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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.