MIDLINE ANOMALIES OF THE BRAIN

1. Disorders of Closure.
• Facial clefts
• Craniorachischisis
• Corpus Callosum:
• Corpus Callosum Agenesis.
• Lipoma.
• Arnold - Chiari Malformation
• Dandy-Walker Malformation
2. Disorders of Diverticulation.
• Holoprosencephaly:
• Alobar
• Semilobar
• Lobar
3. Absent Cavum Septum Pellucidum (3-6).
• May be normal after 38 weeks GA.
• Agenesis of the corpus callosum.
• Holoprosencephaly.
• Septo-optic dysplasia.
• Schizencephaly.
• Encephaloceles.
• Heterotopic gray matter.

Absent cavuum septum pellucidum in lobar holoprosencephaly

4. Enlarged Cavum Septum Pellucidum (>5 mm).
• Bronshtein and Weiner (7) suggest a possible correlation with chromosomal aberrations and other malformations.
• Vergani and associates (8), in a later study found all fetuses with a large cavum to be normal.

REFERENCES

1. DeMyer W. Classification of cerebral malformations. Birth Defects Orig Artic Ser 1971;7:78.
2. Fitz CR. Midline anomalies of the brain and spine. Radiol Clin North Am 1982;20:95.
3. Falco P, Gabrielli A, Visentin A et.al. Transabdominal sonography of the cavum septum pellucidum in normal fetuses in the second and third trimester of pregnancy. Ultrasound Obstet Gynecol 2000;16:549-553.
4. Jou HJ, Shyu MK, Chen SM et.al. Ultrasound measurements of the fetal cavum septi pellucidi. Ultrasound Obstet Gynecol 1998;12:419-421.
5. Pilu G, Sandri F, Cerisoli M et.al. Sonographic findings in septo-optic dysplasia in the fetus and newborn infant. Am J Perinatal 1990;7:337-340.
6. Pilu G, Falco P, Perola A et.al. Differential diagnosis and outcome of fetal intracranial hypoechoic lesions report of 21 cases. Ultrasound Obstet Gynecol 1997;9:229-234.
7. Bronshtein M, Weiner Z. Prenatal diagnosis of dilated cava septi pellucidi and vergae: associated anomalies, differential diagnosis, and pregnancy outcome. Obstet Gynecol 1992;80:838-842.
8. Vergani P, Locatelli A, Piccoli MG et.al. Ultrasonographic differential diagnosis of fetal interhemispheric cysts. Am J Obstet Gynecol 1999;180:423-428.