Pediatric Neuroradiology

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Pediatric Neuro: Dev & Congenital - Brain Blueprints

  • Neurulation (3-4 wks): Neural tube forms. Defects:
    • Anencephaly: Absent cerebrum/vault, "frog-eye" sign.
    • Encephalocele: Cranial content herniation, occipital common.
    • Spina Bifida: Often with Chiari II malformation.
  • Prosencephalic Development (5 wks): Forebrain cleavage. Defect:
    • Holoprosencephaly (HPE): Alobar, semilobar, lobar. Facial anomalies common. ⭐ > Holoprosencephaly is strongly associated with maternal diabetes and Patau syndrome (Trisomy 13).
  • Neuronal Migration (8-20 wks): Neurons travel to cortex. Defects:
    • Lissencephaly: Smooth brain (agyria-pachygyria), "figure-8" MRI.
    • Heterotopia: Ectopic gray matter.
  • Organization (20 wks - postnatal): Cortical folding & layering. Defects:
    • Polymicrogyria: Many small, disorganized gyri.
    • Schizencephaly: Gray matter-lined CSF clefts.
  • Myelination (Birth - ~2 yrs): Pattern: Caudal→cranial, posterior→anterior, central→peripheral.
    • MRI: T1W ↑ (hyperintense), T2W ↓ (hypointense) with maturation.
    • Posterior Limb Internal Capsule (PLIC) myelinated by 7 months. Largely complete by 2 years. Pediatric brain myelination progression T1 and T2 MRI

Pediatric Neuro: HIE & Infections - Brain Battles

  • Hypoxic-Ischemic Encephalopathy (HIE): Brain injury from O₂ deprivation.
    • Term Infants:
      • Pattern: Deep gray matter (basal ganglia, thalami), brainstem, perirolandic cortex, watershed zones.
      • MRI: Early DWI changes (within 24-48 hrs), later T1 hyperintensity. MRS: ↑Lactate, ↓NAA.
    • Preterm Infants:
      • Pattern: Periventricular Leukomalacia (PVL) - white matter injury, esp. near trigones.
      • MRI: Cystic changes, gliosis.
  • Infections:
    • TORCH (Transplacental):
      • CMV: Most common. Periventricular calcifications, ventriculomegaly, polymicrogyria, white matter abnormalities.
      • Toxoplasmosis: Diffuse/basal ganglia calcifications, hydrocephalus, chorioretinitis (classic triad with convulsions).
      • HSV: Hemorrhagic necrosis (temporal/frontal lobes), diffusion restriction early.
    • Bacterial Meningitis:
      • Complications: Hydrocephalus (communicating/obstructive), infarcts (vasculitis), empyema, ventriculitis, abscess.
      • MRI: Leptomeningeal enhancement, DWI for pus/infarcts.

HIE watershed zone injury in infant brain

⭐ CMV is the most common congenital infection causing brain abnormalities, classically presenting with periventricular calcifications and migrational defects like polymicrogyria.

Pediatric Neuro: Tumors - Tiny Tumors, Big Trouble

  • General: Infratentorial common (childhood); supratentorial (infancy/adolescence).
  • Medulloblastoma (PNET):
    • Malignant. Cerebellar vermis. 📌 Malignant, Midline, Metastasis (CSF).
    • Imaging: Hyperdense CT, restricted diffusion MRI, avid enhancement.
  • Pilocytic Astrocytoma (WHO I):
    • Most common benign. Cerebellum, optic pathway.
    • Cystic with enhancing mural nodule ("cyst with a dot"). Rosenthal fibers.
  • Ependymoma:
    • 4th ventricle common. "Plastic tumor" - extends via foramina. Calcification (~50%).
  • Craniopharyngioma:
    • Suprasellar. Adamantinomatous (children): cystic, lobulated, calcification (90%), "machine oil".
  • Germ Cell Tumors:
    • Pineal (boys) or suprasellar. Germinoma (radiosensitive); Non-germinomatous (↑AFP/β-hCG).

⭐ Infratentorial tumors are more common than supratentorial tumors in children (approx. 2:1 ratio), reversing in adulthood. ``

Pediatric Neuro: Syndromes & Trauma - Skin & Skull Signs

  • Neurocutaneous Syndromes (Phakomatoses):
    • NF-1: Café-au-lait spots, axillary freckling, Lisch nodules. Skull: Sphenoid wing dysplasia, lambdoid suture defects.
    • TSC: Ash-leaf spots (hypopigmented), facial angiofibromas, shagreen patch. Skull: Cortical/subependymal tubers (calcify), sclerotic lesions.
    • Sturge-Weber Syndrome (SWS): Port-wine stain (facial nevus flammeus, V1 distribution). Skull: Gyriform cortical calcifications ("tram-track").

      ⭐ Sturge-Weber Syndrome: Unilateral facial port-wine stain (V1/V2), ipsilateral leptomeningeal angiomatosis, glaucoma. "Tram-track" gyriform calcifications on CT are pathognomonic.

    • Encephalocraniocutaneous Lipomatosis (ECCL): Scalp lipomas, alopecia. Skull: Cranial asymmetry, intracranial lipomas.
  • Pediatric Head Trauma - Skull Signs:
    • Fractures: Linear, depressed, diastatic (suture separation > 2-3 mm), growing skull fracture (leptomeningeal cyst).
    • Cephalohematoma: Subperiosteal, does not cross suture lines; may calcify.
    • Caput Succedaneum: Subcutaneous edema, crosses suture lines; resolves quickly.
  • Other Skull Findings:
    • Craniosynostosis: Premature suture fusion (e.g., Apert, Crouzon syndromes).
    • Wormian bones: Intrasutural bones (e.g., osteogenesis imperfecta, cleidocranial dysostosis).

High‑Yield Points - ⚡ Biggest Takeaways

  • Medulloblastoma: Most common malignant pediatric brain tumor, typically posterior fossa.
  • Hypoxic-Ischemic Encephalopathy (HIE): Term infants - basal ganglia/thalamus; Preterm - periventricular white matter.
  • TORCH infections: CMV - periventricular calcifications; Toxoplasmosis - diffuse calcifications.
  • Chiari II malformation is almost always associated with myelomeningocele.
  • Neurofibromatosis Type 1 (NF1): Characterized by optic pathway gliomas and UBOs.
  • Tuberous Sclerosis Complex (TSC): Presents with cortical tubers, subependymal nodules, and SEGAs.
  • Dandy-Walker malformation: Key features are cystic dilation of 4th ventricle and vermian hypoplasia.

Practice Questions: Pediatric Neuroradiology

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A child presented to the casualty with seizures. On examination multiple oval hypo-pigmented macules were noted on the trunk, along with sub-normal IQ. Probable diagnosis of the child is:

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Flashcards: Pediatric Neuroradiology

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Banana sign is seen in _____ and in meningomyelocele

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Banana sign is seen in _____ and in meningomyelocele

Chiari II malformation

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