Corpus callosal Hypoplasia

MRI Brain Axial T2w sections shows inter hemispheric fissure is not a straight mid line with inter digitating gyri.

Sagittal T1w mid line section show a relatively smaller thickness body portion of Corpus callosal stripe. All portions of corpus callosum visualized. No any particular portion missing.
Normal anterior lobe of pituitary.

Imaging diagnosis: Hypoplasia of Corpus callosum.

Hypoplasia refers to a thin but morphologically intact corpus callosum, not a normal variant of development but rather an abnormality of cerebral development.
Associated with development delay, autism, congnitive disorders and Hereditary Spasitc Paraplegia. 

Corpus callosal Agenesis

Agenesis of CC may be complete (all segment of CC absent) or Partial (usually body remains rest of the CC may be absent)
Imaging findings in complete CC Agenesis:
1. Parallel non converging widely separated lateral ventricles on axial sections,the most striking feature.
2. Occipital horn dilated – Colpocephaly.
3. Pointed or trident shaped frontal horns on coronal sections.
4. Non visualisation of normal stripe of CC on mid sagittal section, gyri and sulci directly radiating from roof of third ventricle.
5. High riding third ventricle.
6. Absent cingulate gyrus on sagittal section which is normally seen parallel and cranial to CC.
7. Vertically originated hippocampi with key hole appearance of temporal horns on coronal sections.
8. Probst bundles, the abnormal longitudinally orientated band of white matter track medial to lateral ventricles seen on coronal sections.

Related posts :
corpus-callosal-lipoma
Corpus callosal agenesis with heterotrophia
corpus-callosal-agenesis-with-lipoma
Corpus-callosal-complete-agenesis
interhemispheric-cyst-without-copus callosal anomaly
Corpus-callosal-destruction
Corpus-callosal-partial-agenesis

Corpus callosal Lipoma

Axial non contrast CT study brain shows a fat density along inter hemispheric fissure.
The mid line sagittal T1w image show a curvilinear type of lipoma along corpus callosum.
Role of MRI in this case is to rule out any associated Corpus callosal anamoly.
Corpus callosum is normal.

Related post :
Corpus-callosal-agenesis-with-lipoma
Meckel's Cave Lipoma
Lipoma at incisura

Intracranial lipoma 


Syn : Lipomatous hamartomas, as normally fat not present in CNS.
A congenital malformation , not true neoplasm.
Contributes < 0.5% of all intracranial tumors.
A focal fat density (dark 'z' black) on CT or fat signal intensity (white on T1w image) and is often out standing in the background of adjacent normal grayish brain parenchyma.
Noted as an isolated incidental finding or as part of an associated anomalies. Most common anomaly associated is Corpus callosal agenesis or dysgenesis.

Most common location is supra tentorium ~80%. In that most common location is mid line along corpus callosum ~ 50%, Suprasellar cistern attached to infundibulum, hypothalamus ~ 20%,  Pineal region ~15%. Meckel's cave and lateral fissures are rare locations.
Infra tentorium contributes remaining 20%, in that common locations are Cp angles, jugular foramen and foramen magnum.

Two types of intracranial lipoma:
1. Curvilinear type is a thin stripe along CC.
2. Tubulonodular type is a bulky nodular mass, frequently show dense nodular calcifications, and often associated with Corpus callosal or adjacent parenchymal anomalies.

Interhemispheric cyst without corpus callosal agenesis are usually Arachnoid

A 60 yo female with giddiness since 1 month.
Here is her MRI Brain; Coronal T2, Axial FLAIR, Coronal Post contrast T1, Diffusion and sagittal T1w images.

This MRI study of Brain shows:
A cyst along interhemispheric fissure on left side of falx, in left para sagittal parietal region, isointense to Csf, no restricted diffusion on diffusion. No adjacent parenchymal Gliosis or volume loss. Non enhancing on post contrast T1.
No associated corpus callosal malformation agenesis or dysgenesis on mid sagittal T1. Corpus callosum is compressed.
Cyst is not communicating with ventricular system. Left lateral ventricle compressed.

Imaging wise Possible DDs: Arachnoid cyst, Epithelial cyst.


In an elderly patient inter hemispheric cyst without associated corpus callosal agenesis are usually Arachnoid cysts. Whereas inter hemispheric cyst associated with agenesis of the corpus callosum, which will be clearly demonstrated on magnetic resonance imaging  are usually non arachnoid cysts.
Reference : 
1. Interhemispheric arachnoid cyst in the elderly: case report and review of the literature; Fumiyuki Yamasaki M.D,
2. A case of symptomatic interhemispheric arachnoid cyst in the elderly by M Tomabechi, K Takano, N Suzuki, G Daita.

Porencephalic cyst ruled out as there is no adjacent parenchymal Gliosis, volume loss or communication with ventricular system.
Epidermoid cyst ruled out as there is no restricted diffusion on diffusion.

Corpus callosal Agenesis with Heterotrophia

Non contrast CT Brain

This CT study of Brain shows:
Corpus callosal Agenesis evident by widely separated non converging lateral ventricles.
An associated heterotrophic grey matter seen as a mass iso dense to cortical grey matter and deep grey nuclei in right frontal lobe, a congenital malformation characterized by focal clumps of grey matter at abnormal location.


HETEROTROPHIA

A congenital disorder of abnormal neuronal migration.
Gray matter stuck at wrong place.

Can be inherited or acquired (from maternal trauma, infection or toxin)

Normally sub ependymal germinal zone proliferates and form neuroblasts and glial cells which then migrates outwards towards cerebral convexity forming an outer cortical grey matter and inner white matter. Any interruption or arrest in the normal course of this neuronal migration leaves heterotrophic neuronal deposits. These being gray matter deposits follow same density and signal intensity as that of cortical gray matter, non enhancing.

Types:
Sub ependymal nodular heterotrophia – a focal or multi focal subependymal nodules.
Band heterotrophia – alternate band of gray and white matter , ‘ double cortex’.

Clinical presentation :
Seizures is most common, delayed milestones.

DDs:
Closest differential is subependymal nodules of Tuberous sclerosis which often shows an associated calcification.

Treatment:
Surgery reserved for intractable Sz.
Resect small accessible Epileptogenic nodules.
Corpus Callosotomy if bilateral or diffuse unresectable lesions.

Corpus callosal Agenesis with Lipoma

Non contrast CT Brain, MRI Brain Axial T1 and Sagittal T1w images

Findings are non converging, widely separated parallel lateral ventricles due to Corpus Callosal partial Agenesis better seen on MRI sagittal T1w images as splenium portion of CC is not visualized (white arrow)
There is an associated inter hemispheric lipoma with curvilinear calcification.

Related post :
Corpus-callosal-lipoma 
Meckel's Cave lipoma
Lipoma at incisura

Intracranial lipoma 

Syn : Lipomatous hamartomas, as normally fat not present in CNS.
A congenital malformation , not a true neoplasm.
Contributes < 0.5% of all intracranial tumors.

A focal fat density (dark 'z' black) on CT or fat signal intensity (white on T1w image) and is often out standing in the background of adjacent normal dark brain parenchyma on T1w images.
Noted as an isolated incidental finding or associated with other anomalies as a part of syndrome. Most common anomaly associated is Corpus callosal Agenesis / Dysgenesis.

Most common location is supra tentorium ~80%. In that most common location is mid line along corpus callosum ~ 50%, Suprasellar cistern attached to infundibulum, hypothalamus ~ 20%,  Pineal region ~15%. Meckel's cave and lateral fissures are rare locations.
Infra tentorium contributes remaining 20%, in that common locations are Cp angles, jugular foramen and foramen magnum.

Two types of intracranial lipoma:
1. Curvilinear type is a thin stripe along CC.
2. Tubulonodular type is a bulky nodular mass, frequently show dense nodular calcifications, and often associated with Corpus callosal or adjacent parenchymal anomalies.

Corpus callosal Destruction

A 35 y o female with seizures. 

Here is her CT Brain, MRI Brain Axial T1w, T2w, FLAIR, Diffusion, Axial Post contrast T1w and Sagittal T1w images. 

This CT and MRI Brain shows destruction of corpus callosum, Gliosis involving right superior frontal and cingulate gyrus with dense dystrophic calcification on CT, a right temporo parietal Porencephalic Cyst.

Appears to be secondary to Perinatal ischemic brain insult.

Discussion:

Unlikely to be the routine congenital malformation of corpus callosum like agenesis or dysgenesis as there is no complete non visualisation of corpus callsum instead a thin stripe of corpus callosum is seen on sagittal sections. An associated well circumscribed clear Csf signal intensity cystic lesion in the region of right lateral ventricle, communicating with the ventricular system is a por encephalic cyst.  Cysts associated with corpus callosal agenesis are in mid line along inter hemispheric fissure. Gliosis with dense dystrophic calcification involving right superior frontal gyrus and cingulate gyrus better seen on CT. Fibrotic bands extending from right thalamus going towards septum pellucidum seen on sagittal sections. 

Corpus callosal partial Agenesis

Agenesis of CC may be complete (all segment of CC absent) or Partial (usually body remains rest of the CC may be absent as in this case)

MRI Mild Sagittal sections are must showing non visualisation of part of CC.
Finding may not be very obvious on axial sections which may show mild relatively wide and separated lateral ventricles in corresponding region.

An associated T1 bright stripe of Lipoma noted in this case.

Typical finding of complete agenesis of CC like Occipital horn dilated – Colpocephaly, Pointed or trident shaped frontal horns, High riding third ventricle, Vertically originated hippocampi with key hole appearance of temporal horns, Probst bundles may not be seen in partial agenesis. 

Corpus Callosal Complete Agenesis

CT Brain axial sections, MRI Brain Sagittal T1 and Coronal T1w images

Mid Sagittal T1w image of normal for comparison

Imaging findings in complete CC Agenesis:  
1. Parallel non converging widely separated lateral ventricles on axial sections,the most striking feature.

2. Occipital horn dilated – Colpocephaly.

3. Pointed or trident shaped frontal horns.

4. Non visualisation of normal stripe of CC on mid sagittal sections, gyri and sulci directly radiating from roof of third ventricle. 

5. High riding third ventricle. 

6. Absent cingulate gyrus which is normally seen parallel and cranial to CC.

7. Vertically originated hippocampi with key hole appearance of temporal horns on coronal sections.

8. Probst bundles, the abnormal longitudinally orientated band of white matter track medial to lateral ventricles seen on coronal sections.

9. May seen an associated lipoma or inter hemispheric cyst if any.

Agenesis of CC may be complete (all segment of CC absent) or Partial (usually body remains rest of the CC may be absent)