Moebius syndrome: animal model--human correlations and evidence for a brainstem vascular etiology

Monozygotic twins discordant for a congenital cranial dysinnervation disorder with features of Moebius syndrome

Moebius syndrome is a congenital cranial dysinnervation disorder (CCDD) that presents with nonprogressive cranial nerve (CN) VI and VII palsies resulting in facial weakness and inability to abduct the eye(s). While many CCDDs have an underlying genetic cause, the etiology of Moebius syndrome remains unclear as most cases are sporadic. Here, we describe a pair of monochorionic, diamniotic twin girls; one with normal growth and development, and one with micrognathia, reduced facial expression, and poor feeding. Magnetic resonance imaging of the brain performed on the affected twin at 19 months of age showed severely hypoplastic or absent CN IV bilaterally, left CN VI smaller than right, and bilateral hypoplastic CN VII and IX, consistent with a diagnosis of a CCDD, most similar to that of Moebius syndrome. Genomic sequencing was performed on each twin and data was assessed for discordant variants, as well as variants in novel and CCDD-associated genes. No pathogenic, likely pathogenic, or variants of uncertain significance were identified in genes known to be associated with CCDDs or other congenital facial weakness conditions. This family provides further evidence in favor of a stochastic event as the etiology in Moebius syndrome, rather than a monogenic condition.

Exosome-shuttled miR-126 mediates ethanol-induced disruption of neural crest cell-placode cell interaction by targeting SDF1

During embryonic development, 2 populations of multipotent stem cells, cranial neural crest cells (NCCs) and epibranchial placode cells (PCs), are anatomically adjacent to each other. The coordinated migration of NCCs and PCs plays a major role in the morphogenesis of craniofacial skeletons and cranial nerves. It is known that ethanol-induced dysfunction of NCCs and PCs is a key contributor to the defects of craniofacial skeletons and cranial nerves implicated in fetal alcohol spectrum disorder (FASD). However, how ethanol disrupts the coordinated interaction between NCCs and PCs was not elucidated. To fill in this gap, we established a well-designed cell coculture system to investigate the reciprocal interaction between human NCCs (hNCCs) and human PCs (hPCs), and also monitored the migration behavior of NCCs and PCs in zebrafish embryos. We found that ethanol exposure resulted in a disruption of coordinated hNCCs-hPCs interaction, as well as in zebrafish embryos. Treating hNCCs-hPCs with exosomes derived from ethanol-exposed hNCCs (ExoEtOH) mimicked ethanol-induced impairment of hNCCs-hPCs interaction. We also observed that SDF1, a chemoattractant, was downregulated in ethanol-treated hPCs and zebrafish embryos. Meanwhile, miR-126 level in ExoEtOH was significantly higher than that in control exosomes (ExoCon). We further validated that ExoEtOH-encapsulated miR-126 from hNCCs can be transferred to hPCs to suppress SDF1 expression in hPCs. Knockdown of SDF1 replicated ethanol-induced abnormalities either in vitro or in zebrafish embryos. On the contrary, overexpression of SDF1 or inhibiting miR-126 strongly rescued ethanol-induced impairment of hNCCs-hPCs interaction and developmental defects.

Poland-Möbius syndrome: a case report implicating a novel mutation of the PLXND1 gene and literature review

BACKGROUND

Möbius (Moebius) and Poland's syndromes are two rare congenital syndromes characterized by non-progressive bilateral (and often asymmetric) dysfunction of the 6^th and 7^th cranial nerves and hypoplasia of the pectoral muscles associated with chest wall and upper limb anomalies respectively. Manifest simultaneously as Poland-Möbius (Poland-Moebius) syndrome, debate continues as to whether this is a distinct nosological entity or represents phenotypic variation as part of a spectrum of disorders of rhomboencephalic development. Etiological hypotheses implicate both genetic and environmental factors. The PLXND1 gene codes for a protein expressed in the fetal central nervous system and vascular endothelium and is thus involved in embryonic neurogenesis and vasculogenesis. It is located at chromosome region 3q21-q22, a locus of interest for Möbius syndrome.

CASE PRESENTATION

We present the first report of a patient with Poland-Möbius syndrome and a mutation in the PLXND1 gene. A child with Poland-Möbius syndrome and a maternally inherited missense variant (NM_015103.2:ex14:c.2890G > Ap.V964M) in the PLXND1 gene is described. In order to contextualize these findings, the literature was examined to identify other confirmed cases of Poland-Möbius syndrome for which genetic data were available. Fourteen additional cases of Poland-Möbius syndrome with genetic studies are described in the literature. None implicated the PLXND1 gene which has previously been implicated in isolated Möbius syndrome.

CONCLUSIONS

This report provides further evidence in support of a role for PLXND1 mutations in Möbius syndrome and reasserts the nosological link between Möbius and Poland's syndromes.

LEVEL OF EVIDENCE

Level V, Descriptive Study.

Effect of transient maternal hypotension on apoptotic cell death in foetal rat brain

BACKGROUND

Intrauterine perfusion insufficiency induced by transient maternal hypotension has been reported to be associated with foetal brain malformations. However, the effects of maternal hypotension on apoptotic processes in the foetal brain have not been investigated experimentally during the intrauterine period.

AIMS

The aim of this study was to investigate the effects of transient maternal hypotension on apoptotic cell death in the intrauterine foetal brain.

STUDY DESIGN

Animal experimentation.

METHODS

Three-month-old female Wistar albino rats were allocated into four groups (n=5 each). The impact of hypoxic/ischemic injury induced by transient maternal hypotension on the 15th day of pregnancy (late gestation) in rats was investigated at 48 (H17 group) or 96 hours (H19 group) after the insult. Control groups underwent the same procedure except for induction of hypotension (C17 and H17 groups). Brain sections of one randomly selected foetus from each pregnant rat were histopathologically evaluated for hypoxic/ischemic injury in the metencephalon, diencephalon, and telencephalon by terminal transferase-mediated dUTP nick end labelling and active cysteine-dependent aspartate-directed protease-3 (caspase-3) positivity for cell death.

RESULTS

The number of terminal transferase-mediated dUTP nick end labelling (+) cells in all the areas examined was comparable in both hypotension and control groups. The H17 group had active caspase-3 (+) cells in the metencephalon and telencephalon, sparing diencephalon, whereas the C19 and H19 groups had active caspase-3 (+) cells in all three regions. The number of active caspase-3 (+) cells in the telencephalon in the H19 group was higher compared with the metencephalon and diencephalon and compared with H17 group (p<0.05).

CONCLUSION

Our results suggest that prenatal hypoxic/ischemic injury triggers apoptotic mechanisms. Therefore, blockade of apoptotic pathways, considering the time pattern of the insult, may constitute a potential neuroprotective approach for the detrimental effects of prenatal hypoperfusion.

Oral motor assessment in individuals with Moebius syndrome

BACKGROUND

Moebius syndrome (MS) is a rare congenital condition that is characterised by facial hypomimia and congenital strabismus caused by complete or partial impairment of the 6th and 7th cranial nerves. MS may be further associated with other nerves or malformations, mainly involving the extremities. The objective of this study was to quantify the decrease in oral motor performance in people with MS compared with normoreactive individuals using the Oral Motor Assessment Scale (OMAS).

METHODS

The study group comprised 33 subjects between the ages of 2 and 20 years (average age: 10 ± 5 years) with MS along with 46 age- and gender-matched control subjects.

RESULTS

The study group displayed a lower average functional score than the control group (P < 0.0001). A significant lack of lip closure (P = 0.03) and anterior lingual seal during swallowing (P = 0.03) occurred in the study group; in most cases, the individuals with MS were classified as 'subfunctional'. In addition, individuals with MS in the older age group displayed better functional scores than those in the younger group (P = 0.05).

CONCLUSIONS

Functional damage to oral motor function in individuals with MS is evident, but differs among patients with respect to severity and the movements that are compromised. However, overall, improvements in the functional patterns of these individuals can be observed as they mature in age.

Mid-gestation pregnancy is not disrupted by a 5-day gastrointestinal mucosal cytoprotectant oral regimen of misoprostol

REASONS FOR PERFORMING STUDY

To investigate effects of a 5-day oral misoprostol regimen recommended for use in horses as a gastrointestinal mucosal cytoprotectant during colic on mid-gestation pregnancies.

OBJECTIVES

To monitor cervical tone, ultrasonographic characteristics of the uterus, cervix and conceptus, as well as serum progesterone and oestrone sulphate concentrations, and observations of general health, behaviour and comfort of mid-gestation mares given a 5-day course of misoprostol or control treatment.

METHODS

Eleven light horse and pony mares with known breeding dates were administered 5 µg/kg bwt misoprostol orally, twice daily for 5 days. General health and pregnancy status were monitored daily during treatment via general physical examination, as well as palpation and ultrasonography per rectum of the uterus, cervix and conceptus. Jugular serum was obtained during and for 5 days following treatment for assay of progesterone and oestrone sulphate concentrations. Additionally, daily 12 h video samples of the mares were obtained to evaluate behaviour and comfort.

RESULTS

All findings, including cervical tone, ultrasonographic characteristics of the uterus, cervix and conceptus, as well as progesterone and oestrone sulphate concentrations, and observations of general health, behaviour and comfort, were similar during misoprostol and control treatment.

CONCLUSIONS

Treatment of pregnant mares with a gastrointestinal mucosal cytoprotectant regimen of oral misoprostol for 5 days did not disrupt pregnancy, nor adversely affect the general health and comfort of these mares. Additional investigation of treatment at earlier and later stages of gestation, for longer-term treatment, as well as evaluating neonates for developmental disturbances, would add further information on safety of misoprostol during gestation.

POTENTIAL RELEVANCE

These results provide some assurance of safety of a 5-day gastrointestinal mucosal cytopretectant regimen of oral misprostol in mid-gestation pregnant mares.

Möbius sequence in a girl and arthrogryposis in her half-brother: distinct phenotypes caused by prenatal injuries

Möbius sequence is a congenital facial and abducens nerve palsy, frequently associated to abnormalities of extremities. Arthrogryposis multiplex congenital is defined as a congenital fixation of multiple joints seldom of neurogenic origin. Both sequences must have a genetic origin, but usually are sporadic cases related to environmental factors such as drugs exposition and maternal trauma. A 5-year-old girl and a 1-year-old boy were born with Möbius sequence and arthrogryposis multiplex congenital, respectively. During pregnancies, the mother had vaginal bleeding at 7 weeks and used crack (free-based cocaine) in the first trimester, respectively. The girl also has equinovarus talipes and autistic behavior. The boy has arthrogryposis with flexion contractures of the feet and knees. A vascular disruption, due to hemorrhage and cocaine exposure, causing a transient ischemic insult to embryos in a critical period of development may be responsible for distinct phenotypes in these cases.

Moebius sequence and autism spectrum disorders--less frequently associated than formerly thought

Moebius sequence is a rare congenital disorder usually defined as a combination of facial weakness with impairment of ocular abduction. It is questionable, whether there is a strong association of the sequence with autism spectrum disorders (ASDs) as suggested in some earlier case reports and studies. Twenty-two participants with Möbius sequence aged 6-16 years followed a request of the German Moebius foundation to participate in a nationwide study. All patients had a physical examination and intelligence testing. Primary caregivers were asked to complete two screening measures of ASD (Behaviour and Communication Questionnaire, VSK; Marburger Asperger's Syndrome Rating Scale, MBAS). For those who reached the cut-off for ASD and/or showed behavioural aspects indicative of ASDs during IQ testing and/or physical examination, well standardized diagnostic instruments (Autism Diagnostic Interview-Revised, Autism Diagnostic Observation Schedule, and Kinder-DIPS) were administered. Minimal diagnostic criteria for Möbius sequence were congenital facial weakness (uni- or bilateral) and impairment of ocular abduction (uni- or bilateral). Three boys (one of them mentally retarded) out of 22 participants (12 males and 10 females) were found suspicious of ASD by screening, but none of them fulfilled diagnostic criteria of ASD on a clinical consensus conference. Therefore, ASDs seem to be not as frequent as reported in previous studies on patients with Möbius sequence.

Thalidomide and misoprostol: Ophthalmologic manifestations and associations both expected and unexpected

Thalidomide is a very potent teratogen capable of causing severe systemic malformations if the fetus is exposed during the sensitive period. Although structural anomalies of the eye can occur from thalidomide exposure, the most frequent eye complication is secondary to damage to the cranial nuclei in the brain stem, resulting in aberrant neurologic connections causing a condition of abnormal ocular movement, Duane syndrome. A less frequent anomalous neurologic complication is tearing when eating (paradoxical gustolacrimal tearing or "crocodile tears") or lack of emotional tearing. The involvement of the 6th and 7th cranial nerves, often seen together in the thalidomide-affected individual, is also characteristic of Möbius syndrome/sequence. This syndrome usually occurs sporadically, but characteristic findings of this condition have also been observed in South American children who were born after an unsuccessful attempt to induce abortion with the prostaglandin drug misoprostol (Cytotec). Aberrant tearing also occurs in some individuals with Möbius syndrome. Autism spectrum disorder (ASD), an unexpected associated finding in a Swedish thalidomide study, is now also noted in Möbius studies, in patients both with and without exposure to misoprostol.

Autism spectrum disorders in children and adolescents with Moebius sequence

Moebius sequence is a rare congenital disorder usually defined as a combination of facial weakness with impairment of ocular abduction. A strong association of Moebius sequence with autism spectrum disorders (ASDs) has been suggested in earlier studies with heterogenous age groups. The primary caregivers of all children and adolescents with Moebius sequence aged 6-17 years known to the German Moebius foundation were anonymously asked to complete two screening measures of ASD [Behavior and Communication Questionnaire (VSK); Marburger Asperger's Syndrome Rating Scale (MBAS)]. For those who reached the cut-off for ASD, well standardized diagnostic instruments (Autism Diagnostic Interview-Revised, Autism Diagnostic Observation Schedule, WISC-III, and Kinder-DIPS) should be administered. Minimal diagnostic criteria for Moebius sequence were congenital facial weakness (uni- or bilateral) and impairment of ocular abduction (uni- or bilateral). Familiar cases should be excluded. The primary caregivers of 35/46 children and adolescents (18 males, 17 females, mean age 11.5 years) sent back completed questionnaires, but only 27 subjects met inclusion criteria. According to the primary caregivers, none of these subjects showed mental retardation. Two probands (both males 9 and 16 years old) reached the cut-off of the MBAS whereas the results of the VSK did not indicate ASDs in any of the patients. The 9 year old boy could be examined personally and did not meet diagnostic criteria of ASD. ASDs might be not as frequent as reported in previous studies on patients with Moebius sequence, at least not in patients without mental retardation.

Delineation of a multiple congenital abnormality syndrome in the offspring of pregnant women affected with high fever-related disorders: a population-based study

Our previous study showed an association between high fever-related maternal diseases during the second and/or third gestational months and a higher risk of multiple congenital abnormalities (MCA) in the population-based large dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities. The objective of our analysis is to attempt the delineation of the spectrum of the characteristic component defects of an MCA syndrome associated with high fever-related maternal diseases. Of 1349 cases with MCA without recognized genetic and teratogenic syndromes in the total dataset, 181 had a possible association with influenza, common cold with secondary complications, tonsillitis and recurrent orofacial herpes with high fever in the second and/or third gestational months. At the evaluation of component defects in these 181 MCA cases, an association was found between the components of the so-called two schisis-type defects, such as neural-tube defects and orofacial cleft, in addition to microphthalmos, neurogenic limb contractures, and indeterminate sex (i.e. maldevelopment of male external genital organs, such as hypoplasia of the penis and pseudohermaphroditism). In addition, previous findings that showed an association between high fever and facial anomalies (micrognathia and midfacial hypoplasia), microcephaly and defects of external ears, were confirmed in our dataset. Thus, we delineated the maternal high fever-related MCA syndrome, including the above component defects and this MCA syndrome was identified in 38 MCA (21.0%) among 181 MCA babies born to mothers with high fever-related diseases. In the total dataset of 1349 MCA, 2.8% of cases can be associated with high fever.

[Congenital cranial dysinnervation disorders]

Congenital cranial dysinnervation disorders (CCDDs) are responsible for 1-2% of infant strabismus cases. Insufficient innervation and misinnervation of aberrant nerve fibres lead to motility restrictions and synkinesis. We present the most common CCDDs and explain their pathogenesis and the resulting clinical features. Furthermore, we emphasize essential diagnostic steps and treatment aspects.

The effect of hypoxia in development

There is increasing evidence that the oxygen supply to the human embryo in the first trimester is tightly controlled, suggesting that too much oxygen may interfere with development. The use of hypoxia probes in mammalian embryos during the organogenic period indicates that the embryo is normally in a state of partial hypoxia, and this may be essential to control cardiovascular development, perhaps under the control of hypoxia-inducible factor (HIF). A consequence of this state of partial hypoxia is that disturbances in the oxygen supply can more easily lead to a damaging degree of hypoxia. Experimental mammalian embryos show a surprising degree of resilience to hypoxia, with many organogenic stage embryos able to survive 30-60 min of anoxia. However, in some embryos this degree of hypoxia causes abnormal development, particularly transverse limb reduction defects. These abnormalities are preceded by hemorrhage/edema and tissue necrosis. Other parts of the embryo are also susceptible to this hypoxia-induced damage and include the genital tubercle, the developing nose, the tail, and the central nervous system. Other frequently observed defects in animal models of prenatal hypoxia include cleft lip, maxillary hypoplasia, and heart defects. Animal studies indicate that hypoxic episodes in the first trimester of human pregnancy could occur by temporary constriction of the uterine arteries. This could be a consequence of exposure to cocaine, misoprostol, or severe shock, and there is evidence that these exposures have resulted in hypoxia-related malformations in the human. Exposure to drugs that block the potassium current (IKr) can cause severe slowing and arrhythmia of the mammalian embryonic heart and consequently hypoxia in the embryo. These drugs are highly teratogenic in experimental animals. There is evidence that drugs with IKr blockade as a side effect, for example phenytoin, may cause birth defects in the human by causing periods of embryonic hypoxia. The strongest evidence of hypoxia causing birth defects in the human comes from studies of fetuses lacking hemoglobin (Hb) F. These fetuses are thought to be hypoxic from about the middle of the first trimester and show a range of birth defects, particularly transverse limb reduction defects.

Neuropsychiatric findings of Möbius sequence -- a review

Möbius sequence is a rare condition of heterogeneous, and in most cases, unclear; origin, usually defined as a unilateral or bilateral congenital facial weakness with impairment of ocular abduction, which is frequently associated with limb anomalies. Disturbances in psychomotor and speech development are very common, and mental retardation is estimated to occur in 10-15% of cases. The incidence of autistic spectrum disorders might be increased in patients with Möbius sequence. After a brief overview on aetiology and physical appearance, current knowledge of cognitive capacities and academic achievement; psychomotor development; development of speech, language and communication; behaviour problems; psychiatric comorbidity and possible therapeutic interventions are reviewed.

Mitochondrial dysmorphology in the neuroepithelium of rat embryos following a single dose of maternal hyperthermia during gestation

Hyperthermia is teratogenic to human and animal embryos and induces mainly anomalies of the nervous system. However, the teratogenic mechanism is poorly understood. Mammalian embryos are known to switch from anaerobic to aerobic metabolism around the time of neural tube closure. This critical event might be sensitive to hyperthermia. The objective of the present study was to evaluate the ultrastructural changes of the mitochondria of the neuroepithelium (NE) of rat embryos following maternal exposure to hyperthermia. Pregnant rats were heat stressed for an hour on gestation day (GD) 9 and embryos were examined by electron microscopy on GD 10. NE presented extensive apoptosis. Intercellular junctions were weakened and copious cellular debris projected into the ventricle. The mitochondria were of diverse size and shape. Most of them were swollen and had short cristae and electron dense matrix. Hydropic changes were also observed in numerous mitochondria. Lipid-laden mitochondria were found in the apical portions of neuroblasts. The mesenchyme (ME) of heat-treated embryos showed paucity of cells and only as frequent apoptosis as the controls. Their mitochondria also showed changes similar to those of the NE. Additionally extensive lipid accumulation was observed in and in the vicinity of mitochondria, often surrounded by short strands of endoplasmic reticulum. Whereas mitochondrial pathology was associated with profound apoptosis in the NE, growth restriction and lipid accumulation accompanied mitochondrial changes in the ME. The results of this study indicate that the embryonic response to maternal heat shock is tissue-specific and morphologically distinct in this species.

Marshall J. Edwards: Discoverer of maternal hyperthermia as a human teratogen

In a series of animal studies performed over a career spanning 40 years at the University of Sydney, Professor Marshall J. Edwards investigated the hypothesis that maternal hyperthermia during gestation can be teratogenic to the developing fetus. He is one of few investigators to have discovered a known human teratogen primarily through animal studies. In 1970 he earned his Ph.D. from the University of Sydney, writing a doctoral thesis entitled "A Study of Some Factors Affecting Fertility of Animals with Particular Reference to the Effects of Hyperthermia on Gestation and Prenatal Development of the Guinea-Pig." He went on to prove that hyperthermia-induced malformations in animals involve many organs and structures, particularly the central nervous system. Other defects include craniofacial anomalies, heart defects and hypodactyly, cataracts and coloboma, kyphoscoliosis, renal anomalies, dental agenesis, and abdominal wall defects. In a series of carefully planned and executed experiments, he demonstrated that the type of defect is related to the timing of the hyperthermic insult, and analyzed the underlying mechanisms. Cell death, membrane disruption, vascular disruption, and placental infarction were all implicated in causing embryonic damage. This special article reviews the scientific discoveries and personal philosophy of Marshall J. Edwards, the discoverer of maternal hyperthermia as a human teratogen.

The spectrum of Möbius syndrome: an electrophysiological study

We studied the nature and extent of facial muscle innervation and the involvement of the motor and sensory long tracts in Möbius syndrome, in order to shed light on the pathophysiological mechanism of the syndrome. Standardized blink reflexes, direct responses of the facial nerves to the orbicularis oculi muscles and concentric needle electrode electromyography in orbicularis oculi and/or oris muscles were measured in 11 patients with Möbius syndrome, of whom six participated in MRI studies, all showing absent facial nerves. We performed motor- and somatosensory-evoked potentials in seven Möbius patients. We demonstrated three distinct patterns of abnormalities suggesting different sites of the primary lesion in different patients. (i) Presence of normal blink reflexes and facial compound motor action potentials, normal habituation tests, a reduced recruitment in the facial muscles and an aberrant 'blink reflex-like' response of the orbicularis oculi muscle upon stimulation of the facial nerve region, which suggests a supranuclear origin of the defect. (ii) Absent blink reflexes, absent direct responses of the facial nerves and absent motor activity on needle electromyography, indicating a defect at the facial nuclear level. However, the nuclear defect might mask an additional supranuclear defect, which cannot, therefore, be excluded in these patients. (iii) A disperse pattern of facial compound action potentials combined with long latencies that were recorded with concentric needle electrodes, indicating involvement of motor axons in the facial nerve, possibly secondary to nuclear involvement. An additional supranuclear defect cannot be excluded in these cases. All evoked potentials studied were normal. The electrophysiological findings of the facial muscles show a spectrum of disturbances varying in degree of severity and diverse in the extent of structures involved, in 11 Möbius patients. At one end of the spectrum are patients with completely immobile faces in whom electrophysiological testing shows no signs of involvement of the facial nuclei, nerves or muscles, suggestive of a dysfunction at the supranuclear level. At the other extreme of the spectrum are patients with complete absence of responses upon facial nerve stimulation and absence of motor unit activity. This is at least indicative of a defect at the facial nuclear level. While a supranuclear defect is compatible with the concept that Möbius syndrome is a developmental disorder of the lower brainstem, intact facial nuclei as part of the syndrome has not been suggested before. The findings corroborate the concept of the Möbius syndrome being a complex regional developmental disorder of the brainstem.

Möbius sequence, Robin complex, and hypotonia: severe expression of brainstem disruption spectrum versus Carey-Fineman-Ziter syndrome

We report on nine unrelated children fitting a diagnosis of Carey-Fineman-Ziter syndrome (CFZS). All children presented with Möbius sequence, Pierre Robin complex (6/9) or micrognathia, and hypotonia. Some had primary hypoventilation, delayed development, and acral anomalies. The neuropathological investigations performed in two patients showed a combination of dysplastic lesions (neuronal heterotopias) and encephaloclastic changes consisting of small foci of necrosis with microcalcifications. The mother of a third child had severe trauma during her 2nd month of pregnancy. Based on a review of the literature on MS and CFZS, we suggest designating as "Robin-Möbius phenotype" a distinct clinical variant of MS with extensive brainstem involvement, Robin complex, hypotonia without specific muscle disorder, clubfeet and variable acral anomalies. This condition appears to bear a higher risk of mental handicap and perhaps a higher recurrence risk than "common" MS. Neuropathology and neuroimaging are suggestive, at least in some cases, of a vascular disruption, which could be exogenous, or secondary to a genetic predisposition. Etiologic heterogeneity seems likely and, in that respect, the original CFZS family could represent a private syndrome fitting on the "Robin-Möbius" spectrum. Despite the existence of two familial reports, recurrence risk is probably much lower than 25%, although exact figures cannot be extracted from the available literature.

Autism associated with conditions characterized by developmental errors in early embryogenesis: a mini review

Autism is a complex developmental disorder without an established single etiology but with significant contributions from genetic studies, functional research, and neuropsychiatric and neuroradiologic investigations. The purpose of this paper is to review the findings in five studies involving individuals manifesting the characteristic findings of autism spectrum disorder associated with malformations and dysfunctions known to result from early embryogenic defects. These investigations include two associated with teratogens (thalidomide embryopathy, Mobius sequence with misoprostol) and three (most Mobius sequence cases, CHARGE association, Goldenhar syndrome) with no known etiology. These studies suggest that early embryonic development errors often involving cranial nerve palsies, internal and external ear malformations, ophthalmologic anomalies, and a variety of systemic malformations may be associated with autism spectrum disorders statistically more frequently than expected in a normal population. Although the exact time of developmental insult for each condition cannot be identified, the evidence is that it may occur as early as week 4 to 6+ of embryogenesis.

Brainstem calcification in Möbius syndrome

Möbius syndrome is characterized by congenital facial diplegia, and may be associated with limb or orofacial malformations. A number of mechanisms have been proposed to explain the pathogenesis, including prenatal ischemia. We identified seven children with Möbius syndrome over the 10-year interval 1992-2001, all of whom manifested incomplete bilateral facial palsy. Associated limb and orofacial anomalies were observed in six cases. Computed tomographic scans were available in six children, and five of them manifested brainstem calcification which was most prominent in the floor of the fourth ventricle. The calcification was detected as early as 7 days of age and did not change with time, suggesting a static condition of prenatal onset. These observations support the hypothesis that the pathology in Möbius syndrome is secondary to prenatal brain ischemia.

Möbius sequence in children exposed in utero to misoprostol: Neuropathological study of three cases

BACKGROUND

Misoprostol exposure in the first trimester of pregnancy has been related to congenital malformations, particularly the Möbius sequence and terminal transverse limb defects.

CASES

Neuropathological findings of three patients with Möbius sequence related to misoprostol are reported. No previous pathological studies have shown these abnormalities to be associated with misoprostol exposure in utero. The brain stem was cut serially, from the rostral mesencephalum to the caudal aspect of the medulla, and all fragments were stained with hematoxylin-eosin and cresyl violet. Old ischemic-anoxic foci of gliosis, with necrosis and calcification, dorsally situated, were present from the pons to the medulla, involving some cranial nerve nuclei (especially the IV, VII, and XII) that were partially or completely depopulated of neural cells.

CONCLUSIONS

The findings suggest a circulatory mechanism to the Möbius sequence, with vascular disruption involving the territory of the subclavian artery, occurring in a critical period of embryonic life between six to eight weeks postconception. These cases add further evidence of the role of misoprostol as a teratogen.

Möbius and Möbius-like patients: etiology, diagnosis, and treatment options

The surgical goal in Mobius patients is far more modest and differs from patients with unilateral developmental facial paralysis. It is impossible to restore a true smile in these mask-like, expressionless faces. Despite sophisticated microneurovascular transplantations, movement can only be restored along one vector and enhanced firmness in the cheeks, thus multiple differentiated facial animation is not achievable. A detailed neurological evaluation can identify possible motor donors or residual function, which can be used for additional dynamic restorations. Due to the multiple cranial nerve involvement a thorough clinical and electrophysiological examination is mandatory. In addition, electromyographic survey of the potential motor donors is very helpful to avoid weak wasted regeneration and prevent further downgrading of function. Because of the variety of cranial nerves involved in Möbius' syndrome, a standard procedure for dynamic restoration cannot and should not be promoted; instead, a careful preoperative objective and quantitative assessment should guide the reconstructive surgeon to the optimal reconstruction strategy. Useful movement can be restored in afflicted patients that may signal physical and psychological rehabilitation.

Multiple congenital contractures: birth prevalence, etiology, and outcome

OBJECTIVES

We wanted to estimate the birth prevalence of multiple congenital contractures (MCC), determine the cause of the MCC according to the primary level of involvement of the developing motor system, and compare the different groups in terms of inheritance, mortality, and morbidity.

STUDY DESIGN

A retrospective epidemiologic study through the screening of registers, reviews of medical records, and clinical re-examinations was performed in western Sweden to identify all the children with MCC born between 1979 and 1994.

RESULTS

The birth prevalence of MCC on the basis of 68 cases was 1 in 5100 live births. The majority of cases with cerebral involvement (n = 23), spinal involvement (n = 16), or mechanical restriction (n = 3) were sporadic, whereas most cases with neuromuscular (n = 12) or connective tissue involvement (n = 9) were inherited. The cerebral group was more severely affected compared with the other groups in terms of mortality, joint contractures at birth, feeding difficulties during infancy, and independent walking at follow-up. In 8 cases with myopathy, the joint contractures were normalized on follow-up.

CONCLUSION

A search for a specific etiology in each case is important for genetic counseling, prognosis, and therapy because inheritance, mortality, and morbidity differ between the groups.

Development of speech, feeding, eating, and facial expression in Möbius sequence

OBJECTIVE

Möbius sequence is a rare congenital disorder with the primary diagnostic criteria of congenital facial and abducens nerve palsy. Involvement from other cranial nerves is common. Orofacial anomalies and limb malformations may be associated with the disorder. Mental retardation and autism have been reported in some. The aim of this study was to describe orofacial dysfunction observed in a prospective, multidisciplinary study of individuals with Möbius sequence.

METHODS

Twenty-five patients with Möbius sequence, aged 2 months to 54 years, participated in the study. Clinical observations by different medical specialists were collected in an established database. Dentists and a speech pathologist made the orofacial examination. The parents or the patient described orofacial function and dysfunction through interviews and a questionnaire.

RESULTS

Bilateral facial palsy was observed in 16 patients, unilateral palsy in 9. Observed orofacial anomalies were tongue dysfunction (16), micrognatia (8), microglossia (7), cleft palate (4), and cleft lip (1). Seventeen had speech problems, 16 reported feeding difficulties in infancy, 14 eating problems, and 8 drooling.

CONCLUSIONS

Orofacial problems are common in Möbius sequence and have a significant impact on the quality of life for the patient and for the whole family. Early intervention by a speech pathologist and a paediatric dentist should be undertaken to improve orofacial function and symptoms. Plastic surgery, oral motor training, facial massage, speech therapy, and orthodontic treatment are some of the therapy methods that can be considered.

High maternal fever during gestation and severe congenital limb disruptions

Hyperthermia is defined as a temperature of at least 1.5 degrees C over the normal core body temperature. It is a proven teratogen in animals and in humans. The type of defects induced by hyperthermia in experimental animals are: anencephaly/exencephaly, encephalocele, microphthalmia, arthrogryposis, abdominal wall defects, limb deficiencies, embryonic death, and resorption. In humans it has been observed that infants prenatally exposed to hyperthermia presented with spina bifida, encephalocele, microphthalmia, micrognathia, external ear anomalies, cardiac defects, hypospadias, gastrointestinal defects, cleft lip and/or cleft palate, abdominal wall defects, diaphragmatic hernia, Hirschsprung disease, Möbius syndrome, oromandibular-limb hypogenesis spectrum, and spontaneous abortions. We describe an additional case with severe limb deficiencies whose mother had fever over 39 degrees C for 2 days in the second and in the fourth month of amenorrhoea. We conclude that, based on the degree of development of the humeri and the femora and the type of limb deficiencies, this case presents a disruption that most probably occurred in the fourth month of gestation.

The möbius sequence: a relook

BACKGROUND

The constellations of findings often referred to as Mobius syndrome might be better described as Mobius sequence, because the term sequence defines a cascade of secondary events after an embryonic insult from heterogeneous causes. Classic clinical findings include evidence of sixth and seventh cranial nerve involvement, often with associated malformations of limbs, craniofacial structures, and other cranial nerves.

METHODS

A prospective study was undertaken in Sweden of 25 patients who showed characteristic findings of Mobius sequence.

RESULTS

Of the patients who did not have strabismus surgery, 10 patients had straight eyes in the primary position, 7 had esotropia, 2 had exotropia, and 1 had hypertropia. All had significant limitation of abduction, except 1 patient with exotropia who showed minimal underaction on abduction but a large limitation of adduction. In the description in these early cases, some patients manifested a clinical pattern resembling a horizontal gaze paresis. Narrowing of the palpebral fissure on adduction similar to that seen in Duane syndrome was observed in a few cases. Two patients had ptosis. Nineteen patients had diminished facial expression bilaterally, often asymmetric, and 6 cases appeared to be unilateral. Seven patients had abnormal tearing. Associated systemic findings included Poland anomaly (2), club feet or other limb anomalies (8), micrognathia (8), tongue malformations (17), cleft palate (5), and speech problems (18). An unusual finding was autism syndrome (6) or autism-like syndrome (1).

CONCLUSIONS

The associated findings in Mobius sequence may give further clues to the location and timing of the developmental disturbance. The wide range of ocular motility patterns suggests that the previous concept of a lesion solely in the sixth nerve nucleus is an inadequate explanation for these findings.

Surgical management of ocular motor cranial nerve palsies

This article reviews the various surgical treatment approaches currently used in the management of ocular motor cranial nerve palsies. Regardless of the approach, the final goal is improved alignment, especially in the primary and reading positions.

Genetic factors in human sleep disorders with special reference to Norrie disease, Prader-Willi syndrome and Moebius syndrome

Sleep-wake problems are common in specific inborn errors of metabolism and structure of the central nervous system. Psychological factors, behavioural difficulties, metabolic disturbances, and widespread rather than focal damage to the nervous system are present in many of these diseases and all influence the sleep-wake cycle. However, a number of conditions cause relatively focal damage to the neuroanatomical substrate of sleeping and waking. These include fatal familial insomnia, with involvement of the prion protein gene on chromosome 20, Norrie disease, the Prader-Willi syndrome and the Moebius syndrome. The last three important conditions, although rare, are considered in detail in this review. They result in sensory deprivation, hypothalamic and mid-brain damage, and involve the X-chromosome, chromosome 15, and chromosome 13, respectively. These conditions cause a wide variety of sleep disturbance, including parasomnias, daytime sleepiness, and a condition like cataplexy. The place of the relevant gene products in normal sleep regulation needs further exploration.

Teratogen update: gestational effects of maternal hyperthermia due to febrile illnesses and resultant patterns of defects in humans

This review has covered the pertinent literature concerning the teratogenic effects of hyperthermia in man and experimental animals. This is the first teratogen that was initially discovered in animals and then subsequently found to be a cause for concern in humans when similar patterns of defects were observed. Hyperthermia is a physical agent with a dose-response curve for abortions and malformations, but these effects can be mitigated in some circumstances by the heat shock response (HSR). We have reviewed the known functions of HSR and provided some insight into why embryos have some protection following an initial dose of heat, if it is sufficient to initiate the response. Thus, by reviewing the effects of hyperthermia in experimental animals, as well as malformative and protective mechanisms of teratogenesis, we have attempted to understand the effects of human hyperthermia teratogenesis.

Möbius' syndrome: features and etiology

PURPOSE

To review the clinical features and possible aetiology of all cases of Möbius' syndrome presented at the Royal Alexandra Hospital for Children in Sydney, Australia, from 1963 through 1995.

METHODS

All charts of patients suffering from Möbius' syndrome were reviewed, and each patient was thoroughly assessed by a geneticist and a pediatric ophthalmologist.

RESULTS

Patterns of systemic and ocular clinical features became evident. Of 23 patients in the series, 10 (43%) had a history significant events in utero.

CONCLUSIONS

All patients suffering from Möbius' syndrome require thorough assessment by a multidisciplinary team including a geneticist or pediatrician and a pediatric ophthalmologist. Significant vascular events of pregnancy may explain some cases of fetal vascular disruption to the brainstem.

Neuropathological findings in Moebius syndrome

Pathological findings in two patients with Moebius syndrome and lethal fetal akinesia sequence are described. In both patients a congenital brain stem malformation with neuronal loss in the cranial nerve nuclei and tegmental microcalcifications was observed. In one patient, the association with splenogonadal fusion was observed, whilst in the second patient, the association with tetraperomelia was present. As the association of peromelia and splenogonadal fusion is a well-known association, the different combination of splenogonadal fusion, peromelia and Moebius syndrome due to congenital brain stem anomalies with necrosis might be the result of a disruptive phenomenon during a prolonged vulnerable critical period in the 5th and 6th week of embryonic life. The finding of olivary dysplasia in one case, reminiscent of olivary dysplasia in Zellweger syndrome and in Miller Dieker syndrome, might suggest a primary malformation underlying Moebius syndrome due to brain stem defects.

Use of misoprostol during pregnancy and Möbius' syndrome in infants

BACKGROUND

Patients with upper gastrointestinal ulceration may be treated with misoprostol, but it is not recommended for pregnant women because it may stimulate uterine contractions and cause vaginal bleeding and miscarriage. Recent data from Brazil, where misoprostol is used orally and vaginally as an abortifacient, have suggested a relation between the use of misoprostol by women in an unsuccessful attempt to terminate pregnancy and Möbius' syndrome (congenital facial paralysis) in their infants.

METHODS

We compared the frequency of misoprostol use during the first trimester by mothers of infants in whom Möbius' syndrome was diagnosed and mothers of infants with neural-tube defects in Brazil. All diagnoses in infants were made between January 16, 1990, and May 31, 1996, by clinical geneticists at seven hospitals who also interviewed the mothers and recorded information about the administration of misoprostol, among other data.

RESULTS

We identified 96 infants with Möbius' syndrome and matched them with 96 infants with neural-tube defects. The mean age at the time of the diagnosis of Möbius' syndrome was 16 months (range, 0.5 to 78), and the diagnosis of neural-tube defects was made within 1 week of birth in most cases. Among the mothers of the 96 infants with Möbius' syndrome, 47 (49 percent) had used misoprostol in the first trimester of pregnancy, as compared with 3 (3 percent) of the mothers of the 96 infants with neural-tube defects (odds ratio, 29.7; 95 percent confidence interval, 11.6 to 76.0). Twenty of the mothers of the infants with Möbius' syndrome had taken misoprostol only orally (odds ratio, 38.8; 95 percent confidence interval, 9.5 to 159.4), 20 had taken misoprostol both orally and vaginally, 3 had taken the drug vaginally, and 4 did not report how they took the drug.

CONCLUSIONS

Attempted abortion with misoprostol is associated with an increased risk of Möbius' syndrome in infants.

Congenital abnormalities in Brazilian children associated with misoprostol misuse in first trimester of pregnancy

BACKGROUND

Misoprostol is commonly used to induce abortion in Brazil, and in other countries in South and Central America where abortions are illegal. However, misoprostol is not very effective in inducing abortions, and exposure to the drug in utero can cause abnormalities in the fetus. We aimed to define the common phenotypical effects of exposure to the drug.

METHODS

We studied 42 infants from São Paulo, Brazil, who were exposed to misoprostol during the first 3 months of gestation, and then born with congenital abnormalities. We interviewed each of the infants' mothers to find out about misoprostol exposure and dosage. Each infant was physically examined by a geneticist or a neuropaediatrician.

FINDINGS

17 of the infants had equinovarus with cranial-nerve defects. Ten children had equinovarus as part of more extensive arthrogryposis. The most distinctive phenotypes were arthrogryposis confined to the legs (five cases) and terminal transverse-limb defects (nine cases) with or without Mobius sequence. The most common dose of misoprostol taken was 800 microg (range 200-16000 microg).

INTERPRETATION

Deformities attributed to vascular disruption were found in these children. We suggest that the uterine contractions induced by misoprostol cause vascular disruption in the fetus, including brain-stem ischaemia. Information on the effects of taking misoprostol during pregnancy should be made more widely available, to dissuade women from misusing the drug.

Moebius syndrome and central respiratory dysfunction

Two infants, 18 months and 4 months of age, who were born with bilateral VI and VII nerve palsy (Moebius syndrome) experienced central respiratory failure requiring persistent ventilation. The computed tomography scan showed small brainstem tegmental calcifications. These findings suggest intrauterine brainstem necrosis including the respiratory center and poor prognosis for independent respiration.

Uterine contraction in the development of Möbius syndrome

We report a patient with Möbius syndrome. The birth defect in this child is probably the result of both vasoconstriction and uterine contractions brought on by ergotamine taken during the sixth week of pregnancy. We propose that vasoconstrictive or mechanical effects, or both, of abortifacient drugs such as ergotamine and misoprostol may account for other cases of Möbius syndrome, and we suggest that uterine contraction from any cause, at about the sixth or seventh week of pregnancy, may cause this birth defect. Further observational studies are needed to verify this hypothesis.

Two cases of maternal antenatal splenic rupture and hypotension associated with Moebius syndrome and cerebral palsy in offspring. Further evidence for a utero placental vascular aetiology for the Moebius syndrome and some cases of cerebral palsy

We wish to report two cases of congenital abnormality after antenatal car accidents resulting in ruptured spleen and severe hypotension in the mothers at 8 and 14 weeks gestation. The first case had the classical Moebius syndrome with 6th and 7th cranial nerve palsy with abnormal brain stem evoked responses, presumably due to hypoxic/ischaemic brain stem damage and the second case had severe retardation and hypertonic cerebral palsy which at post mortem was found to be due to old hypoxic/ischaemic lesions to the caudate nucleus putamen and striatum.

CONCLUSION

The cases described provide evidence that severe maternal hypotension during pregnancy can be associated with lesions to the midbrain and brain stem of offspring. The mechanism is probably utero-placental insufficiency, and extrapolation from these two unusual cases would support utero-placental insufficiency as a cause of Moebius syndrome and limb deficiency after chorionic villus sampling.

Embryological origin for autism: developmental anomalies of the cranial nerve motor nuclei

The underlying brain injury that leads to autism has been difficult to identify. The diagnostic criteria of the disease are not readily associated with any brain region or system, nor are they mimicked by vascular accidents, tumors, or degenerative neurological diseases occurring in adults. Fortuitously, a recent report of autism induced by thalidomide exposure provides evidence that the disease originates by an injury at the time of closure of the neural tube. The human data suggest that the initiating lesion includes the motor cranial nerve nuclei. To test this hypothesis, we first examined motor nuclei in the brainstem of a human autistic case. The autopsy brain exhibited near-complete absence of the facial nucleus and superior olive along with shortening of the brainstem between the trapezoid body and the inferior olive. A similar deficit has been reported in Hoxa-1 gene knockout mice in which pattern formation of the hindbrain is disrupted during neurulation. Alternatively, exposure to antimitotic agents just after neural tube closure could produce the observed pattern of deficits. Thus, the lesions observed in the autopsy case appear to match those predicted by the thalidomide cases in both time of origin and central nervous system (CNS) location. To produce similar brain lesions experimentally, we exposed rat embryos to valproic acid, a second teratogen newly linked to autism. Dams received 350 mg/kg of valproic acid (VPA) on day 11.5 (the day of neural tube closure), day 12, or day 12.5 gestation. Each treatment significantly reduced the number of motor neurons counted in matched sections of the earliest-forming motor nuclei (V, XII), and progressively later exposures affected the VIth and IIIrd cranial nerve nuclei. All treatments spared the facial nucleus, which forms still later. Counts from the mesencephalic nucleus of trigeminal, the dorsal motor nucleus of the vagus, and the locus ceruleus were not affected by exposure to VPA, even though these nuclei form during the period when exposure occurred. Despite its effects on the motor nuclei, valproic acid exposure did not alter the further development of the brain in any obvious way. Treated animals were robust and had no external malformations. The autopsy data and experimental data from rats confirm that CNS injuries occurring during or just after neural tube closure can lead to a selective loss of neurons derived from the basal plate of the rhombencephalon. The results add two new lines of evidence that place the initiating injury for autism around the time of neural tube closure.

Arthrogryposis associated with unsuccessful attempts at termination of pregnancy

We report three cases of failed termination of pregnancy in which the children were subsequently born with arthrogryposis (AMC) (multiple congenital contractures). Arthrogryposis is a sign with many causes. We suggest that the multiple congenital contractures seen in these children are due to vascular compromise during the attempted termination with secondary loss of functional neurons leading to fetal akinesia and subsequent contractures. Two of the children have additional evidence of intrauterine vascular compromise. Limitation of movement secondary to the rupture of the fetal membranes and continuous leakage of amniotic fluid after the attempted termination may have compounded the contractures in two of the children.

Moebius syndrome: a review of the anaesthetic implications

Moebius syndrome is a rare congenital anomaly characterized by multiple cranial nerve palsies, orofacial malformations and limb anomalies. This study retrospectively reviewed the anaesthetic records of 19 children with Moebius syndrome who had anaesthesia at the Royal Alexandra Hospital for Children over a 15 year period and analysed the complications which occurred. Affected children most commonly present for anaesthesia for correction of strabismus, or for orthopaedic procedures to improve limb function. Despite the abnormal facies and drooling of saliva, these children are almost always of normal intelligence. Problems can arise during anaesthesia, with a high incidence of difficult or failed intubation. The use of a facemask and spontaneous breathing technique, where appropriate, seems to present no problems and maintaining an airway in this way appears to be safe. However, the potential for problems with aspiration of oral secretions should be remembered and the use of antisialogogue premedication is recommended. Affected children have a high incidence of other anomalies, including congenital cardiac disease, spinal anomalies, corneal abrasions and peripheral neuropathies and a careful preoperative assessment is essential.