Cerebro-ocular dysplasia--muscular dystrophy (Walker Warburg) syndrome. Findings in 20-week-old fetus

The corticospinal tract: Evolution, development, and human disorders

The corticospinal tract (CST) plays a major role in cortical control of spinal cord activity. In particular, it is the principal motor pathway for voluntary movements. Here, we discuss: (i) the anatomic evolution and development of the CST across mammalian species, focusing on its role in motor functions; (ii) the molecular mechanisms regulating corticospinal tract formation and guidance during mouse development; and (iii) human disorders associated with abnormal CST development. A comparison of CST anatomy and development across mammalian species first highlights important similarities. In particular, most CST axons cross the anatomical midline at the junction between the brainstem and spinal cord, forming the pyramidal decussation. Reorganization of the pattern of CST projections to the spinal cord during evolution led to improved motor skills. Studies of the molecular mechanisms involved in CST formation and guidance in mice have identified several factors that act synergistically to ensure proper formation of the CST at each step of development. Human CST developmental disorders can result in a reduction of the CST, or in guidance defects associated with abnormal CST anatomy. These latter disorders result in altered midline crossing at the pyramidal decussation or in the spinal cord, but spare the rest of the CST. Careful appraisal of clinical manifestations associated with CST malformations highlights the critical role of the CST in the lateralization of motor control. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 810-829, 2017.

Two Hundred Thirty-Six Children With Developmental Hydrocephalus: Causes and Clinical Consequences

Few systematic assessments of developmental forms of hydrocephalus exist. We reviewed magnetic resonance images (MRIs) and clinical records of patients with infancy-onset hydrocephalus. Among 411 infants, 236 had hydrocephalus with no recognizable extrinsic cause. These children were assigned to 1 of 5 subtypes and compared on the basis of clinical characteristics and developmental and surgical outcomes. At an average age of 5.3 years, 72% of children were walking independently and 87% could eat by mouth; in addition, 18% had epilepsy. Distinct patterns of associated malformations and syndromes were observed within each subtype. On average, children with aqueductal obstruction, cysts, and encephaloceles had worse clinical outcomes than those with other forms of developmental hydrocephalus. Overall, 53% of surgically treated patients experienced at least 1 shunt failure, but hydrocephalus associated with posterior fossa crowding required fewer shunt revisions. We conclude that each subtype of developmental hydrocephalus is associated with distinct clinical characteristics, syndromology, and outcomes, suggesting differences in underlying mechanisms.

Infantile hydrocephalus: a review of epidemiology, classification and causes

Hydrocephalus is a common but complex condition caused by physical or functional obstruction of CSF flow that leads to progressive ventricular dilatation. Though hydrocephalus was recently estimated to affect 1.1 in 1000 infants, there have been few systematic assessments of the causes of hydrocephalus in this age group, which makes it a challenging condition to approach as a scientist or as a clinician. Here, we review contemporary literature on the epidemiology, classification and pathogenesis of infantile hydrocephalus. We describe the major environmental and genetic causes of hydrocephalus, with the goal of providing a framework to assess infants with hydrocephalus and guide future research.

Intracellular binding of fukutin and α-dystroglycan: Relation to glycosylation of α-dystroglycan

The functions of fukutin, a gene product responsible for Fukuyama type congenital muscular dystrophy, still remain unclear, although a relation to the glycosylation of alpha-dystroglycan is presumed. To investigate the functions of fukutin, immunohistochemistry, examination using cultured astrocytes, enzyme-linked immunosorbent assay (ELISA)-based binding assay and immunoprecipitation were performed using control muscle and central nervous system tissues. Immunohistochemistry showed that alpha-dystroglycan and fukutin were co-expressed, especially in the glial cytoplasm and glia limitans of the central nervous system. An anti-fukutin antibody added to the culture medium did not bring about any changes in the astrocytes cultured on laminin-coated dishes. Together with the immunohistochemical results, the intracellular function of fukutin is considered. ELISA-based binding assay and immunoprecipitation may suggest the direct binding of fukutin and alpha-dystroglycan, at least in part. Fukutin seems to bind to both the hypoglycosylated and fully glycosylated form of alpha-dystroglycan, and seems bind to the core area rather than the sugar chain of alpha-dystroglycan. Fukutin may directly interact with alpha-dystroglycan during glycosylation, but further examinations are needed to confirm these details.

Prenatal US and MR imaging findings of lissencephaly: review of fetal cerebral sulcal development

The cerebral cortex develops in three overlapping stages: cell proliferation, neuronal migration, and cortical organization. Abnormal neuronal migration may result in lissencephaly, which is characterized by either the absence (agyria) or the paucity (pachygyria) of cerebral convolutions. The two main clinicopathologic types of lissencephaly may be differentiated according to their prenatal imaging features. Other cranial and extracranial abnormalities also may occur in association with lissencephaly. The prognosis is often poor, but prenatal diagnosis allows appropriate counseling and optimization of obstetric management. Familiarity with the normal ultrasonographic (US) and magnetic resonance (MR) imaging appearances of the fetal cerebral cortex at various stages of gestation is essential for the early detection of abnormal sulcal development. The primary fissures and sulci that can be examined with prenatal US and MR imaging include the parieto-occipital fissure, calcarine fissure, cingulate sulcus, convexity sulci, and sylvian fissure and insula.

Severe, fetal-onset form of olivopontocerebellar hypoplasia in three sibs: PCH type 5?

We present three siblings with a precise onset of fetal seizure-like activity who had severe olivopontocerebellar hypoplasia (OPCH) and degeneration. Autopsies at 20, 27, and 37 weeks gestation showed diffuse central nervous system volume loss that was most marked for the cerebellum and brain stem structures. Neuropathological abnormalities included dysplastic, C-shaped inferior olivary nuclei, absent or immature dentate nuclei, and cell paucity more marked for the cerebellar vermis than the hemispheres. Delayed development was seen in layer 2 of the cerebral cortex and in Purkinje cells of the cerebellum. Prenatal monitoring defined a developmental window of 16-18 weeks gestation when ultrasonic assessment of cerebellar width was used for prenatal diagnosis. We discuss our findings in the context of the differential diagnosis for infantile (O)PCH and propose a classification scheme for the pontocerebellar hypoplasias. These patients represent the earliest reported with OPCH and provide unique information regarding the developmental neuropathology of this condition.

Difficulties with prenatal diagnosis of the Walker-Warburg syndrome

We describe a postnatally diagnosed case of Walker-Warburg syndrome--a form of congenital muscular dystrophy with lissencephaly and eye abnormalities. We reviewed the literature to highlight its clinico-radiological diagnostic features and discuss the difficulties encountered with prenatal diagnosis, especially in cases with no positive family history. An increased awareness of this rare but lethal condition, and a high index of suspicion during routine antenatal ultrasound, could prompt further advanced fetal ultrasonography and magnetic resonance imaging, and aid in timely prenatal diagnosis, management, and counseling.

Expression of genes related to muscular dystrophy with lissencephaly

There is a group of congenital muscular dystrophies accompanying the brain lesions termed cobblestone lissencephaly. Abnormal glia limitans could be considered the major pathogenesis of cobblestone lissencephaly. In this group, protein-O-linked mannose-beta1,2-N-acetylglucosaminyltransferase and protein-O-mannosyltransferase 1 are considered to be responsible for muscle-eye-brain disease and Walker-Warburg syndrome, respectively, by glycosylation of alpha-dystroglycan. However, the functions of fukutin, a gene responsible for Fukuyama type congenital muscular dystrophy, are still unclear. In this study, expression of the three aforementioned genes was compared by in situ hybridization in control cases to elucidate the functions of fukutin. Immunohistochemistry of fukutin and alpha-dystroglycan was also performed. In the central nervous system, all three genes were expressed in astrocytes and in immature neurons. A few mature neurons expressed fukutin, but many expressed the other two genes. All genes were expressed in various non-nervous tissues including tissues relating to secretion. Fukutin and alpha-dystroglycan were generally colocalized, but localization was not always the same, especially in the liver. Fukutin may be associated with the glycosylation of alpha-dystroglycan, and expression in astrocytes may indicate a relation to glia limitans. The roles of fukutin in mature neurons may be less critical compared with the other two genes. Additional functions of fukutin, especially in the liver, are suspected.

Aberrant neuronal migration in the brainstem of fukuyama-type congenital muscular dystrophy

We examined the brainstem of 10 patients with Fukuyama-type congenital muscular dystrophy (FCMD). In the midbrain we noted leptomeningeal glioneuronal heterotopia (LGH) (n = 9) and intramural "micropolygyria" (n = 1) in the tectum, as well as tyrosine hydroxylase-positive ectopic neurons/fibers ventral to the cerebral peduncle (n = 3). In the pontomedullary region, glial fibrillary acidic protein-positive subpial tissue intermingled with neurons and myelinated fibers was present in the ventrolateral pontine surface in all cases and extended over the lateral surface of the upper medulla oblongata. This subpial gliotic band was often contiguous with the extra-pial LGH tissues. The gliotic band protruded from the ventrolateral pontine surface in 3 cases and appeared to include ectopic neurons of the pontine nucleus. Disarrangement of the arcuate nuclei (n = 3) was also noted in the medulla oblongata. We hypothesize that both the radial and tangential neuronal migration systems are disrupted in the FCMD brainstem in addition to altered neuronal migration in the cerebral and cerebellar cortex. Fukutin protein may play a part in the morphogenesis of certain neuronal structures in the brainstem and the dysplastic structure termed "aberrant pyramidal tract" in previous reports may essentially result from an ectopic migration of pontine nucleus neurons.

Clinicopathological report of cerebroocular myopathy syndrome

PURPOSE

To report a case of cerebroocular myopathy syndrome with a focal absence of the Descemet membrane.

DESIGN

Clinicopathological case report.

METHODS

A clinical and histopathologic examination of eye, brain, and viscera of a white male newborn of normal term, who died at 11 days of age with the diagnosis of cerebroocular myopathy syndrome.

RESULTS

The autopsy revealed hazy left cornea, hypoplasia of the cerebellum, and corpus collusum with mild microcephaly. Microscopy of the left eye showed the additional findings of a central focal defect of the Descemet membrane with an absence of the posterior third of central corneal stroma and delicate fibrous strands connected to the iris.

CONCLUSION

The absence of the Descemet membrane and the missing posterior corneal keratocytes as well as the fibrous strands connecting the iris are findings to be added to the previously reported signs of cerebro-ocular myopathy.

Prenatal diagnosis of retinal nonattachment in the Walker-Warburg syndrome

We report on the prenatal ultrasonographic diagnosis of Walker-Warburg syndrome based on cerebral and ocular findings. The ultrasound study done at 37 weeks gestation documented hydrocephalus and retinal nonattachment consistent with this syndrome. The ability to detect retinal nonattachment prenatally may have implications for the prenatal diagnosis of other conditions which have early retinal nonattachment as one of their findings. However, it is uncertain how early in pregnancy this defect can be detected.

Developmental aspects of type II lissencephaly. Comparative study of dysplastic lesions in fetal and post-natal brains

We report neuropathological studies of five cases of type II lissencephaly from three fetuses and two infants. This comparative study allowed us to determine the developmental course of the cerebral lesions. Two distinct developmental events seem to generate this type of brain malformation: firstly, an early disturbance in cortex formation, which results both from a disorder of radial migration and a pial barrier disruption; secondly, a late perturbation of cerebral surface organization, resulting in fusion of the cerebral surface. All these features can be related to a primitive meningeal pathology, and more generally, to a neurocristopathy. Accordingly to our observations, this brain malformation appears during both migrational and post-migrational stages and may be considered more like a polymicrogyria than a lissencephaly.

Walker-Warburg syndrome: report of three affected sibs

Walker-Warburg syndrome (WWS) is a lethal, autosomal recessive disorder characterized by Type II lissencephaly, retinal malformation, cerebellar malformation, and congenital muscular dystrophy. We report on 3 sibs with WWS born to a consanguineous couple. The fetal hydrocephalus associated with this syndrome, while not consistent or necessary for diagnosis, is the key manifestation for its prenatal detection. These sibs illustrate the importance of a careful search for associated malformation(s) in a fetus or newborn infant with hydrocephalus and the potential pitfalls of accurate genetic risk estimation in families of such propositi.

Prenatal diagnosis and management of fetal hydrocephaly and lissencephaly

Two cases of prenatal diagnosis of lissencephaly are presented in the context of a series of 118 cases of prenatally diagnosed hydrocephalus. Within this series there was one case of Walker-Warburg syndrome and another of Miller-Dieker syndrome. It is stressed that the cases reported here of ventriculomegaly diagnosed in utero show a very different outcome from those in published studies of fetal hydrocephalus which only deal with patients in whom the diagnosis was determined after birth. In those postnatal series there is a considerable selection bias, and the fate of the fetuses reported here was much worse than in postnatal series. Of the 118 fetuses 6 had fetal infections, 6 had chromosomal abnormalities, 26 had associated spina bifida, 64 fetuses had associated other anomalies, and only 28 had isolated hydrocephalus. Although it is difficult to determine the prognosis individually after prenatal diagnosis of ventriculomegaly, the data presented here may be helpful in counseling parents prenatally. The counseling should be performed with the collaboration of obstetricians, pediatricians, surgeons, and geneticists.

Neuropathology of lissencephalies

The neuropathological findings at autopsy in four cases of type I and three of type II lissencephaly are presented. Type I lissencephaly is characterized by agyriapachygyria with a markedly thickened cerebral cortex with four coarse histological layers. The normally myelinated white matter, often with neuronal heterotopias, is very narrow, and the gray-to-white matter ratio is inverted (about 4:1); there are no white-gray interdigitations. Claustrum and capsula extrema are absent. Ventricular dilatation is present, especially of the occipital horns. In the hypoplastic brain stem large olivary heterotopias can often be observed. Severe cerebellar malformations, obstructive hydrocephalus, severe eye abnormalities, and congenital muscular dystrophy are not seen. Clinically, type I lissencephaly presents as "isolated lissencephaly sequence" or as "Miller-Dieker syndrome" with characteristic facial dysmorphism. The long survival of 20 years achieved by one of our patients is very uncommon. Type II lissencephaly is characterized by widespread agyria. Usually, obstructive hydrocephalus is present with a thin cerebral mantle showing a slightly thickened cortex and a narrow, hypomyelinated white matter often with neuronal heterotopias (gray-to-white matter ratio about 1:1). The border between gray and white matter is blurred. Claustrum and capsula extrema are absent. Histologically, the cortex appears disorganized without layering; widespread leptomeningeal gliomesenchymal proliferations and glioneuronal heterotopias are present.(ABSTRACT TRUNCATED AT 250 WORDS)

Fetal type II lissencephaly: a case report

Type II lissencephaly is a rare cortical malformation associated with a number of clinical syndromes, including Walker-Warburg syndrome and some forms of congenital muscular dystrophy. The neuropathology of a 20-week fetus is described showing the pathogenesis of the malformation, which appears to result from abnormal migration of neurons through the pial-glial barrier into the leptomeninges.

Development of the cortical dysplasia of type II lissencephaly

A detailed neuropathological study of five immature brains with type II lissencephaly is reported. The cases described include two pairs of siblings. One infant survived for 2 months after birth, the others died at 18, 20, 20 and 32 weeks of gestation. This series of cases demonstrates the sequence in which the malformation develops from mid-gestation to post-natal life and shows that type II lissencephaly is not an intracortical malformation but is the result of massive glial and neuronal ectopia in the leptomeninges. This results from a failure of arrest of neuronal migration due to defects in the integrity of the pial/glial barrier.

Focal cerebral anomalies and retinal dysplasia in a 23-24-week-old fetus

A 23-24-week-old fetus was the product of a normal pregnancy terminated because of diaphragmatic hernia and hydrocephalus diagnosed by ultrasound. Karyotype on fetal blood was normal. At autopsy, hydrocephalus was associated with multiple large intrameningeal nodules and focal cerebral dysplasia resembling type II lissencephaly. In addition, many structures of the brainstem were dysmorphic and the retina showed multiple rosettes. Skeletal muscle was normal. The peculiar features described in this case pose problems for classification and genetic implications of the anomalies.