Your SlideShare is downloading. ×
0
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Disorders of neural tube closure and neuronal migration
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

Disorders of neural tube closure and neuronal migration

1,324

Published on

disorders of neural tube closure and migration

disorders of neural tube closure and migration

Published in: Health & Medicine, Technology
0 Comments
2 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total Views
1,324
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
16
Comments
0
Likes
2
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. Disorders of neural tube closure, diverticulation,cleavage and cellular migration
  • 2.  Over view of embryology  Disorders of neural tube closure  Disorders of diverticulation, cleavage and cellular migration
  • 3. CNS Embryology
  • 4. Flexures
  • 5. Spinal cord
  • 6. Medulla oblongata
  • 7. Pons
  • 8. Mid brain
  • 9. Ventricles
  • 10. Cortex
  • 11. Diencephalon
  • 12. Basal ganglia
  • 13. Commisures
  • 14. Neural tube closure disorders  Disorders of closure of rostral neural pore  Disorders of closureof caudal neural pore
  • 15. Cranial defects  Meningocele, meningoencephalocele, and meningohydroencephalocele are all caused by an ossification defect in the bones of the skull. The most frequently affected bone is the squamous part of the occipital bone, which may be partially or totally lacking. If the opening of the occipital bone is small, only meninges bulge through it (meningocele), but if the defect is large, part of the brain and even part of the ventricle may penetrate through the opening into the meningeal sac
  • 16.  The latter two malformations are known as meningoencephalocele and meningohydroencephalocele
  • 17. Anencephaly  Exencephaly is characterized by failure of the cephalic part of the neural tube to close. As a result, the vault of the skull does not form, leaving the malformed brain exposed. Later this tissue degenerates, leaving a mass of necrotic tissue. This defect is called anencephaly, although the brainstem remains intact. Since the fetus lacks the mechanism for swallowing, the last 2 months of pregnancy are characterized by hydramnios. The abnormality can be recognized on a radiograph, since the vault of the skull is absent.
  • 18. Defects of caudal neuropore  Neural tube defects (NTDs), may involve the meninges, vertebrae, muscles, and skin.  Spina bifida is a general term for NTDs affecting the spinal region. It consists of a splitting of the vertebral arches and may or may not involve underlying neural tissue. Two different types of spina bifida occur:
  • 19. ◦ Spina bifida occulta is a defect in the vertebral arches that is covered by skin and usually does not involve underlying neural tissue. It occurs in the lumbosacral region (L4 to S1) and is usually marked by a patch of hair overlying the affected region. ◦ Spina bifida cystica is a severe NTD in which neural tissue and/or meninges protrude through a defect in the vertebral arches and skin to form a cyst like sac.
  • 20.  Occasionally the neural folds do not elevate but remain as a flattened mass of neural tissue (spina bifida with myeloschisis or rachischisis).
  • 21. Cerebral cleavage and neural migration defects  Child with delayed devolopment and seizures  Especially when child is dysmorphic  MRI is the investigaton of choice  After the imaging we have to see the MR in a orderly fashion ◦ Midline structures ◦ Cerebral cortex and cortico white matter junctions ◦ White matter ◦ Basal ganglia and ventricular system and posterior fossa structures
  • 22. Midline structures  Cerebral commisures are the most common anomolies  Hypothalamus and pituatary  Midline leptomeninges  Large csf spaces in posterior fossa
  • 23. Cerebral cortex  Is 2-3mm thick  Too thick polymicrogyria and pachygyria  Greywhite matter junction irregular polymicrogyria or cobble stone cortex  Abnormally thin perinatal or ishaemic injury
  • 24. White matter  Myelination appropriate or not  Diffuse layer of hypomyelination or amyelination associated heterotopia or polymicrogyria suggestive of CMV  Absent myelination may be localised to a gyrus or may extend towards the ependymal layer transmantle sign characteristic of FCD
  • 25. Posterior fossa  Brain stem and cerebellum  4 th V and vermis  Size of the pons with cerebellum
  • 26. Callosal dysgenesis  Partial or complete absence corpus callosum and hippocampal commisures  Atrium or occipital horn dilatation colpocephaly  Probst bundles  Vertical or posterior course ACAs  Most common presentation seizures devolopmental delay and cranial deformity and hypertelorism
  • 27. Dandy-Walker malformation  Classic Dandy Walker malformation  HVR  BPC  MCM
  • 28. Classic DWM  Cystic dilatation of 4thV  Torcular lambdoid inv  HVR
  • 29.  HVR ◦ Variable vermian hypoplasia  BPC ◦ Open 4th V communicates with cyst  MCM ◦ Enlarged pericerebellar cisterns communicate with sub arachnoidspace ◦ Vermis and 4 th V normal
  • 30. Rhombencephalosynapsis  Etiology ◦ Unknown: 2 major theories  Failure of vermian differentiation  Vermian agenesis allowing hemisphere continuity  Features ◦ Congenital continuity (lack of division) of cerebellar hemispheres ◦ Usually with fusion of dentate nuclei and superior cerebellar peduncles
  • 31. ◦ Small, single hemisphere cerebellum with continuous white matter (WM) tracts crossing midline ◦ Diamond or keyhole-shaped 4th ventricle ◦ Absent primary fissure  Clinical features ◦ Variable neurological signs ◦ Ataxia, gait abnormalities, seizures ◦ Developmental delay ◦ RES discovered in near-normal patients at autopsy
  • 32. Molar Tooth Malformations (Joubert)  Hindbrain anomaly characterized by dysmorphic vermis, lack of decussation of superior cerebellar peduncle, central pontine tracts, corticospinal tracts  "Molar tooth" appearance of midbrain on axial images  Etiology ◦ result from mutations of ciliary/centrosomal proteins that can affect cell migration, axonal pathway
  • 33.  Clinical features ◦ Most common signs/symptoms: Ataxia, developmental delay, oculomotor and respiratory abnormalities
  • 34. Holoprosencephaly  Features ◦ Failure to delineate normal prosencephalic midline with absent/incomplete hemispheric and basal cleavage ◦ Single ventricle ◦ Azygous ACA ◦ associated facial defects
  • 35.  Clinical features  Most common signs/symptoms ◦ Facial malformation (hypotelorism +++) ◦ Seizures and developmental delays ◦ Hypothalamic/pituitary malfunction (75%, mostly diabetes insipidus), poor body temperature regulation ◦ Dystonia and hypotonia: Severity correlates with degree of BG nonseparation
  • 36. Heterotopic Gray Matter  Arrested/disrupted migration of groups of neurons from periventricular germinal zone (GZ) to cortex  Ectopic nodule or ribbon, isointense with gray matter (GM) on every MR sequence  Periventricular, subcortical/transcerebr al, molecular layer  Band heterotopia
  • 37. Lissencephaly  Features ◦ Disorders of cortical formation caused by arrested neuronal migration, resulting in thick 4-layer cortex and smooth brain surface ◦ "Hourglass" or "figure eight" shape of cerebral hemispheres ◦ 3 layers  Outer cellular layer → may be relatively thin, smooth  Intervening cell-sparse layer  Deeper thick layer of arrested neurons mimicking band heterotopia
  • 38. Schizencephaly  Features ◦ Transmantle gray matter lining clefts ◦ Ca++ when associated with CMV  Pathology ◦ Can be result of acquired in utero insult affecting neuronal migration ◦ Infection (CMV), vascular insult, maternal trauma, toxin  Types ◦ Closed lip ◦ Open lip
  • 39. Hemimegalencephaly  Features ◦ Hamartomatous overgrowth of part/all of hemisphere ◦ Abnormal proliferation, migration, and differentiation of neurons ◦ Embryology  Insult to developing brain causes development of too many synapses, persistence of supernumerary axons, and potential for white matter overgrowth  Localized epidermal growth factor (EGF) in cortical neurons and glial cells may lead to excessive proliferation
  • 40. ◦ Large cerebral hemisphere, hemicranium ◦ Posterior falx and occipital pole "swing" to contralateral side ◦ Lateral ventricle is large with abnormally shaped frontal horn
  • 41. Polymicrogyria  Features ◦ Malformation due to abnormality in late neuronal migration and cortical organization ◦ Result is cortex containing multiple small sulci that often appear fused on gross pathology and imaging ◦ Neurons reach cortex but distribute abnormally forming multiple small undulating gyri

×