Congenital oculomotor nerve synkinesis associated with fetal retinoid syndrome

Alcohol induces neural tube defects by reducing retinoic acid signaling and promoting neural plate expansion

Introduction: Neural tube defects (NTDs) are among the most debilitating and common developmental defects in humans. The induction of NTDs has been attributed to abnormal folic acid (vitamin B9) metabolism, Wnt and BMP signaling, excess retinoic acid (RA), dietary components, environmental factors, and many others. In the present study we show that reduced RA signaling, including alcohol exposure, induces NTDs. Methods: Xenopus embryos were exposed to pharmacological RA biosynthesis inhibitors to study the induction of NTDs. Embryos were treated with DEAB, citral, or ethanol, all of which inhibit the biosynthesis of RA, or injected to overexpress Cyp26a1 to reduce RA. NTD induction was studied using neural plate and notochord markers together with morphological analysis. Expression of the neuroectodermal regulatory network and cell proliferation were analyzed to understand the morphological malformations of the neural plate. Results: Reducing RA signaling levels using retinaldehyde dehydrogenase inhibitors (ethanol, DEAB, and citral) or Cyp26a1-driven degradation efficiently induce NTDs. These NTDs can be rescued by providing precursors of RA. We mapped this RA requirement to early gastrula stages during the induction of neural plate precursors. This reduced RA signaling results in abnormal expression of neural network genes, including the neural plate stem cell maintenance genes, geminin, and foxd4l1.1. This abnormal expression of neural network genes results in increased proliferation of neural precursors giving rise to an expanded neural plate. Conclusion: We show that RA signaling is required for neural tube closure during embryogenesis. RA signaling plays a very early role in the regulation of proliferation and differentiation of the neural plate soon after the induction of neural progenitors during gastrulation. RA signaling disruption leads to the induction of NTDs through the mis regulation of the early neuroectodermal network, leading to increased proliferation resulting in the expansion of the neural plate. Ethanol exposure induces NTDs through this mechanism involving reduced RA levels.

Prenatal assessment of cerebellar vermian lobulation: fetal MRI with 3-Tesla postmortem validation

OBJECTIVES

To optimize the imaging assessment of fetal hindbrain malformations, this observational magnetic resonance imaging (MRI) study aimed to assess whether fetal vermian lobulation can be quantified accurately and whether the relative growth of vermian lobules is uniform.

METHODS

This retrospective study included singleton fetuses which underwent T2-weighted MRI in vivo with a 1.5-Tesla (T) scanner or within 24 h postmortem with a 3-T scanner between January 2007 and November 2016 at the Medical University of Vienna. We included only those showing normal structural brain development on ultrasound and MRI and which had image quality appropriate for quantitative analysis, i.e. good image quality and a precise midsagittal slice. Fetal brains were segmented and, for all discernible vermian lobules, we determined the mean relative area contribution (MRAC, the proportion of the lobule relative to the total vermian area, in terms of number of voxels). Inter- and intrarater measurement variability of a representative selection (21 cases) was determined by intraclass correlation coefficient (ICC) for voxel-based differences. A linear regression model was used to assess the correlation between the relative size of each vermian lobule (i.e. MRAC) and gestational age.

RESULTS

A total of 78 fetuses scanned in vivo aged 18-32 gestational weeks and seven fetuses scanned postmortem aged 16-30 weeks had a precise midsagittal slice and image quality sufficient for quantitative analysis. After 22 weeks of gestation, seven of the nine known vermian lobules could be discriminated reliably. The MRAC showed a mean ± SD difference of only 2.89 ± 3.01% between in-vivo and postmortem measurements. The ICC of voxel-based interrater differences was mean ± SD, 0.91 ± 0.05 and the intrarater ICC was 0.95 ± 0.03. Growth of cerebellar lobules was non-uniform: the MRAC of culmen and DFT (declive + folium + tuber) increased with gestational age, whereas that of lingula, centralis, pyramis and nodulus decreased. The growth of the uvula showed no significant correlation with gestational age.

CONCLUSIONS

Fetal vermian lobulation can be assessed accurately and reliably after 22 weeks on precise midsagittal sequences with 1.5-T T2-weighted MRI. Fetal vermian lobules show non-uniform growth, with expansion of DFT and culmen at the expense of the other vermian lobules. Evaluation and elucidation of vermian lobulation in normal fetuses should enable better characterization of fetuses with hindbrain malformations. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Effect of Oral Isotretinoin Treatment on Retinal Nerve Fiber Layer Thickness

Background:

Oral isotretinoin treatment can cause ocular side effects.

Objective:

This study was performed to detect possible toxic effects of oral isotretinoin treatment on the retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL).

Methods:

The study population consisted of 54 eyes of 27 patients with nodulocystic acne who used oral isotretinoin (Roaccutane) treatment. Macular GCL and peripapillary RNFL thickness measurements were performed using spectral domain optical coherence tomography (OCT) before and after therapy.

Results:

Before and after treatment, a complete ophthalmologic examination was normal in all eyes. However, posttreatment lower temporal (TL) values were significantly lower (76.80 ± 16.31) than pretreatment TL values (84.96 ± 24.83) ( p = .02). There was no statistically significant difference in the other OCT values, upper temporal, superotemporal, superonasal, upper nasal, lower nasal, inferonasal, and inferotemporal ( p = .35, p = .40, p = .56, p = .95, p = .94, p = .93, p = .61, respectively). Also, there was no statistically significant difference between the right and left eyes and between genders for all parameters ( p > .05).

Conclusion:

The use of oral isotretinoin treatment has increased in recent years. In addition, oral isotretinoin treatment has a broad adverse effect potential on the ocular system. The measurement of RNFL thickness, especially TL thickness, by OCT may be useful for detecting the possible toxic effect of oral isotretinoin therapy on RNFL.

Marcus Gunn jaw winking with trigemino-oculomotor synkinesis of the inferior division of the oculomotor nerve

Synkinetic aberrant innervation syndromes can involve abnormal movements of multiple extraocular and eyelid muscles. The authors describe a case of eyelid elevation associated with simultaneous adduction and depression of the eye upon chewing, sucking on a bottle, or wide opening of the mouth since birth. This represents a unique case of congenital Marcus Gunn jaw winking with trigemino-oculomotor synkinesis involving the inferior branch of the oculomotor nerve. The most likely explanation for these abnormal movements is prenatal aberrant innervation of eyelid and extraocular muscles.

A risk management program aimed at preventing fetal exposure to isotretinoin: retrospective cohort study

BACKGROUND

Preventing fetal exposure to isotretinoin is an important public health goal. Since approval of isotretinoin (1982), the Food and Drug Administration has implemented several unsuccessful risk management programs aimed at preventing fetal exposure. The Kaiser Permanente isotretinoin risk management program included electronic capture of all isotretinoin prescriptions and the documentation of pregnancy testing with each dispense.

OBJECTIVE

Our aim was to analyze the success of Kaiser Permanente's program at improving pregnancy testing rates and reducing fetal exposure.

METHODS

This was a retrospective cohort study.

RESULTS

Pregnancy testing rates improved after implementation of the Kaiser Permanente program. However, the rate of fetal exposure to isotretinoin did not change (0.21% before vs 0.23% after, P = .85). LIMITATIONS/CONCLUSION: In this study, linking a negative pregnancy test to isotretinoin dispensing did not reduce fetal exposures. Patient failure to use two contraceptive methods was the most common reason for fetal exposure. These results have important implications for iPLEDGE, the new isotretinoin risk management program mandated by the Food and Drug Administration.