Telencephalosynapsis (synencephaly) and rhombencephalosynapsis with posterior fossa ventriculocele (‘Dandy-Walker cyst’): an unusual aberrant syngenetic complex

Sergi, Consolato; Hentze, Sabine; Sohn, Christof; Voigtländer, Theda; Jung, Christine; Schmitt, Horst P.

doi:10.1016/s0387-7604(97)00050-8

Cited by 24 publications

(29 citation statements)

References 27 publications

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“…In the whole literature, the cerebellum is described as more or less hypoplastic, as conWrmed by our study where biometric data were normal in 50% of cases, and in the most severe forms fastigium and Xocculi are not visualized, which we did not Wnd in our series. In some cases, the dentate nuclei are unfolded [47,48], as in one of our cases. Previously described cerebellar histological anomalies consist of dysplastic deep cerebellar roof nuclei and lack of cerebellar folia [47], and in one case, of dysplastic large ectopic neurons [48] which could correspond to the nonmigrated calbindin-positive Purkinje cell clusters we observed in the cerebellar white matter, and which are likely to be a frequent associated anomaly, since observed in about 20% of our cases.…”

Section: Neuropathological Descriptionssupporting

confidence: 69%

“…In some cases, the dentate nuclei are unfolded [47,48], as in one of our cases. Previously described cerebellar histological anomalies consist of dysplastic deep cerebellar roof nuclei and lack of cerebellar folia [47], and in one case, of dysplastic large ectopic neurons [48] which could correspond to the nonmigrated calbindin-positive Purkinje cell clusters we observed in the cerebellar white matter, and which are likely to be a frequent associated anomaly, since observed in about 20% of our cases. In our cases as in those described in the literature, brainstem anomalies are very infrequent.…”

Section: Neuropathological Descriptionssupporting

confidence: 69%

“…Fetal neuropathology has seldom been reported, and to our knowledge, only eight autopsy cases with neuropathological analysis have been described [26,27,[47][48][49]. In all reports, neuropathological descriptions of RS are similar and distinguish complete and partial RS, the latter suggesting that RS should be considered as a malformation with a variable degree of severity.…”

Section: Neuropathological Descriptionsmentioning

confidence: 98%

“…In patients alive, clinical prognosis depends on the severity of neurological signs, on mental retardation and long-term cognitive functions which are most often impaired, even though RS is compatible with normal cognitive functions in childhood [34,53] as well as in adulthood [2]. At the present time, the precise etiological factors responsible for this cerebellar malformation, which is supposed to occur between 28 and 42 post-conceptional days [51,55] are unknown, though several hypotheses have been proposed including teratogenic [27,47] or genetic, either chromosomal [24,54] or genetic ones [58]. Hypothetic genes implicated in early development have also been discussed [28] and up to now, no animal models have been described.…”

Section: Introductionmentioning

confidence: 99%

“…In case of ventricular dilatation, stenosis of the aqueduct of Sylvius has been observed, and histological examination revealed diVuse subpial gliosis of the tegmentum as well as an immature pattern of the ependymal lining [58]. Although there is an increasing number of prenatal diagnoses, few reports of fetal RS diagnosed on ultrasound and/or MRI screening have been published and, to our knowledge, only eight autopsy cases with neuropathological Wndings have been reported so far [26,27,[47][48][49]. We report herein a series of 40 fetal cases with RS obtained by means of a collaborative study including 5 French centers, which made it possible to analyze the neuropathological abnormalities accurately and to describe the diVerent intraand extraneural associated anomalies, in an attempt to identify new possible syndromic entities, and to propose from all these data additional etiological hypotheses.…”

Section: Introductionmentioning

confidence: 99%

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Rhombencephalosynapsis and related anomalies: a neuropathological study of 40 fetal cases

et al. 2008

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Rhombencephalosynapsis is an uncommon cerebellar malformation deWned by vermian agenesis with fusion of the hemispheres and of the dentate nuclei. Embryologic and genetic mechanisms are still unknown, and to date, no animal models are available. Ultrasound diagnosis is generally suspected after 22 weeks of gestation, and usually the abnormality is suggested by ventriculomegaly. Morphological analysis of 40 fetuses after medical termination of pregnancy allowed us to conWrm that rhombencephalosynapsis was always associated with other brain abnormalities or malformations: Purkinje cell heterotopias, fusion of colliculi, forking and/or atresia of the aqueduct and of the third ventricle resulting in a fusion of the thalami, agenesis of the corpus callosum, lobar holoprosencephaly and neural tube defects. Pons and medulla were very infrequently abnormal. Furthermore, complete autopsy made it possible to separate either pure neurologic phenotypes, or associated with extraneural anomalies from syndromic forms: Gomez-Lopez-Hernandez syndrome (1 case) and VACTERL-H syndrome (6 cases). The number of our fetal cases strongly suggests that VACTERL-H association related with rhombencephalosynapsis emerges as a non-random association. Furthermore, recurrence and consanguinity were noted in two diVerent families, which argue for a sporadic or inherited cause. From our results, it could be suggested that rhombencephalosynapsis may be due to defective genes regulating formation of the roof plate and the development of midline cerebellar primordium at the junction of the mesencephalon and of the Wrst rhombomere.

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Section: Neuropathological Descriptionssupporting

confidence: 69%

Section: Neuropathological Descriptionssupporting

confidence: 69%

Section: Neuropathological Descriptionsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Rhombencephalosynapsis and related anomalies: a neuropathological study of 40 fetal cases

et al. 2008

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Cerebellum—small brain but large confusion: A review of selected cerebellar malformations and disruptions

Boltshauser

2004

American J of Med Genetics Pt A

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Defining and classifying congenital disorders of the cerebellum can be difficult and confusing. One reason is that some abnormalities called "malformations" are not truly (primary) developmental malformations. This applies to Chiari I "malformations" as well as to Chiari II "malformations." The latter results mainly from a prenatal cerebrospinal fluid (CSF) leak. Also disruptive cerebellar lesions are not uncommon, examples being the "vanishing cerebellum" in myelomeningocele, cerebellar lesions in very low birth weight prematurely born infants, unilateral cerebellar hypoplasia/aplasia, and probably some instances of cerebellar agenesis (CA). The cerebellar hypoplasias consist of a heterogeneous group of inherited and prenatally acquired conditions. The concept of pontocerebellar hypoplasias will need to be expanded beyond the two main types (PCH-1 and PCH-2), and demonstrate that a classification system of cerebellar malformations cannot be based on neuroimaging criteria only. Additional studies are expected to show that this also applies to the molar tooth sign, which was initially described in Joubert syndrome (JS). The JS is the prototype of midhindbrain malformation, but its delineation is still unsolved. JS may well be an overdiagnosed entity; many cases likely not having JS are on record. Rhombencephalosynapsis (RS) has been increasingly diagnosed with the advent of neuroimaging. No familial cases have been observed. Although many affected individuals have variable impairments, RS can be found in children with normal cognitive function. In this review, some of the cerebellar anomalies are briefly discussed.

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Beyond Gómez‐López‐Hernández syndrome: Recurring phenotypic themes in rhombencephalosynapsis

Tully

Dempsey

Ishak

et al. 2012

American J of Med Genetics Pt A

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Rhombencephalosynapsis (RES) is an uncommon cerebellar malformation characterized by fusion of the hemispheres without an intervening vermis. Frequently described in association with Gómez-López-Hernández syndrome, RES also occurs in conjunction with VACTERL features and with holoprosencephaly (HPE). We sought to determine the full phenotypic spectrum of RES in a large cohort of patients. Information was obtained through database review, patient questionnaire, radiographic and morphologic assessment, and statistical analysis. We assessed 53 patients. 33 had alopecia, 3 had trigeminal anesthesia, 14 had VACTERL features and 2 had HPE with aventriculy. Specific craniofacial features were seen throughout the cohort, but were more common in patients with alopecia. We noted substantial overlap between groups. We conclude that although some distinct subgroups can be delineated, the overlapping features seen in our cohort suggest an underlying spectrum of RES-associated malformations rather than a collection of discrete syndromes.

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Telencephalosynapsis (synencephaly) and rhombencephalosynapsis with posterior fossa ventriculocele (‘Dandy-Walker cyst’): an unusual aberrant syngenetic complex

Cited by 24 publications

References 27 publications

Rhombencephalosynapsis and related anomalies: a neuropathological study of 40 fetal cases

Rhombencephalosynapsis and related anomalies: a neuropathological study of 40 fetal cases

Cerebellum—small brain but large confusion: A review of selected cerebellar malformations and disruptions

Beyond Gómez‐López‐Hernández syndrome: Recurring phenotypic themes in rhombencephalosynapsis

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