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Radiology
Cortical Development and Disorders
Built from Obstetric Imaging
What’s inside
10 sections · 126 slides
Overview
- What you will learn here
Building the fetal cortex
Seven weeks of stem cells to a six-layered cortex
- The cortex is built, not delivered ready-made
- How the cortex is built
- Two kinds of cell come out of the nursery
- A second stream of neurons arrives sideways
- The busy window and the finishing line
- 7 wk
- The cortex is not building alone
- One set of genes, many body parts
- Timing matters more than the cause
- From insult to outcome
Malformations of cortical development
One family name, three ways to fail
- What the umbrella term means
- Three ways the build can fail
- Classification of cortical malformations as printed
- Classification of Malformations of Cortical Development
- Uncommon
- Why the cortex goes wrong
- Causes that come from outside the fetus
- Where the causes sit
- How affected children present
Knowing normal before calling abnormal
Sulci, fissures and the weeks they appear
- The normal fetal brain keeps changing shape
- Ultrasound does the first-line work
- Ultrasound planes that show the early sulci and fissures
- Colour map of the medial sulci
- The order in which grooves appear
- Weeks at which each fissure becomes visible
- Gestational Ages When Cerebral Sulci Become Visible on Ultrasound (US) and Magnetic Resonance Imaging (MRI)
- How to use that table at the scanner
- MRI is the second look
- Normal sulci on fetal MRI at 28 weeks
- What operculization means on that picture
- What MRI adds, and where it stops
- Ultrasound and MRI compared
Microcephaly
A head too small, and what that does or does not mean
- What a small head is defined as
- A description, not a diagnosis
- 1:10,000
- When the small head shows itself
- Causes of a small head, inherited and acquired
- Etiologies of Microcephaly
- Two families of cause
- What was found when small heads were followed up
- 48%
- What ultrasound shows in microcephaly
- Rules of thumb on the measurements
- Small head and sloping forehead at 20 weeks
- Why the small head is the hardest to scan
- What MRI adds when the head is small
- The picture at a glance
- Points to carry away
- The honest limit of prenatal diagnosis
Macrocephaly and hemimegalencephaly
A head too big, and half a brain too big
- Three words that are not the same thing
- Defining a big head
- ~2%
- Most big heads are perfectly fine
- Conditions that come with a big head
- Conditions Associated With Macrocephaly
- The commonest cause runs in families
- “
- Wide fluid space of familial macrocephaly
- The cortical vein sign
- When a big head does and does not appear
- Syndromes that come with one overgrown hemisphere
- Syndromes Associated With Hemimegalencephaly
- When one half of the brain overgrows
- How hemimegalencephaly presents
- One enlarged hemisphere at 26 weeks
- What to look for on the scan
- What MRI adds in a big head
- Two pictures side by side
- Points to carry away
When neurons never arrive
Lissencephaly, agyria, pachygyria and heterotopia
- Cells made, but never delivered
- The words for a smooth brain
- Two major groups
- 1-4 per 100,000
- The genes behind lissencephaly
- Why both parents should be examined
- The environment can copy the genetics
- Heterotopia behaves differently
- What comes with Miller-Dieker syndrome
- Why the same gene hits boys harder
- Why ultrasound struggles early
- Smooth brain of Miller-Dieker syndrome at 26 weeks
- What to notice on that pair of images
- What MRI adds when neurons are lost on the way
- Walker-Warburg syndrome at 19 weeks
- The kinked brainstem sign
- The picture at a glance
- What else can look like this
- Points to carry away
Arrived, but badly arranged
Polymicrogyria, schizencephaly and overmigration
- The last stage that can fail
- Polymicrogyria: too many tiny folds
- Schizencephaly: a split brain
- The finding that names the disease
- Overmigration: neurons that go too far
- What causes polymicrogyria
- What causes schizencephaly
- How children present
- What HARD-E stands for
- Why ultrasound misses these
- What ultrasound can pick up instead
- ~80%
- Small abnormal folds after a sinus thrombosis at 30 weeks
- Brain surface in polymicrogyria
- Open cleft in the front of the brain
- Reading the edge of a cleft
- Neurons parked along the ventricle
- Nodules lining the ventricles at 21 weeks
- What overmigration looks like on imaging
- What MRI adds in organisation disorders
- What else can look like this
- Points to carry away
Counselling and management
What can be offered, before and after birth
- Before birth
- After birth
- What the referring physician needs to know
- What to arrange
Pulling it together
Three stages, three families of disease
- The three stages and what fails at each
- Rules that hold across the whole group
- Two habits worth keeping
- References
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- Suggested reading
- Obstetric Imaging: Fetal Diagnosis and Care, 2nd Edition