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Disorders of Neural Tube Closure

Disorders of Neural Tube Closure. Jan M. Eckermann, MD, PGY-3 Department of Neurosurgery Loma Linda University Medical Center. Review of Neuroembryology. Dorsal induction Primary neurolation: 3-4 wks gestation Brain and upper spine

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Disorders of Neural Tube Closure

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  1. Disorders of Neural Tube Closure Jan M. Eckermann, MD, PGY-3 Department of Neurosurgery Loma Linda University Medical Center

  2. Review of Neuroembryology • Dorsal induction • Primary neurolation: 3-4 wks gestation Brain and upper spine • Secondary neurolation: 4-5 wks gestation Distal spine

  3. Neural groove

  4. Neural tube

  5. Whereyouat??

  6. Disorders of neural tube closure • Chiari I-IV • Encephaloceles • Anencephaly • Corpus Callosum Agenesis • Spinal Dysraphism (Spina bifida) • - Menigoceles • - Myelomeningoceles • Tethered chord

  7. Chiari I ANATOMY • Peglike cerebellar tonsils displaced into upper cervical canal ( >10mm) • HCP 25% • Syringomyelia 60% • Skeletal anomalies 25%

  8. Chiari I: displaced tonsils

  9. Chiari I: syringomyelia

  10. Chiari I: syringomyelia

  11. Chiari I Clinical • Asympotmatic (30%) • Headache • Weakness • Cerebellar signs • Herniation >12mm invariably symptomatic

  12. Chiari I Treatment • Observation if asymptomatic • Surgery if symptomatic: p-fossa decompression +- cervical laminectomy

  13. Whereyouat??

  14. Chiari II Anatomy • Calvarial defects “Lueckenschaedel” • Small p-fossa • Fenestrated falx • HCP in 90% • Myelomeningocele in 100% • Syringohydromyelia in 50%-90%

  15. Chiari II: Brain MRI

  16. Chiari II: lueckenschaedel, falx

  17. Chiari II Clinical • Dysphagia • Apneic spells • Stridor • Aspiration • Arm weakness

  18. Chiari II Treatment • Shunt • P-fossa decompression • Repair of MM

  19. Chiari III and IV Chiari III Most severe form. Chiari II + low occiptial or high cervical encephalocele. Usually incompatible with life Chiar IV Severe cerebellar hypoplasia or absence. No herniation Extremely rare

  20. Whereyouat??

  21. 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

  22. Encephalocele Anatomy Occipital 90% Parietal 10% Transsphenoidal Frontoethmoidal Nasal

  23. Encephaloceles • Parietal encephalocele • Frontoethmoidal encephalocele

  24. Encephaloceles • Clinical Depends on involvement • Treatment Surgical excision of sac with water-tight dural closure

  25. 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.

  26. Anencephaly

  27. Corpus Callosum Agenesis • Expansion of third ventricle • May present with HCP, seizures • May be incidental finding without any clinical significance

  28. Whereyouat??

  29. Spinal Dysraphism (spina bifida) • Spina bifida occulta: 20-30% in North Americans, often incidental, cutaneous manifestations • Spina bifida aperta: • Meningocele • Myelomeningocele

  30. Spinal Dysraphism • Spina bifida occulta

  31. Spinal Dysraphism • Meningocele

  32. Spinal Dysraphism • Myelomeningocele

  33. Meningocele • 1-2/1000 • 1/3 have neurological deficits • Surgical repair with water-tight dural closure

  34. Meningomyelocele • 1-2/1000 live birth • Failure of complete closure of caudal neural tube • 85% occur in lumbar region

  35. Meningomyelocele

  36. Meningomyelocele

  37. Myelomeningocele • Clinical • Mild to complete LE paralysis • Ruptured vs unruptured • Urinary incontinence • Skeletal abnormalities

  38. 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

  39. Lipomyelomeningocele • Present with back mass, bladder problems, paralysis • Cutaneous stigmata • Symptoms are due to tethered cord and cord compression from fatty mass • Treatment is surgical decompression

  40. Whereyouat??

  41. Tethered Cord Syndrome • Anatomy • Low conus medullaris • Short, thick filum terminale • Intradural lipoma

  42. Tethered Cord Syndrome

  43. Tethered Cord Syndrome • Clinical • Cutaneous findings • Gait difficulties • Visible muscle atrophy • LE sensory deficits • Bladder dysfunction • Scoliosis

  44. Tethered Cord Syndrome • Treatment • Laminectomy with division of filum terminale • Removal of lipoma if present • Followed with MRI

  45. Thank you

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