetiracetam, and (3) comments on gabapentin, pregabalin, carbamazepine, oxcarbazepine, and lamotrigine, AEDs which have insufficient evidence for use in migraine prevention.

RECENT FINDINGS

The potential role for new extended-release formulations of topiramate in migraine prevention is discussed. There is substantial evidence supporting the use of AEDs in migraine prevention. Specific agents should be chosen based on their efficacy and tolerability profiles. Further studies are needed to determine the efficacy of the newer AEDs, zonisamide and levetiracetam, in migraine prevention and to clarify the role of gabapentinoids in headache management.

Unique Populations with Episodic Migraine: Pregnant and Lactating Women

PURPOSE OF REVIEW

Migraine is a disabling and prevalent neurological disease, commonly affecting women during their reproductive years. It is crucial for providers to be able to adequately counsel women who are pregnant, planning pregnancy, or nursing, regarding preventive and abortive treatment options for episodic migraine. This review will discuss (1) the expected course of migraine during pregnancy and the post-partum period, (2) recommended preventive therapies for migraine during pregnancy and lactation, and (3) recommended abortive medications for migraine during pregnancy and lactation.

RECENT FINDINGS

Recent research has indicated safety for triptan use during pregnancy and ibuprofen use during the first trimester of pregnancy. Considerations for use of emerging migraine-preventive treatment, such as non-invasive neurostimulators, are discussed. For clinical decision-making and patient counseling, it is important to understand both the limitations in determining teratogenic effects in humans and the principles affecting medication transmission from mother to breast milk.

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.

Effects of prenatal exposure to carbamazepine on brainstem auditory evoked potentials in infants of epileptic mothers

The purpose of this study was to determine if there are any correlations between carbamazepine serum levels of epileptic mothers during pregnancy and the brainstem auditory evoked potentials in their infants as an index of drug neurotoxicity in newborns exposed prenatally. We included 20 epileptic mothers with carbamazepine medication and their 20 otherwise healthy infants. The study was conducted from September 1, 1993, to December 15, 1999. Serum carbamazepine determinations were performed monthly by enzymatic immunoanalysis in the mothers, and the averages for each trimester during pregnancy were calculated. Brainstem auditory evoked potentials were performed at 10.2 +/- 4.6 weeks of postnatal life. Pearson's correlations were calculated between carbamazepine serum levels during pregnancy and waves and interwave intervals of brainstem auditory evoked potentials. Both examinations were performed without knowledge of the results of the other investigations. No alterations in the infants' brainstem auditory evoked potentials were evident, and carbamazepine determinations were within therapeutic levels. Significant Pearson's correlations between latencies of waves III and V and third trimester of carbamazepine serum concentration levels and I-V interwave intervals to third-trimester minimum serum levels of carbamazepine were found. The findings suggest that the higher carbamazepine levels in mothers are related to increased latencies in waves III and V and I-V interwave intervals in infants subclinically, which could be an early index of fetal neurotoxicity.

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.

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.

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.

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).

Preconception care: a means of prevention

Preconceptional health promotion should provide a prevention framework for interactions with all women of childbearing potential. Preconceptional counselling is properly directed by specialists in the field of obstetrics and gynaecology, but a multispecialty effort may be needed to achieve adequate information for decision-making. Preconceptional health care offers an important opportunity for physicians involved in women's health to expand a primary care and a primary prevention focus. The obstetrician or gynaecologist is not only involved in acute diagnosis and treatment plans but also in disease prevention, risk and behaviour modification and counselling, which are integral parts of primary prevention and co-ordinated women's health care.

Epilepsy and pregnancy: a prospective study of seizure control in relation to free and total plasma concentrations of carbamazepine and phenytoin

Seizure control and plasma concentrations of antiepileptic drugs (AEDs) were determined in a prospective, population-based study of 93 pregnancies (cases) of 70 patients with epilepsy. Seventy-seven cases were treated with monotherapy, which in 70 cases consisted of carbamazepine (CBZ) or phenytoin (PHT). Dosage was kept constant unless poor seizure control prompted an increase. Plasma concentrations were determined at monthly intervals throughout pregnancy and compared with baseline levels obtained at least 10 weeks postpartum. Both free and total CBZ and PHT concentrations were analyzed. Seizure frequency during pregnancy for the group as a whole was not different as compared with the 9 pregestational months and was unaltered or improved in 85% of cases. Total CBZ concentration was slightly lower during the third trimester as compared with baseline, whereas free concentration was unchanged. In contrast, PHT levels decreased steadily as pregnancy progressed. Total plasma concentration was 39% of baseline during the third trimester, whereas free PHT concentration decreased far less, being 82% of baseline level during the third trimester. No clear-cut relation could be demonstrated between seizure control and plasma concentrations, which may be explained by the limited changes in free AED concentrations and the small number of cases with an increased seizure frequency. Our results indicate that total plasma concentrations may be misleading and that monitoring of free concentrations, in particular of PHT concentrations, may be advantageous during pregnancy.

Pregnancy, epilepsy, management and outcome: a 10-year perspective

We analysed the management and outcome of 348 pregnancies in 207 women with epilepsy from 1977 to 1981 and 1987 to 1991. Outcome was successful in 88%. There was a marked change in anticonvulsant prescribing away from phenobarbitone and phenytoin towards carbamazepine and sodium valproate but a large number of patients (24%) were treated with two or more anticonvulsants in the second cohort despite a move towards monotherapy. A significant reduction in congenital malformation (4.8%), spontaneous abortion (6.9%) or low birth weight babies (9.4%) was not seen. Until experience is gained with the newer agents, monotherapy remains of major importance in the management of the pregnant woman with epilepsy.

Hydantoin syndrome with holoprosencephaly: a possible rare teratogenic effect

We report on a newborn girl with lobar holoprosencephaly and clinical signs of hydantoin syndrome. During pregnancy the mother was treated with diphenylhydantoin and primidon for psychomotor and petit mal seizures. The possible relationship between hydantoin syndrome, holoprosencephaly, and maternal intake of anticonvulsants during pregnancy is discussed.

The effect of administration time on malformations induced by three anticonvulsant agents in C57BL/6J mice with emphasis on forelimb ectrodactyly

Exposure of C57BL/6J mice to three anticonvulsant derivatives, namely, dimethadione, sodium valproate, and sodium diphenylhydantoin, each induced postaxial forelimb ectrodactyly. The agents were administered at gestational days 9, 9 1/3, 9 2/3, and 10. It was determined that administration at day 9 2/3 induced the highest percentage of forelimb ectrodactyly for each of the three agents. The forelimb ectrodactyly response in the C57BL/6J strain was compared with the A/J strain (Collins et al., Teratology, 41:61-70, 1990); it was found that the C57BL/6J strain was more sensitive to dimethadione and the A/J strain was more sensitive to diphenylhydantoin and sodium valproate. The position of vertebral defects induced by sodium valproate correlated with the time of drug administration. The overall syndrome of malformations induced by the three anticonvulsant agents was relatively similar in the two mouse strains and differed between each of the anticonvulsant agents.