Rhombencephalosynapsis as a cause of aqueductal stenosis

An under-recognized association in hydrocephalic children

Matthew T. Whitehead, Asim Choudhri, John Grimm, Marvin D. Nelson

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Background: Rhombencephalosynapsis is a rare genetic aberration characterized by variable vermian hypoplasia/aplasia in conjunction with united cerebellar hemispheres. Genetic defects in the isthmic organizer at the mesencephalic-metencephalic junction are presumably responsible for the associated aqueductal stenosis. Objective: We performed a retrospective review of 20 children with rhombencephalosynapsis to evaluate for and emphasize the association of aqueductal stenosis and hydrocephalus. Materials and methods: We retrospectively reviewed the MR and CT images of 20 children (0-11 years old) with rhombencephalosynapsis encountered at two academic children's hospitals. Rhombencephalosynapsis spectrum severity was graded based on pre-existing literature. We analyzed examinations for ventriculomegaly and degree of aqueductal stenosis. The collicular distances were measured from the collicular apices. Imaging studies were also analyzed for malformations of cortical and cerebellar development. Results: Thirteen of the 20 children (65%) with rhombencephalosynapsis presented with clinical or imaging evidence of hydrocephalus and aqueductal stenosis, principally involving the caudal cerebral aqueduct. All children with aqueductal stenosis had collicular fusion. All six children with complete rhombencephalosynapsis had aqueductal stenosis. The cerebral aqueduct varied from normal to stenotic in children with incomplete rhombencephalosynapsis. Corpus callosum dysgenesis was present in four children. Conclusion: Aqueductal stenosis in the setting of rhombencephalosynapsis is an under-recognized cause of noncommunicating hydrocephalus. Our findings support the hypothesis that a defect involving the common gene(s) responsible for the differentiation and development of both the roof plate and midline cerebellar primordium at the mesencephalon/first rhombomere junction may be responsible for the association of aqueductal stenosis and rhombencephalosynapsis.

Original languageEnglish (US)
Pages (from-to)849-856
Number of pages8
JournalPediatric Radiology
Volume44
Issue number7
DOIs
StatePublished - Jan 1 2014

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Hydrocephalus
Cerebral Aqueduct
Agenesis of Corpus Callosum
Malformations of Cortical Development
Mesencephalon

All Science Journal Classification (ASJC) codes

  • Pediatrics, Perinatology, and Child Health
  • Radiology Nuclear Medicine and imaging

Cite this

Rhombencephalosynapsis as a cause of aqueductal stenosis : An under-recognized association in hydrocephalic children. / Whitehead, Matthew T.; Choudhri, Asim; Grimm, John; Nelson, Marvin D.

In: Pediatric Radiology, Vol. 44, No. 7, 01.01.2014, p. 849-856.

Research output: Contribution to journalArticle

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abstract = "Background: Rhombencephalosynapsis is a rare genetic aberration characterized by variable vermian hypoplasia/aplasia in conjunction with united cerebellar hemispheres. Genetic defects in the isthmic organizer at the mesencephalic-metencephalic junction are presumably responsible for the associated aqueductal stenosis. Objective: We performed a retrospective review of 20 children with rhombencephalosynapsis to evaluate for and emphasize the association of aqueductal stenosis and hydrocephalus. Materials and methods: We retrospectively reviewed the MR and CT images of 20 children (0-11 years old) with rhombencephalosynapsis encountered at two academic children's hospitals. Rhombencephalosynapsis spectrum severity was graded based on pre-existing literature. We analyzed examinations for ventriculomegaly and degree of aqueductal stenosis. The collicular distances were measured from the collicular apices. Imaging studies were also analyzed for malformations of cortical and cerebellar development. Results: Thirteen of the 20 children (65{\%}) with rhombencephalosynapsis presented with clinical or imaging evidence of hydrocephalus and aqueductal stenosis, principally involving the caudal cerebral aqueduct. All children with aqueductal stenosis had collicular fusion. All six children with complete rhombencephalosynapsis had aqueductal stenosis. The cerebral aqueduct varied from normal to stenotic in children with incomplete rhombencephalosynapsis. Corpus callosum dysgenesis was present in four children. Conclusion: Aqueductal stenosis in the setting of rhombencephalosynapsis is an under-recognized cause of noncommunicating hydrocephalus. Our findings support the hypothesis that a defect involving the common gene(s) responsible for the differentiation and development of both the roof plate and midline cerebellar primordium at the mesencephalon/first rhombomere junction may be responsible for the association of aqueductal stenosis and rhombencephalosynapsis.",
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