Pediatric Neuro

Pediatric Brain has different myelination pattern

• Only myelinated structures at birth

  • Brainstem

  • Posterior limb of internal capsule

• T1 should have normal adult pattern at age 1

• T2 should have normal adult pattern at age 2

• Opercularization = closure of the sylvian fissure

  • Has nothing to do with myelination just listed here

  • Sylvian fissure will be wide angled open at infancy and more narrow as you get older

Chiari 2

• Myelomeningocele is present at birth and creates a suction on the CSF that then pulls the cerebellar tonsils down ward (how i think about it)

• Therefore once the myelomeningocele is repaired surgically the patient will typically develop hydrocephalus because the vaccuum is gone and the body had gotten used to it and compensated accordingly

• Concurrent findings

  • Dysgenesis of corpus callosum

  • Tectal beaking

  • Elongation of 4th ventricle

  • Stenogyria

  • Large mass intermedia

Germinal Matrix Hemorrhage

• The choroid plexus should not extend past the caudothalamic groove

  • If you see bright stuff near there then suspect it is blood

• Only seen until 32-34W gestation

  • You cannot have germinal matrix hemorrhage in a full term infant

• There is normally some increased echogenicity in the periventricular white matter

  • So how do we know what is blood vs normal brain

  • If prominently asymmetric = likely blood

  • If area of increased echogenicity is as echogenic or more echogenic as the choroid plexus = likely blood

    • Normal peri-ventricular brain should be echogenic but not more than the choroid plexus

  • Can you identify borders of the echogenic area

    • If yes = likely blood

    • Normal brain will be more vague

• Relevance of Grading

  • If grade 1 = can continue anti-coagulation (kids classically on AC for ECMO)

  • If grade 2 or higher = typically need to stop AC and therefore stop ECMO

• Grading

  • Grade 1: Sub-ependymal hemorrhage

    • Can progress to grade 2

    • Can resolve or sometimes form a subependymal cyst

Dandy-Walker Malformation

• Hypoplastic cerebellar vermis

• Cystic dilation of the 4th ventricle

• Torcular-lambdoid inversion - basically torcula gets pushed superiorly by the cystic shit and makes it higher than normal

  • Torcula = confluence of sinuses

  • Lambdoid = lambdoid suture

• Associated with almost everything to some degree

• Technically exists on a spectrum for cases that are basically DW but don’t meet all the criteria - termed Dandy walker variant

Meckel-Greuber Syndrome

• Holoprosencephaly

• Renal cysts

• Polydactyly

Blake’s Pouch Cyst

• Failure of Blake’s pouch to regress because the foramen of Magendie does not open in development

• Therefore no communication between 4th ventricle and cisterna magna

  • Remember magendie = allows 4th ventricle to drain into cisterna magna

  • Remember lushka = allows 4th ventricle to drain into cerebellopontine cistern

• Hydrocephalus present (Arachnoid cyst will not have hydrocephalus)

• Normal torcula (confluence of sinuses)

• No cerebellar vermis malformations (DW will have these)

Hydrancephaly

• Destruction of cerebral hemispheres and replaced with fluid

  • Basically bilateral large MCA infarcts

• Absence (may have some small residual tissue) of the cerebral hemispheres

• The thalami and posterior fossa are typically preserved

• Falx typically present -it is an infarct not midline cleavage issue!

• DDx - severe hydrocephalus, L1CAM disease, oters

The “Cephalys”

Lissencephaly

• Incomplete separation of the two cerebral hemispheres

Lobar

• Least severe

• Thalami not fused

• Absent septum pellucidum

• Fusion of frontal horn of lateral ventricles

• Inter-hemispheric fissure present

• Normal/hypoplastic corpus callosum

Hemi-megalencephly

• Basically asymmetric enlargement of one cerebral hemisphere

  • Big brain parenchyma + big ventricle

  • If this was small side + big ventricle = atrophy (rasmussen encephalitis)

• Can have focal or diffuse neuronal migration defects

  • Polymicrogyra

  • Pachygyra

  • Heterotopia

Lissencephaly-Pachygyra Spectrum

Porencephaly/Porencephalic Cyst

• Considered less severe form of hydrancephaly

Agenesis of the Corpus Callosum

• Corpus callosum formation

  • Forms from front to back

  • Rostrum is last thing to form

• Partial agenesis (some corpus callosum is present) or complete agenesis

• Corpus callosum does not develop

  • Cingulate gyrus typically will not form either and therefore the more peripheral brain gyri will extend from ventricles to skull

• Bundles of Probst

  • White matter bundles that normally would make up the corpus callosum but not just go linearly along the lateral ventricles

• Classic findings

  • Racecar sign appearance of ventricles (does not look like racecar)

  • Longhorn cattle appearance of ventricles (actually kind of looks like this)

• Aicardi Syndrome

  • Agenesis of corpus callosum + retinal abnormalities

  • Only in patients with 2 X chromosomes

• Associated with pericallosal lipoma

• Many other associations and things that can be seen concurrently

• Sharpiro syndrome - hyperhidrosis + hyperthermia + agenesis of CC

Rhomboencephalosynapsis

• Vermis does not form so you get a single lobed cerebellum

Focal cortical dysplasia

General

• Premature closure of skull sutures

• Be sure the abnormal skull shape is not due to positional changes from always laying on the back to prevent SIDS

• Normal suture closing times

  • Metopic: 3-9 months

  • Anterior fontanelle: 18-24 months

  • Sagittal: approximately 22 years

  • Coronal: approximately 24 years

  • Lambdoid: approximately 26 years

  • Squamosal: approximately 60 years

Plagiocephaly

• Asymmetric flattening of one side of the head

• Positional

  • Laying on back too much to avoid SIDS

  • Nothing to do with suture closing just have the head which is a soft mush in the same position alot so it conforms to that shape

  • Ear on affected side will be more anterior

  • Parallelogram shaped head

• Related to premature closure of

  • Lambdoid suture

  • Coronal suture

    • Harlequin eye sign

      • Looks like one orbital rim is pulled up and outward

Per-ventricular leukomalacia

• More common in pre-mature babies

• Believed to be result of hypoxic-ischemic injury in watershed areas, although could be related to vasculitis or infection

• Look for history of prior bleed

• Grading

  • US & MRI grading systems - Grading system radiopaedia

• On US may look like many cystic areas alot of the time

Craniosynostosis

Ectopic posterior pituitary

• Look for bright spot and see that it is not where it should be in posterior sella

• Associated with pituitary dwarfism

References:

• Case courtesy of Hidayatullah Hamidi, Radiopaedia.org, rID: 83386

• Case courtesy of Naqibullah Foladi, Radiopaedia.org, rID: 83821