Visual and ocular outcome in children after prenatal exposure to antiepileptic drugs

Sex differences and risk factors for bleeding in Alagille syndrome

Spontaneous bleeds are a leading cause of death in the pediatric JAG1-related liver disease Alagille syndrome (ALGS). We asked whether there are sex differences in bleeding events in patients, whether Jag1^Ndr/Ndr mice display bleeds or vascular defects, and whether discovered vascular pathology can be confirmed in patients non-invasively. We performed a systematic review of patients with ALGS and vascular events following PRISMA guidelines, in the context of patient sex, and found significantly more girls than boys reported with spontaneous intracranial hemorrhage. We investigated vascular development, homeostasis, and bleeding in Jag1^Ndr/Ndr mice, using retina as a model. Jag1^Ndr/Ndr mice displayed sporadic brain bleeds, a thin skull, tortuous blood vessels, sparse arterial smooth muscle cell coverage in multiple organs, which could be aggravated by hypertension, and sex-specific venous defects. Importantly, we demonstrated that retinographs from patients display similar characteristics with significantly increased vascular tortuosity. In conclusion, there are clinically important sex differences in vascular disease in ALGS, and retinography allows non-invasive vascular analysis in patients. Finally, Jag1^Ndr/Ndr mice represent a new model for vascular compromise in ALGS.

Modified Xenopus laevis approach (R-FETAX) as an alternative test for the evaluation of foetal valproate spectrum disorder

In compliance to animal welfare 3Rs principle there is a great demand for refined tests alternative to classical mammal teratogenicity tests. We propose a refined alternative amphibian method (R-FETAX) to evaluate chemical induced embryotoxicity. The human foetal valproate spectrum disorder (FVSD) characteristics are morphological defects (including cranio-facial, neural tube defects) and behavioural alterations due to valproate (VPA) exposure in pregnancy. Vertebrate assays to evaluate FVSD include classical and alternative mammal (implying adult sacrifice), and non-mammal developmental models (zebrafish, amphibians, chick). Among these latter only zebrafish assays report in the same test both morphological and behavioural examinations. Compared to zebrafish, the amphibian Xenopus laevis excels having a more comparable organ development and morphology to mammalian systems. We used X. laevis embryos exposed during developmental specific windows to VPA therapeutic concentrations. Different VPA effects were observed depending on the exposure window: concentration-related embryo-lethal and teratogenic effects (neural tube, facial, tail defects) were observed in groups exposed at the organogenetic phylotypic stages. Neurobehavioral deficits were described using a functional swimming test at the highest VPA concentration exposure during the phylotypic stages and at any concentration during neurocognitive competent stages. Malformations were compared to those obtained in a mammalian assay (the rat post-implantation whole embryo culture method, WEC), that we used in the past to evaluate VPA teratogenicity. R-FETAX and WEC data were modelled and their relative sensitivity was calculated. We suggest the amphibian R-FETAX as a refined windowed alternative test for the evaluation of chemicals inducing both morphological and behavioural anomalies, including VPA.

Teratogenic effects of carbamazepine on embryonic eye development in pregnant mice

BACKGROUND

Carbamazepine is an antiepileptic drug used widely for the treatment of epileptic seizures and neuropathic pain. Several malformations in humans, mainly neural tube defects, have been reported as a consequence of its use during pregnancy. The association between maternal use of carbamazepine and congenital eye malformations is not very well understood.

OBJECTIVE

The purpose of this study was to examine this association after intraperitoneal injection of carbamazepine during the period of organogenesis in mice.

METHODS

Balb/c timed-pregnant mice were divided into 4 experimental and control groups. Two experimental groups received daily intraperitoneal injections of 15 mg/kg (group I) or 30 mg/kg (group II) of carbamazepine on gestational days 6 to 15. Two control groups received normal saline or Tween 20 (polysorbate 20). Dams underwent Cesarean section on gestational day 18 and embryos were harvested. External examination for eye malformations, routine histological processing of malformed fetuses to study eye morphology, and skeletal staining were performed.

RESULTS

The mean weight and crown-rump of the fetuses in both experimental groups were significantly reduced compared with those of the control groups. Various malformations were detected such as brachygnathia, calvarial deformity, vertebral deformity, short tail, and brachydactyly. Premature opening of one or both eyes with mild to severe exophthalmos occurred in the 2 experimental groups. Deformed lens, retinal folds with undeveloped layers, and corneal folds with absence of surface epithelium were detected in both experimental groups.

CONCLUSIONS

This study, to the best of our knowledge, showed for the first time that intraperitoneal administration of carbamazepine at clinically comparable doses during organogenesis can induce several eye malformations in mice. The implication of these results needs to be considered when carbamazepine is administered during human pregnancy.

Ophthalmologic and neurologic findings in two children exposed to vigabatrin in utero

Vigabatrin (VGB) is an important treatment option for infantile spasms. Vigabatrin-induced visual field defects are at present the most important safety issue in the use of the drug. The knowledge concerning VGB-associated visual dysfunction in pediatric patients, particularly in those who have been exposed to VGB in utero is limited. We explored ophthalmic and neurologic findings in two children who have been exposed prenatally to VGB.

The effect of antiepileptic drugs on visual performance

Visual disturbances are a common side-effect of many antiepileptic drugs. Non-specific retino- and neurotoxic visual abnormalities, that are often reported with over-dosage and prolonged AED use, include diplopia, blurred vision and nystagmus. Some anticonvulsants are associated with specific visual problems that may be related to the mechanistic properties of the drug, and occur even when the drugs are administered within the recommended daily dose. Vigabatrin, a GABA-transaminase inhibitor, has been associated with bilateral concentric visual field loss, electrophysiological changes, central visual function deficits including reduced contrast sensitivity and abnormal colour perception, and morphological alterations of the fundus and retina. Topiramate, a drug that enhances GABAergic transmission, has been associated with cases of acute closed angle glaucoma, while tiagabine, a GABA uptake inhibitor, has been investigated for a potential GABAergic effect on the visual field. Only mild neurotoxic effects have been identified for patients treated with gabapentin, a drug designed as a cyclic analogue of GABA but exhibiting an unknown mechanism while carbamazepine, an inhibitor of voltage-dependent sodium channels, has been linked with abnormal colour perception and reduced contrast sensitivity. The following review outlines the visual disturbances associated with some of the most commonly prescribed anticonvulsants. For each drug, the ocular site of potential damage and the likely mechanism responsible for the adverse visual effects is described.

Is there an association between maternal carbamazepine use during pregnancy and eye malformations in the child?

PURPOSE

To check for an association between carbamazepine (CBZ) use by the mother during pregnancy and congenital eye malformations (i.e., anophthalmia, microphthalmia, and coloboma) in the child, as suggested by Sutcliffe et al. (1998), who reported four cases.

METHODS

We checked all the cases with these eye malformations for CBZ use by the mother in the EUROCAT Northern Netherlands dataset, which registers infants with congenital malformations and records possible teratogenic exposures (including medication taken by the mother). We also reviewed 13 studies in the literature.

RESULTS

The EUROCAT dataset recorded 77 cases of anophthalmia, microphthalmia, or coloboma, but none with prenatal exposure to CBZ. Prenatal CBZ exposure was recorded in seven other cases without congenital eye malformation. Large studies in the literature on the teratogenic effects of CBZ (and other antiepileptic drugs), including data from the MADRE database, revealed no association between these congenital eye malformations and prenatal CBZ exposure. One case reported bilateral anophthalmia and other congenital anomalies after prenatal exposure to CBZ in combination with vigabatrin and dexamethasone.

CONCLUSIONS

Our data do not support Sutcliffe's suggestion that prenatal CBZ exposure may result in congenital eye malformations. However, despite the large population represented, both the low birth prevalence of these congenital eye malformations and the low prevalence of CBZ exposure during pregnancy make it difficult to exclude an increased relative risk. The many large prospective and retrospective studies in the literature seem to agree with our findings, although there is still uncertainty about the teratogenic effect of CBZ in polytherapy.

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.

Epilepsy therapy: issues for women and men

It has been suggested that polycystic ovary syndrome is a common finding in women treated with valproate. However, in a recent study this suggestion could not be confirmed. There is currently no clear evidence that valproate contributes to the development of the polycystic ovary syndrome. Focal epileptic discharges may have an impact on the hypothalamic-pituitary-ovarian or -testicular axis. In the case of successful epilepsy surgery the impact of epilepsy on endocrine functioning may cease. This may lead to a normalization of disturbed menstrual cycles in women, and leads to a post-surgical increase of serum androgens in men. Both findings are supplemented by the results of animal experiments. Children exposed to antiepileptic drugs during pregnancy show a normal psychomotor and cognitive development. However, newly developed as well as traditional antiepileptic drugs increase the risk that a child exposed to these drugs during pregnancy will develop a malformation.