1. Congenital anomalies of the central nervous system can result from genetic malformations during organ formation, environmental deformities during development, or tissue disruption. 2. Normal central nervous system development occurs through 23 stages from week 4 to week 8 of gestation, during which the brain and spinal cord regions form and neural cell types develop. 3. Common types of central nervous system anomalies include arachnoid cysts, neuroenteric cysts, craniosynostosis, encephaloceles, Chiari malformations, Dandy-Walker malformations, aqueductal stenosis, neural tube defects, tethered cord syndrome, split cord syndrome, intracranial lipomas, and

1. Congenital anomalies of
the CNS
DR.MAZIN M.K. BOUJAN
2011

2. INTRODUCTION
• Phenotype: the outer look.
• Genotype: the inner genetics.
1.Malformation=genetic=organ formation.
2.Deformity= environmental
-Internal (more sever, no spontaneous recovery) e.g.:
Meningomyelocele=spastic muscles=club feet.
-External (might correct itself after the resolution of the
force) e.g.: oligohydraminios(uterus force) leads to
premature descent of the head and eventually coronal
synostosis ).
3. disruption: tissue or organ destruction.
4. a sequence: one primary defect leads to many
secondary anomalies.

3. Neuroembryology
• Stages of embryonic development;
• Human embryo has 23 stages of
development (each of 2-3 days
long).
• Stage 8 to 23 is related to CNS
development.

4. Normal CNS development
• The three basic regions of the CNS
(forebrain, midbrain, and hindbrain)
develop at the rostral end of the tube,
with the spinal cord more caudally.
• Within the developing spinal cord
specification of the different populations of
neural precursors (neural crest, sensory
neurones, interneurones, glial cells, and
motor neurones).
• *J Neurol Neurosurg Psychiatry 2003;74:i3-i8 doi:10.1136/jnnp.74.suppl_1.i3

5. Stages of CNS development
Stage Main feature
8 Beginning of organogenesis.
9 3 pairs of somites.
10 Most important stage of brain development
11 Upper neuropore closure.
12 Lower neuropore closure.
13 Entire neural tube closure.
14 Cerebral hemispheres development.
15 Thalamus and hypothalamus.
16 Olfactory system.
17 Cranial nerves.
18-20 Frontal, temporal, and occipital lobes.
21-23 cerebellum

6. Types of CNS anomalies
1. Arachnoid cyst.
2. Neuroenteric cysts.
3. Craniosynostosis.
4. Encephalocele.
5. Chiari malformation.
6. Dandy-Walker malformation.
7. Aqueductal stenosis.
8. Neural tube defects.
9. Tethered cord syndrome.
10. Split cord syndrome.
11. Intracranial lipoma.
12. Hypothalamic hamartoma.

7. 1.Arachnoid cyst
1.Intracranial:
• Usually asymptomatic discovered
incidentally.
• Could be symptomatic.
Symptoms: Increased ICP, seizure, or
hemiparesis.
Treatment: from shunting to excision.
2.intraspinal:almost always dorsal.

8. 2.Neuroenteric cysts
Is a CNS cyst lined by endothelium
resembling GIT or respiratory.
Intraspinal: is the main location,
usually anterior.
Intracranial: few reported cases.
Symptom: pain or myelopathy,
meningitis(fistula type).
Treatment: complete removal.

9. 3.Craniosynostosis.
• Congenital early closure of the sutures.
• Might occur postnataly by abnormal
positioning (lazy lambdoid).
• Has many types according to the suture
involved. Most common are:
• Sagittal=scaphocephaly.
• Unilateral Coronal= plegiocephaly.
• Bilateral coronal = brachycephaly.
• Treatment: surgery is usually cosmetic.

10. 4.Encephalocele
• Is cranium bifidum usually a cyst in the
occipital region.
• If only contains meningies=meningocele.
• If contain meningies and cerebral tissue =
encephalocele.
• Another group is called basal encephalocele
appear at the base of the skull and could be
mistaken for a nasal polyp.
• Treatment: surgical excision and water-tight
Dural suture.

11. 5.Chiari malformation
Basically 4 types:
• Chiari I: caudal descent of the
cerebellar tonsils to the cervical canal.
• Chiari II: caudal descent of the vermis,
medulla and the 4th ventricle.
• Chiari III: rare, cerebellar herniation +
encephalocele.
• Chiari IV: cerebellar hypoplesia.
• Treatment: surgical decompression of
the posterior fossa.

12. 6.Dandy-Walker Malformation
• Atresia of foramen Magendie and
luschka.
• Agenesis of the vermis.
• 4th ventricle communicated with a
posterior fossa cyst.
• Treatment: shunt the posterior fossa
cyst.

13. 7.Aqueduct stenosis
• Triventricular hydrocephalus.
• Normal size 4th ventricle.
• Congenital: malformation.
• Acquired: infection, neoplasm,
arachnoids' cyst.
• Treatment: shunting.

14. 8.Spinal dysraphism
• Spina bifida: types;
1. Spina bifida occulta: an incidental
finding of loss of spinous process and
lamina.
2. Meningocele: 1+ cystic distention of
the meningies.
3. Myelomeningocele: 1+2+ spinal cord
or cauda equina involvement.
Treatment : for 2 and 3 repair.

15. 9.Tethered cord syndrom
• Thick filum terminale with an
abnormal low level conus medularis.
Presentation: Gait difficulty, visible
muscle atrophy, sensory deficit,
bladder dysfunction, scoliosis and
kyphosis.
Treatment: division of the filum.

16. 10.Split cord syndrom
• Type one: 2 cords with 2 covering
dura.
• Type two(diplomyelia):2 cords within
the same dura.
• treatment: untethering the cord

17. 11.Intracranial lipoma
• Usually in the midline above the corpus
callosum.
• Asymptomatic discovered incidentally.
• might cause seizure or hydrocephalus.
Treatment :
• shunting the associated hydrocephalus.
• Direct surgery is rarely necessary.

18. 12.Hypothalamic hamartoma
• Masses of ectopic neural tissues.
Presentation:
• seizure, behavioral disturbance,
precocious puberty, mental
retardation, and visual impairment.
• Surgical resection.

19. Good luck