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Non-visualisation of cavum septi pellucidi: implication in prenatal diagnosis?

Hosseinzadeh K, Luo J, Borhani A, Hill L - Insights Imaging (2013)

Bottom Line: This manuscript reviews congenital anomalies and imaging findings associated with non-visualisation of the cavum septi pellucidi (CSP) found on prenatal sonogram.Isolated septal deficiency, a rare but controversial entity, is considered a variant of normal.Common pitfalls in the sonographic evaluation of CSP include columns of the fornix that mimic CSP, and prominent cavum vergae that can simulate non-visualisation of the CSP.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Presbyterian South Tower, University of Pittsburgh Medical Center, 200 Lothrop Street, Suite 3950, Pittsburgh, PA, 15213, USA, hosseinzadehk@upmc.edu.

ABSTRACT

Objective: This manuscript reviews congenital anomalies and imaging findings associated with non-visualisation of the cavum septi pellucidi (CSP) found on prenatal sonogram.

Background: Observation of a normal cavum septi pellucidi (CSP) is an important landmark in the second and third trimester prenatal ultrasound evaluation of the fetal brain, and its visualisation provides reassurance of normal central forebrain development. Non-visualisation of the CSP is a prenatal sonographic finding, which in most cases is associated with neuroanatomical anomalies that include agenesis of the corpus callosum, schizencephaly, septo-optic dysplasia, holoprosencephaly, chronic hydrocephalus and acquired fetal brain injury. Isolated septal deficiency, a rare but controversial entity, is considered a variant of normal. Common pitfalls in the sonographic evaluation of CSP include columns of the fornix that mimic CSP, and prominent cavum vergae that can simulate non-visualisation of the CSP. When non-visualisation of the CSP is suspected, magnetic resonance imaging (MRI) of the fetal brain can confirm and evaluate associated anomalies.

Conclusion: Visualisation of the CSP is an integral component of the prenatal ultrasound and its non-visualisation is associated with other malformations, diagnosis of which is aided by MRI.

Teaching points: • Cavum septi pellucidi (CSP) is an important landmark in the prenatal ultrasound evaluation of the fetal brain, and is a marker for normal central forebrain development. • Non-visualisation of the CSP is most commonly associated with other neuroanatomical abnormalities. • Examination of the fetal brain by MRI can confirm the sonographic findings and evaluate for associated anomalies.

No MeSH data available.


Related in: MedlinePlus

Severe chronic hydrocephalus: aqueductal stenosis. a Occipito-bregmatic ultrasound view at 23 weeks demonstrates non-visualisation of the CSP and moderate but non-specific bilateral symmetric ventriculomegaly of the lateral ventricles. b Axial ultrasound at 29 weeks demonstrates progression in ventriculomegaly and macrocephaly. c Axial T2-weighted MRI at 30 weeks’ gestation demonstrates absent CSP, enlargement of the third ventricle (arrow) and bilateral lateral ventricles with colpocephaly (asterisk). d Sagittal T2-weighted MRI demonstrates lack of visualisation of a fluid-filled aqueduct of Sylvius (arrow), suspicious for stenosis. Postnatal MRI following decompression of the ventricular system confirmed aqueductal stenosis
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Fig7: Severe chronic hydrocephalus: aqueductal stenosis. a Occipito-bregmatic ultrasound view at 23 weeks demonstrates non-visualisation of the CSP and moderate but non-specific bilateral symmetric ventriculomegaly of the lateral ventricles. b Axial ultrasound at 29 weeks demonstrates progression in ventriculomegaly and macrocephaly. c Axial T2-weighted MRI at 30 weeks’ gestation demonstrates absent CSP, enlargement of the third ventricle (arrow) and bilateral lateral ventricles with colpocephaly (asterisk). d Sagittal T2-weighted MRI demonstrates lack of visualisation of a fluid-filled aqueduct of Sylvius (arrow), suspicious for stenosis. Postnatal MRI following decompression of the ventricular system confirmed aqueductal stenosis

Mentions: Hydrocephalus results from an imbalance between inflow and outflow of intracranial CSF. It is caused by overproduction, decreased absorption or obstruction of the CSF. The most common aetiologies for severe chronic hydrocephalus are aqueductal stenosis and Chiari malformation. Chronic hydrocephalus and raised intraventricular pressure can result in mechanical necrosis and disruption of the CSP [12]. Aqueductal stenosis can be primary or acquired. Primary causes include congenital narrowing of the aqueduct of Sylvius that accounts for 10 % of all causes of hydrocephalus (Fig. 7) [29], aqueductal forking or the presence of a septum within the aqueduct of Sylvius. Some cases may be inherited as an X-linked recessive trait. Acquired stenosis occurs as a sequela of inflammation or haemorrhage due to intrauterine infection, such as rubella, cytomegalovirus and toxoplasmosis. Infections can cause hydrocephalus by causing inflammation of the meninges and the ependymal lining of the ventricle, leading to impaired absorption of CSF or obstruction of the CSF flow through the ventricular system. In Chiari II malformation, downward herniation of the cerebellar hemispheres and/or vermis results when a normal-sized cerebellum develops in an abnormally small posterior fossa with a low tentorial attachment [30]. It is easily diagnosed by prenatal ultrasound and is often associated with ventriculomegaly, neural tube defects and agenesis/dysgenesis of the CC. It can be difficult to distinguish between severe chronic hydrocephalus, hydranencephaly and alobar HPE on prenatal ultrasound. Alobar HPE shows a monoventricle, complete non-cleavage of the cerebral hemispheres, complete absence of the falx cerebri, CC and CSP, and associated midline facial anomalies. Severe chronic hydrocephalus shows marked ventriculomegaly of the lateral and third ventricles, macrocephaly, normal cerebral cleavage, thinned cerebral cortex, normal falx cerebri and intact CC, but there is disruption of the CSP. Hydranencephaly shows absence of the cerebral cortex, which can be confirmed by fetal MRI and will be discussed in a later section.Fig. 7


Non-visualisation of cavum septi pellucidi: implication in prenatal diagnosis?

Hosseinzadeh K, Luo J, Borhani A, Hill L - Insights Imaging (2013)

Severe chronic hydrocephalus: aqueductal stenosis. a Occipito-bregmatic ultrasound view at 23 weeks demonstrates non-visualisation of the CSP and moderate but non-specific bilateral symmetric ventriculomegaly of the lateral ventricles. b Axial ultrasound at 29 weeks demonstrates progression in ventriculomegaly and macrocephaly. c Axial T2-weighted MRI at 30 weeks’ gestation demonstrates absent CSP, enlargement of the third ventricle (arrow) and bilateral lateral ventricles with colpocephaly (asterisk). d Sagittal T2-weighted MRI demonstrates lack of visualisation of a fluid-filled aqueduct of Sylvius (arrow), suspicious for stenosis. Postnatal MRI following decompression of the ventricular system confirmed aqueductal stenosis
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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Fig7: Severe chronic hydrocephalus: aqueductal stenosis. a Occipito-bregmatic ultrasound view at 23 weeks demonstrates non-visualisation of the CSP and moderate but non-specific bilateral symmetric ventriculomegaly of the lateral ventricles. b Axial ultrasound at 29 weeks demonstrates progression in ventriculomegaly and macrocephaly. c Axial T2-weighted MRI at 30 weeks’ gestation demonstrates absent CSP, enlargement of the third ventricle (arrow) and bilateral lateral ventricles with colpocephaly (asterisk). d Sagittal T2-weighted MRI demonstrates lack of visualisation of a fluid-filled aqueduct of Sylvius (arrow), suspicious for stenosis. Postnatal MRI following decompression of the ventricular system confirmed aqueductal stenosis
Mentions: Hydrocephalus results from an imbalance between inflow and outflow of intracranial CSF. It is caused by overproduction, decreased absorption or obstruction of the CSF. The most common aetiologies for severe chronic hydrocephalus are aqueductal stenosis and Chiari malformation. Chronic hydrocephalus and raised intraventricular pressure can result in mechanical necrosis and disruption of the CSP [12]. Aqueductal stenosis can be primary or acquired. Primary causes include congenital narrowing of the aqueduct of Sylvius that accounts for 10 % of all causes of hydrocephalus (Fig. 7) [29], aqueductal forking or the presence of a septum within the aqueduct of Sylvius. Some cases may be inherited as an X-linked recessive trait. Acquired stenosis occurs as a sequela of inflammation or haemorrhage due to intrauterine infection, such as rubella, cytomegalovirus and toxoplasmosis. Infections can cause hydrocephalus by causing inflammation of the meninges and the ependymal lining of the ventricle, leading to impaired absorption of CSF or obstruction of the CSF flow through the ventricular system. In Chiari II malformation, downward herniation of the cerebellar hemispheres and/or vermis results when a normal-sized cerebellum develops in an abnormally small posterior fossa with a low tentorial attachment [30]. It is easily diagnosed by prenatal ultrasound and is often associated with ventriculomegaly, neural tube defects and agenesis/dysgenesis of the CC. It can be difficult to distinguish between severe chronic hydrocephalus, hydranencephaly and alobar HPE on prenatal ultrasound. Alobar HPE shows a monoventricle, complete non-cleavage of the cerebral hemispheres, complete absence of the falx cerebri, CC and CSP, and associated midline facial anomalies. Severe chronic hydrocephalus shows marked ventriculomegaly of the lateral and third ventricles, macrocephaly, normal cerebral cleavage, thinned cerebral cortex, normal falx cerebri and intact CC, but there is disruption of the CSP. Hydranencephaly shows absence of the cerebral cortex, which can be confirmed by fetal MRI and will be discussed in a later section.Fig. 7

Bottom Line: This manuscript reviews congenital anomalies and imaging findings associated with non-visualisation of the cavum septi pellucidi (CSP) found on prenatal sonogram.Isolated septal deficiency, a rare but controversial entity, is considered a variant of normal.Common pitfalls in the sonographic evaluation of CSP include columns of the fornix that mimic CSP, and prominent cavum vergae that can simulate non-visualisation of the CSP.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Presbyterian South Tower, University of Pittsburgh Medical Center, 200 Lothrop Street, Suite 3950, Pittsburgh, PA, 15213, USA, hosseinzadehk@upmc.edu.

ABSTRACT

Objective: This manuscript reviews congenital anomalies and imaging findings associated with non-visualisation of the cavum septi pellucidi (CSP) found on prenatal sonogram.

Background: Observation of a normal cavum septi pellucidi (CSP) is an important landmark in the second and third trimester prenatal ultrasound evaluation of the fetal brain, and its visualisation provides reassurance of normal central forebrain development. Non-visualisation of the CSP is a prenatal sonographic finding, which in most cases is associated with neuroanatomical anomalies that include agenesis of the corpus callosum, schizencephaly, septo-optic dysplasia, holoprosencephaly, chronic hydrocephalus and acquired fetal brain injury. Isolated septal deficiency, a rare but controversial entity, is considered a variant of normal. Common pitfalls in the sonographic evaluation of CSP include columns of the fornix that mimic CSP, and prominent cavum vergae that can simulate non-visualisation of the CSP. When non-visualisation of the CSP is suspected, magnetic resonance imaging (MRI) of the fetal brain can confirm and evaluate associated anomalies.

Conclusion: Visualisation of the CSP is an integral component of the prenatal ultrasound and its non-visualisation is associated with other malformations, diagnosis of which is aided by MRI.

Teaching points: • Cavum septi pellucidi (CSP) is an important landmark in the prenatal ultrasound evaluation of the fetal brain, and is a marker for normal central forebrain development. • Non-visualisation of the CSP is most commonly associated with other neuroanatomical abnormalities. • Examination of the fetal brain by MRI can confirm the sonographic findings and evaluate for associated anomalies.

No MeSH data available.


Related in: MedlinePlus