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DOI: 10.1148/rg.253045103
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Fetal Schizencephaly: Pre- and Postnatal Imaging with a Review of the Clinical Manifestations1

Karen Y. Oh, MD, Anne M. Kennedy, MD, Antonio E. Frias, Jr, MD and Janice L. B. Byrne, MD

1 From the Departments of Radiology (K.Y.O., A.M.K.) and Obstetrics and Gynecology (A.E.F., J.L.B.B.), University of Utah, 30 N 1900 E, SOM1A71, Salt Lake City, UT 84132. Presented as an education exhibit at the 2003 RSNA Scientific Assembly. Received May 13, 2004; revision requested June 8; revision received and accepted July 12. All authors have no financial relationships to disclose.


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  		Figure 1a. Patient 1.  (a) Axial US image shows bilateral open-lip wedge-shaped defects in the parietotemporal regions. The thalami are not fused. (b) Axial US image shows flow in the vessels of the circle of Willis. This finding proves that the defects are not due to vascular occlusion.

 


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  		Figure 1b. Patient 1.  (a) Axial US image shows bilateral open-lip wedge-shaped defects in the parietotemporal regions. The thalami are not fused. (b) Axial US image shows flow in the vessels of the circle of Willis. This finding proves that the defects are not due to vascular occlusion.

 


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  		Figure 2. Patient 2.  Axial US image shows bilateral giant, open-lip, wedge-shaped defects.

 


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  		Figure 3. Patient 3.  Coronal US image shows a focal small schizencephalic defect (arrow). Note the absent CSP and the ventriculomegaly; the defect extends from the ventricle to the pial surface. This appearance can be difficult to differentiate from porencephaly. However, accurate diagnosis is important because some causes of porencephaly, such as intracranial hemorrhage, can be associated with a significant risk of recurrence.

 


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  		Figure 4a. Patient 4.  (a) Axial US image shows bilateral large schizencephalic defects and absence of the CSP. A Dandy-Walker variant was also suspected. (b) Coronal SSFSE T2-weighted fetal MR image obtained subsequently shows the large defects. Note that the thalami (T) are not fused; this finding allows differentiation of this malformation from alobar holoprosencephaly. A roofing membrane is partially visualized (arrows). (c) Axial SSFSE T2-weighted fetal MR image shows a Dandy-Walker cyst (arrows) and the schizencephalic defects. T = thalami. (d) Sagittal SSFSE T2-weighted fetal MR image shows the schizencephalic defects and the Dandy-Walker malformation. (e) Postnatal axial computed tomographic (CT) image obtained through the brain shows that the large bilateral clefts communicate with the ventricles.

 


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  		Figure 4b. Patient 4.  (a) Axial US image shows bilateral large schizencephalic defects and absence of the CSP. A Dandy-Walker variant was also suspected. (b) Coronal SSFSE T2-weighted fetal MR image obtained subsequently shows the large defects. Note that the thalami (T) are not fused; this finding allows differentiation of this malformation from alobar holoprosencephaly. A roofing membrane is partially visualized (arrows). (c) Axial SSFSE T2-weighted fetal MR image shows a Dandy-Walker cyst (arrows) and the schizencephalic defects. T = thalami. (d) Sagittal SSFSE T2-weighted fetal MR image shows the schizencephalic defects and the Dandy-Walker malformation. (e) Postnatal axial computed tomographic (CT) image obtained through the brain shows that the large bilateral clefts communicate with the ventricles.

 


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  		Figure 4c. Patient 4.  (a) Axial US image shows bilateral large schizencephalic defects and absence of the CSP. A Dandy-Walker variant was also suspected. (b) Coronal SSFSE T2-weighted fetal MR image obtained subsequently shows the large defects. Note that the thalami (T) are not fused; this finding allows differentiation of this malformation from alobar holoprosencephaly. A roofing membrane is partially visualized (arrows). (c) Axial SSFSE T2-weighted fetal MR image shows a Dandy-Walker cyst (arrows) and the schizencephalic defects. T = thalami. (d) Sagittal SSFSE T2-weighted fetal MR image shows the schizencephalic defects and the Dandy-Walker malformation. (e) Postnatal axial computed tomographic (CT) image obtained through the brain shows that the large bilateral clefts communicate with the ventricles.

 


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  		Figure 4d. Patient 4.  (a) Axial US image shows bilateral large schizencephalic defects and absence of the CSP. A Dandy-Walker variant was also suspected. (b) Coronal SSFSE T2-weighted fetal MR image obtained subsequently shows the large defects. Note that the thalami (T) are not fused; this finding allows differentiation of this malformation from alobar holoprosencephaly. A roofing membrane is partially visualized (arrows). (c) Axial SSFSE T2-weighted fetal MR image shows a Dandy-Walker cyst (arrows) and the schizencephalic defects. T = thalami. (d) Sagittal SSFSE T2-weighted fetal MR image shows the schizencephalic defects and the Dandy-Walker malformation. (e) Postnatal axial computed tomographic (CT) image obtained through the brain shows that the large bilateral clefts communicate with the ventricles.

 


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  		Figure 4e. Patient 4.  (a) Axial US image shows bilateral large schizencephalic defects and absence of the CSP. A Dandy-Walker variant was also suspected. (b) Coronal SSFSE T2-weighted fetal MR image obtained subsequently shows the large defects. Note that the thalami (T) are not fused; this finding allows differentiation of this malformation from alobar holoprosencephaly. A roofing membrane is partially visualized (arrows). (c) Axial SSFSE T2-weighted fetal MR image shows a Dandy-Walker cyst (arrows) and the schizencephalic defects. T = thalami. (d) Sagittal SSFSE T2-weighted fetal MR image shows the schizencephalic defects and the Dandy-Walker malformation. (e) Postnatal axial computed tomographic (CT) image obtained through the brain shows that the large bilateral clefts communicate with the ventricles.

 


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  		Figure 5a. Patient 5.  (a) Axial US image obtained through the brain shows absence of the CSP (arrow). A small schizencephalic defect was not identified at initial prenatal US. (b) Comparison US image of an infant who was normal at birth shows a slightly prominent CSP.

 


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  		Figure 5b. Patient 5.  (a) Axial US image obtained through the brain shows absence of the CSP (arrow). A small schizencephalic defect was not identified at initial prenatal US. (b) Comparison US image of an infant who was normal at birth shows a slightly prominent CSP.

 


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  		Figure 6a. Patient 6.  (a) Axial US image shows mild ventriculomegaly (cursors) with a wedge-shaped schizencephalic defect (arrows). The CSP is absent. (b) Postnatal CT image shows the gray matter–lined defect extending from the occipital horn of the lateral ventricle to the pial surface.

 


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  		Figure 6b. Patient 6.  (a) Axial US image shows mild ventriculomegaly (cursors) with a wedge-shaped schizencephalic defect (arrows). The CSP is absent. (b) Postnatal CT image shows the gray matter–lined defect extending from the occipital horn of the lateral ventricle to the pial surface.

 


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  		Figure 7a.  Open-lip schizencephaly. (a) Axial SSFSE T2-weighted fetal MR image of patient 2 shows bilateral giant schizencephalic defects lined with gray matter. The thalami are not fused. (b) Axial SSFSE T2-weighted postnatal MR image shows the gray matter–lined defects. Note the presence of the falx, which makes the diagnosis of holoprosencephaly unlikely.

 


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  		Figure 7b.  Open-lip schizencephaly. (a) Axial SSFSE T2-weighted fetal MR image of patient 2 shows bilateral giant schizencephalic defects lined with gray matter. The thalami are not fused. (b) Axial SSFSE T2-weighted postnatal MR image shows the gray matter–lined defects. Note the presence of the falx, which makes the diagnosis of holoprosencephaly unlikely.

 


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  		Figure 8.  Normal facial characteristics. Sagittal SSFSE T2-weighted MR image of patient 2 shows a normal fetal profile, despite the large defects seen in this patient (Figs 2, 7). In the authors’ experience, schizencephaly is most often associated with normal facial characteristics.

 


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  		Figure 9a.  Characteristic imaging features. (a) Axial SSFSE T2-weighted fetal MR image shows a focal schizencephalic cleft extending from the pial surface to the ventricle (arrow). The cleft is lined with gray matter, which is seen as a low-signal-intensity line covering the edge of the remaining brain parenchyma (arrowheads). This finding allows differentiation of the defect from porencephaly. In addition, the CSP is absent (*). (b) Coronal SSFSE T2-weighted fetal MR image shows that the anterior horn of the lateral ventricle is tented, thus pointing to the defect.

 


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  		Figure 9b.  Characteristic imaging features. (a) Axial SSFSE T2-weighted fetal MR image shows a focal schizencephalic cleft extending from the pial surface to the ventricle (arrow). The cleft is lined with gray matter, which is seen as a low-signal-intensity line covering the edge of the remaining brain parenchyma (arrowheads). This finding allows differentiation of the defect from porencephaly. In addition, the CSP is absent (*). (b) Coronal SSFSE T2-weighted fetal MR image shows that the anterior horn of the lateral ventricle is tented, thus pointing to the defect.

 


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  		Figure 10.  Small schizencephalic defect. Axial SSFSE T2-weighted MR image of patient 5 shows a small, unilateral open-lip cleft extending to the underlying occipital horn. This defect was not identified at initial prenatal US (Fig 5a).

 


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  		Figure 11a.  Destructive lesions included in the differential diagnosis of schizencephaly. (a) Coronal SSFSE T2-weighted fetal MR image shows porencephaly. The hyperintense fluid collection is contained within the brain parenchyma, and a tiny rim of residual parenchymal tissue is present (arrow). Note that the collection is not lined with gray matter, unlike in schizencephaly. (b) Axial SSFSE T2-weighted MR image of a fetus with hydranencephaly shows large CSF collections and no significant residual parenchymal tissue. The falx is present, which allows differentiation of this condition from alobar holoprosencephaly.

 


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  		Figure 11b.  Destructive lesions included in the differential diagnosis of schizencephaly. (a) Coronal SSFSE T2-weighted fetal MR image shows porencephaly. The hyperintense fluid collection is contained within the brain parenchyma, and a tiny rim of residual parenchymal tissue is present (arrow). Note that the collection is not lined with gray matter, unlike in schizencephaly. (b) Axial SSFSE T2-weighted MR image of a fetus with hydranencephaly shows large CSF collections and no significant residual parenchymal tissue. The falx is present, which allows differentiation of this condition from alobar holoprosencephaly.

 


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  		Figure 12a.  Developmental lesions included in the differential diagnosis of schizencephaly. (a) Axial SSFSE T2-weighted fetal MR image shows an arachnoid cyst near the vertex. Unlike a schizencephalic defect, this lesion is in the extra-axial space. (b) Axial US image of another fetus shows the fused thalami (T) seen in holoprosencephaly, a mimic of schizencephaly. There appear to be bilateral wedge-shaped defects on this image; however, on images obtained in more superior planes, it was apparent that the "defects" communicated across the midline. (c) Coronal SSFSE T2-weighted fetal MR image shows a monoventricle, which confirms the diagnosis of holoprosencephaly. The black line represents the plane of the US image (b), which included part of the monoventricle bilaterally and gave the illusion of clefts. (d) Coronal SSFSE T2-weighted MR image of another fetus shows a large fluid collection in the midline. Although the collection is lined with gray matter (arrows), it is not continuous with the ventricles and is actually extra-axial. This patient has agenesis of the corpus callosum with a large interhemispheric cyst.

 


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  		Figure 12b.  Developmental lesions included in the differential diagnosis of schizencephaly. (a) Axial SSFSE T2-weighted fetal MR image shows an arachnoid cyst near the vertex. Unlike a schizencephalic defect, this lesion is in the extra-axial space. (b) Axial US image of another fetus shows the fused thalami (T) seen in holoprosencephaly, a mimic of schizencephaly. There appear to be bilateral wedge-shaped defects on this image; however, on images obtained in more superior planes, it was apparent that the "defects" communicated across the midline. (c) Coronal SSFSE T2-weighted fetal MR image shows a monoventricle, which confirms the diagnosis of holoprosencephaly. The black line represents the plane of the US image (b), which included part of the monoventricle bilaterally and gave the illusion of clefts. (d) Coronal SSFSE T2-weighted MR image of another fetus shows a large fluid collection in the midline. Although the collection is lined with gray matter (arrows), it is not continuous with the ventricles and is actually extra-axial. This patient has agenesis of the corpus callosum with a large interhemispheric cyst.

 


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  		Figure 12c.  Developmental lesions included in the differential diagnosis of schizencephaly. (a) Axial SSFSE T2-weighted fetal MR image shows an arachnoid cyst near the vertex. Unlike a schizencephalic defect, this lesion is in the extra-axial space. (b) Axial US image of another fetus shows the fused thalami (T) seen in holoprosencephaly, a mimic of schizencephaly. There appear to be bilateral wedge-shaped defects on this image; however, on images obtained in more superior planes, it was apparent that the "defects" communicated across the midline. (c) Coronal SSFSE T2-weighted fetal MR image shows a monoventricle, which confirms the diagnosis of holoprosencephaly. The black line represents the plane of the US image (b), which included part of the monoventricle bilaterally and gave the illusion of clefts. (d) Coronal SSFSE T2-weighted MR image of another fetus shows a large fluid collection in the midline. Although the collection is lined with gray matter (arrows), it is not continuous with the ventricles and is actually extra-axial. This patient has agenesis of the corpus callosum with a large interhemispheric cyst.

 


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  		Figure 12d.  Developmental lesions included in the differential diagnosis of schizencephaly. (a) Axial SSFSE T2-weighted fetal MR image shows an arachnoid cyst near the vertex. Unlike a schizencephalic defect, this lesion is in the extra-axial space. (b) Axial US image of another fetus shows the fused thalami (T) seen in holoprosencephaly, a mimic of schizencephaly. There appear to be bilateral wedge-shaped defects on this image; however, on images obtained in more superior planes, it was apparent that the "defects" communicated across the midline. (c) Coronal SSFSE T2-weighted fetal MR image shows a monoventricle, which confirms the diagnosis of holoprosencephaly. The black line represents the plane of the US image (b), which included part of the monoventricle bilaterally and gave the illusion of clefts. (d) Coronal SSFSE T2-weighted MR image of another fetus shows a large fluid collection in the midline. Although the collection is lined with gray matter (arrows), it is not continuous with the ventricles and is actually extra-axial. This patient has agenesis of the corpus callosum with a large interhemispheric cyst.

 




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