By: Nour-Eldin Mohammed

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ByNour-Eldin Mohammed
Neuroradiology Congenital Malformation of CNS
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Callosal Dysgenesis

• Definitions
• One or all segments of CC absent
• (if partial, body remains)

• CC segments front to back
• Lamina rostralis (unmyelinated)
• Rostrum (myelinated)
• Genu
• Body
• Splenium

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Callosal Dysgenesis

• General Features
• Axial Parallel lateral ventricles
• Coronal "Trident" anterior horns resemble
  "viking helmet" or "moose head
• Location Midline anomaly
• Size CC remnants vary in size, shape , Remnant
  may be paper thin or bulbous

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Callosal Dysgenesis
Radially arrayed gyri "point to" 3rd ventricle
Absent Cingulate Gyrus
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Callosal Dysgenesis
Lateral ventricles are key to diagnosis
Parallel (non-converging) Widely separated
Occipital horns often dilated (colpocephaly)
Pointed frontal horns
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Callosal Dysgenesis

• Coronal T2WI MR
• shows agenesis of the corpus
• Callosum
• trident shaped lateral ventricles
• vertical hippocampi (open arrow),
• enlarged, "keyhole" shaped
• temporal horns and Probst
• bundles (curved arrow).

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Callosal Dysgenesis
Axial NECT with widened "windows" shows
colpocephaly, calcified (arrow) midline lipoma
that extends through choroid fissures into
lateral ventricles (open arrows).
Axial TlWI MR shows parallel ventricles,
colpocephaly, and a midline lipoma. Note lipoma
(arrow) protruding into the lateral ventricles.
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Callosal Dysgenesis

• Coronal T2WI MR in fetus shows trident shaped
  lateral
• ventricles, agenesis of Cc
• "Probst bundle" (curved arrow)
• vertical hippocampus (arrow).

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Differential Diagnosis of Callosal Dysgenesis
Partial Absence of Callosal Dysgenesis
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Differential Diagnosis of Callosal Dysgenesis
Destruction of CC
Surgery (callosotomy),trauma
(Acquired interhemispheric disconnection
syndrome) Hypoxic ischemic encephalopathy
(HIE), infarcts Metabolic
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Differential Diagnosis of Callosal Dysgenesis
Stretched Corpus Callosum (e.g. Hydrocephalus)
Thinned CC but all parts present Severe
hydrocephalus often present
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Lipoma

• Definitions
• Mass of mature non-neoplastic adipose tissue
• CNS lipomas are congenital malformations, not
  true
• neoplasm

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Lipoma

• General Features
• Best diagnostic clue Well-delineated lobulated
  extra-axial mass with fat attenuation/intensity
• Location Midline location common
• 80 supratentorial
• 40-50 interhemispheric fissure (over corpus
  callosum may extend into lateral ventricles,
  choroid plexus)
• 15-20 suprasellar (attached to infundibulum,
  hypothalamus)
• 10-15 pineal region (usually attached to tectum)
• 20 infratentorial
• Cerebellopontine angle (may extend into lAC,
  vestibule)
• Uncommon Jugular foramen, foramen magnum

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Lipoma
Sagittal Tl WI MR
Sagittal Tl WI MR with fat-saturation
(a small interhemispheric lipoma (arrows) above
the corpus callosum, found incidentally at MR
imaging in this patient with headache.
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Lipoma
Sagittal TlWI MR shows a well-circumscribed high
signal lesion in the pineal region (arrow).The
patient was asymptomatic.
Axial gross pathology shows a quadrigeminal
lipoma (arrow)
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Vielen Dank