1. FOCAL CORTICAL DYSPLASIA
Dr Ashraf Abdou
Professor of neurology
Neuropsychiatry department
Alexandria university

2. Normal Cortical Development
1) Proliferation
 proliferation of neurons in the ventricular zone and glia in the
subventricular zone
2) Migration
 Migration of postmitotic neurons to the cortical plate
 Heading for the deepest layers and then for the superfricial layer
 Between the 8th and 24th weeks of gestation
3) Cortical organization :
 vertical and horizontal organization of neurons within the cortex and
elaboration of axonal and dendritic branch
 terminal differentiations, apoptosis, synapse elimination, cortical
remodeling

3. Proliferation and Migration
 Germinal matrix adjacent to the lumen of neural tube
(future ventricles) contains stem cells of the neurons and
two types of glial cells.
 Neuronal precursor cells migrate along specialized cells
called radial glial cells, to one of the six layers of cerebral
cortex.
 Once at adult site – establish synaptic connections with
neighbouring neurons & send axons to targets
 Generally migrate centrifugally towards brain surface

4. Timing of Neuroblast migration
 Cerebrum – neuroblasts – begin by 6 weeks – last till
34th weeks
 Cerebrum – glioblast – migrate till early post natal
period
 Brainstem – migration of neuroblast complete by 2
months
 Cerebellum – continue till 1 year

5. Formation of sulci & gyri
 Migrating neuroblasts necessitate more surface area
without increasing volume
 Proliferation of Glia
 Growth of dendrites & axons

6. Neuronal Migration Disorders
I. True migration disorders
Neurons fail to reach their intended destination.
1. Lissencephaly (agyria, pachygyria and sub-cortical
band heterotopia).
2. Cobble stone complex malformation.
3. Heterotopias.
II. Malformations of cortical organization.
Microscopic abnormality in cortical arrangement.
1. Polymicrogyria.
2. Schizencephaly.
3. Focal cortical dysplasia.

7. Lissencephaly with sub cortical band heterotopia.
Clinical features
 Normal at birth.
 Seizures uncommon on 1st day of
life.
 Seizures at 3-6 months, later
infantile spasm and Lennox-
gastaut syndrome.
 Profound MR .
 Early hypotonia, later spastic
quadriplegia and opisthotonus.

8. Subcortical band heterotopia-Double cortex
Sub-cortical, symmetric, circumferential bands of gray
matter, separated from cortex by thin band of white matter. “Double
cortex” appearance.

9. Heterotopias
 Group of neurons is an inappropriate location –
either below or above the cerebral cortex.

10. Periventricular nodular heterotopia

11. Sub-ependymal nodular heterotopia

12. Periventricular laminar heterotopia

14. Focal Cortical dysplasia
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15. Focal Cortical dysplasia with normal cell types
Pure architectural Dysplasia
* Abnormal cortical lamination.
* Ectopic neurons in white matter.
Present with – Epilepsy / learning disability.
MRI: Lobar / gyral hypoplasia, atrophy of underlying white
matter blurring of gray- white border. Increased T2 &
decreased T1 signal intensity.

16. Focal cortical dysplasia with abnormal cell
types (balloon cells)
 Cytoarchitectural dysplasia
 It is clear only with histopathology, not with MRI

17. Incidence
 Autopsy studies 1.7% incidence of FCD in
normal brains.1
 The incidence was significantly higher
(46.5%) in patients with epilepsy
 In surgical treated epilepsy:
 In pediatric patients the incidence was
25%
 In an adult population: 15%

18. Cortical dysplasia and epilepsy
 77 to 90% of patients with
cortical malformations had seizures.
 Cortical dysplasia is the most common
substrate in pediatric and the second or third
most frequent etiology in adult epilepsy
surgery patients

19. Cortical dysplasia and epilepsy
 Epilepsy typically manifests during the first
decade of life, usually after 2 or 3 years of age
 Seizure semiology depends on the anatomic
location of the malformation.
 Partial
 Partial with 2ry generalization
 Many patients have more than one seizure type

20. Focal cortical dysplasia
MRI :
Focal abnormal
gyral(cotical)
thickening
Blurring of the
cortical-white
matter junction

21. Cortical dysplasia; other clinical presentations
 Dysplasia involving extratemporal regions
demonstrates earlier age at presentation,
more severe epilepsy, higher incidence of
mental retardation and developmental delay.

22. Imaging studies
 Milder forms of dysplasia may remain
invisible to current imaging techniques. Other
studies report MRI detection
of cortical abnormalities in 60 to 90% of the
patients with FCD.
 Characteristic MRI findings include:
 abnormal gyral patterns
 shallow sulci
 increased cortical thickness
 poor gray-white matter differentiation
 increased subcortical signal intensity on T2-weighted
imaging

23. Focal cortical dysplasia
(A1) T1WI : cortical thickening
(A2) Proton-density-WI : blurring of interface between GM and
WM
(A3) T2WI : increased signal change
(A4) FLAIR image : increased signal change

24. Focal Cortical dysplasia

27. There is :
•cortico-subcortical blurring of the left paramedian frontal cortex
•streak of high T2 signal extending from the depth of the sulcus to the
ventricular wall.
• T1 hyperintensity of the cortex
Coronal T2WI Axial T2WI Axial T1 MPRAGE
Coronal T1
MPRAGE recon

28. 5-year-old boy with refractory epilepsy. Coronal T2WI
imaging done on 1.5 T MR scanner was read as normal.
Imaging done at 3T with 32 channel head coil demonstrates subtle blurring of the gray-white junction
in the left frontal lobe with mild T2 prolongation in the underlying white matter. Increased T1
hyperintensity of the left frontal cortex is also noted. Findings consistent with FCD.
Axial T2WI
Coronal T1
MPRAGE recon Coronal FLAIR Axial FLAIR

29. 13 month old male with medically
refractory focal seizures. Coronal & axial
T2WI MRI done at 1.5 T MR scanner was
read as normal.
Same patient as above scanned on a 3T MR scanner. Imaging demonstrates cortical
thickening and blurring of gray-white junction in the left temporal lobe. Findings
consistent with cortical dysplasia.
Coronal T2WI Coronal T2WI Axial T2WI Coronal T1
MPRAGE recon

30. Surgical outcome
 Approximately 33–75% of individuals
becoming seizure-free. [80% of patients became
seizure-free after surgical treatment for mTLE related to
HS or lesional epilepsy, such as primary brain tumor or
vascular malformations]6,20.
 Most important factor:
 complete removal of dysplastic cortex
[70% compared with 22% of those with
incomplete resections - 82% compared with
47% with incomplete resections]