PEDIATRIC NEUROLOGICAL DISEASES: CEREBRAL

ANOMALIES

Basic diagnostic modality• MRI• US

CT has been left away because of its radiation exposure & MRI is superior in imaging the specific pediatric problem

Main group CNS malformations

• Dysgeneses• Dysraphias• Sulcation migration disorders• Brain volume disorders• Hydrocephalus• Phakomatoses

Dysgeneses• Proencephalic vesicles’ defective

development• Non-disturbed neural tube closure• e.g.: Acephalia, holoprosencephaly

Holoprocencephaly

Dysraphias• Defective neural tube closure

– Cranial dysraphias– Rhombocerebellar dysraphias

Dysraphias• Cranial dysraphias

– Anencephaly• Rhombocerebellar dysraphias

– Meningocele– Cerebellar hypoplasia– Dandy-Walker syndrome– Arnold-Chiari malformation– Aquaduct stenosis

Encephalocele• Meningocele

CSF• Encephalocystomeningocele

Cystic rudiment ventricle + brain parenchyma + CSF

• EncephaloceleBrain parenchyma

• Encephalocystocelea ventricle-connected CSF cavity + brain parenchyma

Meningocele Encephalocystomeningocele

Encephalocele Encephalocystocele

Arnold-Chiari Malformation[Classification Based on deformity severities]• Type I

– Herniation of cerebellar tonsil & inferior cerebellum through foramen magnum

– Syringomyelia• Type II• Type III

– Type II + occipital encephalocele

Arnold-Chiari Malformation• Type I

– Herniation of cerebellar tonsil & inferior cerebellum through foramen magnum

– Syringomyelia

Arnold-Chiari Malformation[Based on deformity severities]• Type II

Deformation of the brain stem– Herniation of tonsils & inferior vermis through foramen

magnum– MO elongated & overlaps the upper segments of

cervical spinal– Meningomyelocele, Hydrocephalus– Expanded spinal canal, enlarged & oval-formed

foramen magnum– 4th ventricle at the level of foramen magnum– Hypoplasia of the falx & tentorium– Cerebelum is displaced supratentorial between the

posterior horns of lateral ventricle

Arnold-Chiari Malformation type II

Dandy-Walker SyndromeTriad:– Inferior vermis aplasia/hypoplasia

& displacement of the hypoplastic cerebellum (laterally)

– 4th ventricle cystic transformation– Hydrocephalus

Dandy walker malformation

• Frequent cause of the congenital hydrocephalus

• CT / MRI view: the first 3 ventricles are distended while the 4th ventricle remains normal

• Craniosynostoses

Congenital Aqueduct Stenosis

PhakomatosesDysplasias with disturbed cellular migrations 1. Sturge-Weber syndrome

– Encephalotrigeminal angiomatosis– CT/ MRI : Calcification on cortical regions;

leptomeningeal angiomatosis of the temporal, parietal, occipital; atrophy

– CT/ MRI + contrast medium: diffuse enhancement at the margins of calcium deposits

Sturge Weber syndrome

PhakomatosesDysplasias with disturbed cellular migrations 2. Neurofibromatosis3. Tuberous Sclerosis4. Hippel-Lindau syndrome

Migration• Schizencephaly• Lissencephaly / Agyria & Pachygyria• Polymicrogyria

Schizencephaly• Slit-shaped defects along the

fissures (sylvian)• Stretch from ventricular wall

up to cerebral membranes of cortex

• Limiting gray matters with abnormal stratification

• Aplasia of the pellucid septum

Lissencephaly (Agyria)

• Telencephalon remains in a primitive form wo/ developing convolutions

• Failure to form sulci• Abnormal development of the cerebral fissure• Widening of the cortex

Pachygyria

Hydrocephalus• Congenital hydrocephalus, the most

common frequent pediatric neurological condition (0.3% of all newborn)

• Imbalance between the production & absorption Increase amount of CSF (N: 150 ml) ICP & brain parenchyma pressure gradient raised

CSF Physiology• CSF Production: 80-90% by choroid plexus.

Daily secretion rate of 500 ml.• CSF Absorption: Arachnoid granulations above

the cerebral hemispheres• CSF Flow: Lateral ventricle Foramen of

Monroe 3rd ventricle Sylvian aqueduct 4th ventricle Foramen of Magendie & Foramina of Luschka cerebello-medullary cistern (cisterna magna) & Spinal subarachnoid space

Obstructive Hydrocephalus(non-communicating)

• Obstruction of the passage of the ventricular system due to:– Congenital malformation: aqueduct stenosis,

Dandy-Walker syndrome, Arnold-Chiarri malformations

– Mass/tumor lesion– Congenital inflammation (TORCH)– Perinatal ventricular hemorrhages

Obstructive Hydrocephalus(non-communicating)Localized by the pattern of the ventricular enlargement

aqueduct stenosis

Communicating Hydrocephalus

• CSF production exceeds the absorption

• 30% of the hydrocephalus cases

• Less severe ventricular enlargement, slight involvement of 4th ventricle, widening of the basal cistern

Treated Hydrocephalus• VP Shunt• Effective drainage, ventricular volume

decreased, restoring its own structure• Permanent parenchymal damage: form of

cerebral atrophy with widened cistern & sulci

REFERENCES1. Grumme T, Kluge W, Kretzschmar K, Roesler A. Cerebral and

Spinal Computed Tomography 3rd Edition. 1998. Blackwell: Berlin.2. Francis A Burgener, Diffrential Diagnosis in Magnetic Resonance

Imaging, 2002. Georg Thieme Verlag , Stuttgard – Germany.