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Published on: February 29, 2020
Supratentorial abnormalities in the Chiari II malformation, II: tectal morphologic changes
Andrew L Callen1, Joseph W Stengel, Roy A Filly
1Department of Radiology, University of California San Francisco, San Francisco, CA 94143-0628, USA.
Summary
Prenatal ultrasound can detect tectal abnormalities in fetuses with myelomeningocele, aiding in the diagnosis of Chiari II malformation. These findings are common and can indicate the severity of the condition.
Area of Science:
- Medical Imaging
- Fetal Medicine
- Neurology
Background:
- Fetal myelomeningocele diagnosis has improved with a focus on cranial abnormalities.
- Intracranial diagnosis relies on posterior fossa abnormalities.
- Tectal morphologic characteristics are under-recognized in sonographic literature.
Purpose of the Study:
- To analyze the frequency of tectal abnormalities in fetal myelomeningocele cases.
- To describe technical aspects improving visualization of tectal abnormalities.
- To assess the utility of tectal morphology in diagnosing Chiari II malformation.
Main Methods:
- Retrospective review of obstetric sonograms from 1999-2007.
- Identification of fetal myelomeningocele cases.
- Focus on intracranial findings, specifically tectal elongation or 'beaking'.
Main Results:
- 89 fetuses with myelomeningocele were identified.
- 66% (59/89) showed abnormal tectal shape.
- Tectal abnormalities were observed regardless of gestational age (before/after 24 weeks) and increased with posterior fossa severity.
Conclusions:
- Tectal morphologic alteration is a frequent supratentorial finding in Chiari II malformation on prenatal sonography.
- It is a useful indicator for the presence and potential severity of Chiari II malformation.
- This finding is valuable both before and after 24 weeks' gestation.
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