disorders of neural tube closure
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Disorders of Neural Tube Closure. Dr Malith Kumarasinghe (MBBS). Review of Neuroembryology. Dorsal induction Primary neurolation: 3-4 wks gestation Brain and upper spine Secondary neurolation: 4-5 wks gestation Distal spine. Disorders of neural tube closure. Chiari I-IV - PowerPoint PPT PresentationTRANSCRIPT
Disorders of Neural Tube Closure
Dr Malith Kumarasinghe (MBBS)
Review of Neuroembryology• Dorsal induction• Primary neurolation: 3-4 wks
gestation Brain and upper spine• Secondary neurolation: 4-5 wks
gestation Distal spine
Disorders of neural tube closure• Chiari I-IV• Encephaloceles• Anencephaly• Corpus Callosum Agenesis• Spinal Dysraphism (Spina bifida)• - Menigoceles• - Myelomeningoceles• Tethered chord
Enephaloceles• Anatomy• Failure of the anterior neural tube to
close due to genetic, infection, or toxic reasons.
• 1/1000• Distorted parts of the (covered) brain
protruding extracalvarially
EncephaloceleAnatomyOccipital 90%Parietal 10%TranssphenoidalFrontoethmoidal Nasal
Encephaloceles• Parietal
encephalocele
• Frontoethmoidal encephalocele
Encephaloceles• ClinicalDepends on involvement
• TreatmentSurgical excision of sac with water-
tight dural closure
Anencephaly• 1/1000 • Anencephaly is a defect in the
closure of the neural tube during fetal development.
• Large defect of the calvarium, meninges, and scalp.
• Incompatible with life.
Anencephaly
Corpus callosum• Location?• Functions?
Lateralization of Function• Lateralization of function refers to
the idea that each hemisphere of the brain is specialized for different functions.
• Each hemispheres controls the contralateral (opposite) side of the body.– Example: skin receptors and muscles
mainly on the right side of the body.– Each hemisphere sees the opposite
side of the world.
Lateralization of Function• The left and right hemisphere
exchange information primarily through a set of axons called the corpus callosum.
• Other areas that exchange information include:– The anterior commissure.– The hippocampal commissure.– A few other small commissures.
• Information crosses to the other hemisphere with only a brief delay.
Fig. 14-2, p. 418
Corpus Callosum Agenesis• Expansion of third ventricle• May present with HCP, seizures• May be incidental finding without any
clinical significance
Spinal Dysraphism (spina bifida)• Spina bifida occulta: 20-30% in North
Americans, often incidental, cutaneous manifestations
• Spina bifida aperta:• Meningocele • Myelomeningocele
Spinal Dysraphism• Spina bifida occulta
Spinal Dysraphism• Meningocele
Spinal Dysraphism• Myelomeningocele
Meningocele• 1-2/1000• 1/3 have neurological deficits• Surgical repair with water-tight dural
closure
Meningomyelocele• 1-2/1000 live birth• Failure of complete
closure of caudal neural tube
• 85% occur in lumbar region
Meningomyelocele
Meningomyelocele
Myelomeningocele• Clinical• Mild to complete paralysis• Ruptured vs unruptured• Urinary incontinence• Skeletal abnormalities
Myelomeningocele• Treatment• If open, Gent and Naf IV• Prone, bottom up• Telfa with wet gauze over lesion• Surgical closure within 36hrs• Shunt if overt HCP• Urologic and Orthopaedic
consultation
Lipomyelomeningocele• Present with back mass, bladder
problems, paralysis• Cutaneous stigmata• Treatment is surgical decompression