imaging in developmental malformations of the brain
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Imaging in Developmental Malformations of the Brain
Presenter :Dr.Chakradhar
Over view1.Introduction2.Normal development of Brain3.Classification of malformations4.Imaging features of anomalies5.conclusion
Imaging in developmental Malformations of the brain
Introduction
Congenital anomalies of the brain Extremely complex Best studied by correlating with embryological
development.
Imaging in developmental Malformations of the brain
NORMAL BRAIN DEVELOPMENT
MYELINATIONDORSAL INDUCTIONFormation of neural
tube
VENTRAL INDUCTIONFormation of vesicles
and SegmentationMYGRATION, andPROLIFERATION
a.Primary Neurulation
b.Secondary neurulation
Imaging in Developmental malformations of the brain
Stages of brain development
Imaging in Developmental malformations of the brain
Three phases: Neurulation, Canalization, Retrogressive differentiation
Stage 1: Dorsal Induction: Formation and closure of the neural tube
Occurs at 3-5 weeks
Dorsal induction defects:
.
Imaging in Developmental malformations of the brain
Stages of brain development
Neural tube defects -Anencephaly, -Cephalocele, - Chiari malformations and -Spinal dysraphic disorders
Stage 2: Ventral Induction: Formation of the brain segments and face
Occurs at 5-10 weeks of gestation
Stages of brain developmentImaging in Developmental malformations of the brain
Three vesiclesProsencephalon - cerebral hemispheres/thalamus, Mesencephalon- midbrain and Rombencephalon- cerebellum/brain stem
Ventral induction disorders:
Imaging in Developmental malformations of the brain
Stages of brain development
Holoprosencephalies, Dandy Walker malformation, Cerebellar hypoplasia/dysplasia Joubert syndrome, Rhombencephalosynapsis, Septo -optic dysplasia, and Facial anomalies.
Stage 3: Migration and Differentiation Occurs at 2-5 months of gestation
.
Imaging in Developmental malformations of the brain
Stages of brain development
Neuronal migration from germinal matrix to the surface resulting in Cortical organization
Migration Disorders:
Imaging in Developmental malformations of the brain
Stages of brain development
Heterotopias, Agyria-pachygyria, Polymicrogyria, Lissencephaly, Schzencephaly, Corpus callosal agenesis, Lhermitte-Duclos disease
Differentiation and proliferation disorders:
Imaging in Developmental malformations of the brain
Stages of brain development
Aqueductal stenosis, Arachnoid cyst, Megalencephaly, Micoencephaly, Neurocutaneous syndrome (phakomatoses)Congenital vascular malformation, andCongenital neoplasms
Stage 4: MyelinationBegins at 6 months of gestation, Matures by 3 years.
Imaging in Developmental malformations of the brain
Stages of brain development
Progresses from Caudal to Cephalic, Dorsal to Ventral, and Central to Peripheral
Disorders of Myelination Dysmyelinating diseases, Leukodystrophies.
DISORDERS OF NEURAL TUBE FORMATION
DISORDERS OF SEGMENTATION
DISORDERS OF MYGRATION and
CORTICAL ORGANISATION
DISORDERS OF MYELINATION
a.Anencephaly
b.Cephaloceles
c.Chiari Malformations
a.Holoprosencephaly1.Alobar
2.Semilobar 3.Lobar
b.Corpus callosal agenesis
c.Dandy Walker malformations
a.Hetrotropias
b.Lissencephaly, Schizencephaly
Classification of congenital malformation of brain
a.Leukodystrophies
b.Dysmyelinating Disorders
Imaging in Developmental malformations of the brain
Neural Tube Defects
Imaging in Developmental malformations of the brain
Anencephaly Neural Tube Defects
Imaging in Developmental malformations of the brain
complete or partial absence of the cerebral structures, cranial vault and skull base.
It results from failure of closure of the cephalic portion of the neural tube
CephalocelesHerniation of intra cranial structures through
congenital defects in Dura and skull
Cephaloceles
MeningoencephalocystoceleMeningoencephaloceleMeningocele
MeningesMeninges Meninges
Neural tissue Neural tissue
Ventricles
Neural Tube DefectsImaging in Developmental malformations of the brain
Neural Tube Defects
Encephalocele
Fronto Nasal Encephalocele Occipital Encephalocele
Imaging in Developmental malformations of the brain
Neural Tube Defects
Herniation of brain and Meninges through a defect in the skull.It is typically covered by skin (closed defect) or a Thin layer of epithelium (open defect).
Fronoto Nasal, Naso Orbital Encephalocele
Nasal Glioma(D/d for encephaloele)
Imaging in Developmental malformations of the brain
Neural Tube Defects
Type of Chiari malformation
Imaging features(core) Associated findings
Type 1 (Tonsillar Ectopia)
Elongated cerebellar tonsils with herniation into cervical canal
Syringohydromyelia(30-60%)
Type 2 (Arnold Chiari)
Herniation of vermis ,tonsils, medulla 1.Small and shallow posterior fossa2.Myelomeningocele (nearly 100%)3.Upward herniation of cerebellar hemispheres 4.Corpus callosal dysgenesis, heterotopias, polymicrogyria
Type 3 Type 2 + occiputal encephalocele
Type 4 Cerebellar Aplasia/Sever Hypoplasia
The chiari malformations
Imaging in Developmental malformations of the brain
Neural Tube Defects
Chiari I Malformation
Imaging in Developmental malformations of the brain
Neural Tube Defects
Level below the Foramen Magnum First Decade: 6mm Second /Third decade: 5mm Fourth-Eight Decade:4mm and Nienth Decade:3mm
Chiari II Malformation
Imaging in Developmental malformations of the brain
Neural Tube Defects
Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation
Holoprosencephaly
Disorders of Diverticulation and Segmentation
Cerebellum and brain stem are relatively normal
Imaging in Developmental malformations of the brain
Developing Forebrain (prosencephalon) fails to divide into hemispheres and lobes.
Normal brain Alobar Holoprosencephaly
semilobar Holoprosencephaly Lobar Holoprosencephaly
Types of Holoprosencephaly
Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation
Alobar Holoposencephaly
Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation
• Single cresent shaped ventricle • No Separation of the cerebral hemispheres• Fused thalami and basal ganglia• Absence of septum pellucidum, corpus callosum, falx cerebri, and interhemispheric fissure
Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation
Semilobar holoprosencephaly
• Interhemispheric fissure is formed posteriorly•Rudimentary occipital and temporal horns•Thalami and basal ganglia are partially separated•Septum pellucidum is absent• callosal splenium may be formed
Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation
Lobar holoprosencephaly
• Ventral portions of the frontal lobes remains fused• Rudimentary frontal horns are formed • Septum Pellucidum is absent• Thalami and basal ganglia well separated
Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation
Septo optic Dysplasia (de Morsier syndrome)
• Milder form of lobar holoprosencephaly• Hypoplastic optic nerves, optic chiasma, • Absent septum pellucidum•Squared frontal horns
Associated hypoplasia of Hypothalamic-Pituitary axis seen in 2/3rd cases
Imaging in Developmental malformations of the brainDisorders of Diverticulation and Segmentation
Corpus Callosum Agenesis
Corpus callosal development starts at 12 weeks , and completes by 20 weeks
Formation is from anterior to posterior direction, Starts with Genu- Body-Splenium. The rostrum is last to develop
Corpus Callosum Agenesis
Complete agenesis Partial agenesis
Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation
Complete callosal agenesis
•Entire corpus callosum, cingulate gyrus and sulcus are absent•Widely separated, parallel and non-converging lateral ventricles.• Colpocephaly (dilated occipital horns) •Frontal horns are small and pointed
Complete corpus callosal agenesiscolpocephaly
Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation
Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segemtation
Partial callosal agenesis
•Splenium and rostrum absent• Genu and body present
Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation
Associated anomalies•Migration disorders (heterotopias, lissencephaly, schizencephaly)• Chiari II malformation• Dandy-Walker malformation• Holoprosencephaly• Corpus callosal lipoma
Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation of Posterior fossa
Dandy walker spectrum
Dandy Walker syndrome
Dandy Walker variant
Mega Cysterna Magna
Imaging in Developmental malformations of the brainDisorders of Diverticulation and Segmentation of Posterior fossa
Imaging in Developmental malformations of the brainDisorders of Diverticulation and Segmentation of Posterior fossa
Joubert’s Syndrome (Congenital Vermian Hypoplasia)
• Vermian dysgenesis•Enlarged superior cerebellar peduncles and • High riding fourth ventricle.
Imaging in Developmental malformations of the brain
Associated anomalies• Occipital encephalocele (30%),• Callosal dysgenesis,• Cortical dysplasia,• Hypothalamic hamartoma, and• Ocular, hepatic & renal diseases.
Disorders of Diverticulation and Segmentation of Posterior fossa
Classified into two groups:
Imaging in Developmental malformations of the brainDisorders of Diverticulation and Segmentation of Posterior fossa
Pontocerebellar hypoplasia (PCH).• Combined hypoplasia of both the cerebellum and the pons•These are primarily genetic disorders
• Hypoplastic Brain stem and cerebellum that is close to the tentorium• Cerebellar hemisphares are wing like, appear to float in posterior fossa.
Imaging in Developmental malformations of the brainDisorders of Diverticulation and Segmentation of Posterior fossa
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Imaging in Developmental malformations of the brainDisorders of Diverticulation and Segmentation of Posterior fossa
Differentials of pontocerebellar hypoplasia
CDG syndromes-(disialotransferrin) will be elevated in CDGDandy-Walker syndrome - Normal PonsDandy-Walker variant -Normal Pons
Disorders of Migration
Imaging in Developmental malformations of the brain
Ectopic Migration
Cobble stone-Lissencephaly(type 2)
Over Migration
Classic Lissencephaly (type1)
Under Migration
Migration Disorders
Band Heterotropia
Subcortical
Subependymal
Heterotrpia
Imaging in Developmental malformations of the brain
Disorders of Migration
Imaging in Developmental malformations of the brain
Disorders of Migration
Lissencephaly (Agyria-Pachygyria):
Refers to “smooth brain” with absent or poor sulcation.
Types: Complete (agyria) Incomplete (pachygyria).
.
Imaging in Developmental malformations of the brain
Disorders of Migration
• Thickened cortex with flat broad gyri•Smooth gray-white matter Interface• Colpocephaly Oblique and shallow • Sylvian fissures- figure eight
Type I (classical) Lissencephaly
Associated with Miller-Dieker syndrome
Type II(Cobblestone) Lissencephaly
Imaging in Developmental malformations of the brain
Disorders of Migration
• Thickened cortex • Polymicrogyric appearance. • Hypomyelination of underlying white matter
Associated with Fukuyama congenital muscular dystrophy,Walker-Warburg syndrome and muscle-eye-brain syndrome
Two types: Nodular type(common), Band/laminar type (uncommon)
Imaging in Developmental malformations of the brain
Disorders of Migration
HeterotopiasPresence of normal neurons at abnormal sites
Best appreciated on medium tau inversion recovery sequences
Nodular type:
Imaging in Developmental malformations of the brain
Disorders of Migration
• A layer of neurons interposed between the ventricle and cortex•Overlying cortex has pachygyria or polymicrogyria
Band or laminar type
Disorders of Cortical organisation
Imaging in Developmental malformations of the brain
Non lissencephalic Cortical Dysplasia
Disorders of Cortical organisationImaging in Developmental malformations of the brain
Disorders of Cortical organisation
Polymicrogyria
• Thickened cortex •Irregular, bumpy gyral pattern• Irregular gray-white matter junction• Underlying white matter signal changes
Pachygyria
Imaging in Developmental malformations of the brain
Disorders of Cortical organisation
•Thickened and flattened cortex• Blurred gray-white matter Junction• Underlying white matter signal changes
Schizencephaly
Imaging in Developmental malformations of the brain
Disorders of Cortical organisation
Cleft lined by Heterotopic gray matter extends from the ventricular (ependyma) to the periphery (pial surface) of the brain, traversing through the white matter.
Two types: Closed lip (type I) Open lip (type II)
Closed lip (type I) schizencephaly
Openlip (type2) schizencephaly
Imaging in Developmental malformations of the brain
Disorders of Cortical organisation
Porencephalic cyst resembles schizencephaly but CSF space is lined by gliotic white matter, in contrast to gray matter as in Schizencephaly
Porencephalic cyst
Imaging in Developmental malformations of the brain
Disorders of Cortical organisation
Anomalies Associated with Schizencephaly : Heterotopias, Septo-optic dysplasia,Absence of septum pellucidum Callosal dysgenesis
Imaging in Developmental malformations of the brain
Disorders of Cortical organisation
Hemimegalencephaly Hamartomatous overgrowth of a part or all of one
cerebral hemisphere
Imaging in Developmental malformations of the brain
Disorders of Cortical organisation
Associated with :• Epidermal nevus syndrome, • Klippel-Trenaunay–Weber syndrome, • Neurofibromatosis type 1
• Linear Nevus Sebaceous Syndrome(LNSS)
Imaging in Developmental malformations of the brain
Disorders of Cortical organisation
Conclusion• Variety of congenital anomalies of brain of
brain coexist • Clinical Presentation of various anomalies is
more or less same• Imaging plays an important role in diagnosing
them
Thank you
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