Imaging of Congenital Imaging of Congenital Brain MalformationsBrain Malformations

Moment of embryology

Neurulation Neurulation

Ventral induction

Man

tlM

antl

ee

ProliferationProliferation

MigrationMigration

OrganizationOrganization

Myelination PNS CNS

Normal myelinationAt birth 1 year6 month 2 years

CephalocelesCephalocelesHerniation of intracranial contents through a

congenital defect in the dura and skull- Usually located at the midline.

Occipital Meningoencephalocele

Parietal Meningoencephalocele

Atretic occipital cephalocele

Chiari malformation type I

Basilar invagination

Posterior fossa decompression

Chiari malformation type III

Prosencephalon

Mesencephalon

Rhomboencephalon

Classification of holoprosencephaly

Classification of holoprosencephaly

Septo-optic Dysplasia

DWM DWV Persistent Blake’s pouch

Mega cisterna magna

Anterior membranous area anomaly Posterior membranous area anomaly

Retro-cerebellar cyst

Vermis Hypo-plasticRotated upwards

Hypo-plastic No or mild hypoplasia

No or mild hypoplasia

4th ventricle Markedly dilated Dilated Dilated Normal

Posterior fossa Expanded Normal size Normal size Normal size

hydrocephalus 75 % of cases 25% of cases Present No

Dandy-Walker Malformation Dandy-Walker Malformation

Dandy-Walker Variant

Mega Cistern Magna

Posterior Fossa Arachnoid Cyst

Corpus callosum genesis

Corpus callosum develpment

Corpus Callosum genesis• Genu body splenium rostrum

Corpus Callosum Agenesis

Corpus Callosum Agenesis Absent cingulate gyrus

High riding 3rd ventricle

Parallel lateral ventricles

Colpocephaly

frontal horns small & pointed

Radiating medial surface gyri

Partial corpus Callosum Agenesis

Corpus Callosum Agenesis Interhemispheric cyst

Corpus Callosum Agenesis Pericallosal lipoma

Focal cortical dysplasia

Focal cortical dysplasia

Focal cortical dyspalsia

Tuberous sclerosis

• Cortical tubers.• White matte lesions.• Subependymal nodules.• SGCA.

Ganglioglioma

DNET

Type 1 lissencephaly(agyria / pachygyria complex)

Type 2 (cobblestone) lissencephaly

Heterotopia

Heterotopias

• Normal neurons at abnormal sites• Result from arrested neuronal migration from

periventricular germinal zone to the cortex.• Heterotopias are isointense to normal gray

matter in all pulse sequences and do not enhance on administration of IV contrast.

Hetertopia

• Isointense to grey matter on all pulse sequences

No enhancement. No associated mass effect.

Band hetertopia

Sucortical curvilinear nodular hetertopia

Subcortical focal nodular heterotopia

Subependymal diffuse nodular heterotopia

subependymal focal nodular hetertopia

Polymicrogyria

Polymicrogyria

Schizencephaly

• CSF cleft , lined by grey matter, between the ependymal surface of the ventricle to the pial surface of the cerebral hemisphere.

Vascular theory of Schizencephaly

Myelination disorders

Dys-myelination Vs hypo-myelination

Dys-myelination

Hypo-myelination

Delayed myelination Vs hypomyelination

• Repeat MRI after 6 months.• Delayed myelination myelination progression.• Hypomyelination no myelination progression.• DD in these 2 conditions is quite different.

Delayed myelination

• Delayed myelination is a non specific finding associated with global developmental delay.

Causes:• Chromosomal abnormalities (e.g. trisomy 21).• Metabolic disorders (e.g. phenylketonuria).• Acquired causes (e.g. HIE).

Special features

DD of leukodystrophies