Embryology and developmental pathology of the spinal column

1. Spinal Embryology and
Developmental Pathology
Richard C Rooney, MD, FACS
rrooney@seattlespinegroup.com

2. Stages of Neural-Spinal Development- First Week
Moore, K. The Developing Human

3. Stages of Neural-Spinal Development-
Second Week
Moore, K. The Developing Human

4. Stages of Neural-Spinal Development-
Third Week
• Primitive Streak
Moore, K. The Developing Human

5. Stages of Neural-Spinal Development-
Third Week
• Primitive Streak
Moore, K. The Developing Human

6. Stages of Neural-Spinal Development- Third Week
• Notochord
Moore, K. The Developing Human

7. Stages of Neural-Spinal Development- Third Week
• Notochord

8. Stages of Neural-Spinal Development- Third Week
• Notochord

9. Stages of Neural-Spinal Development- Third Week
• Notochord

10. Stages of Neural-Spinal Development- Third Week
• Notochord

11. Stages of Neural-Spinal Development- Third Week
• Notochord

12. Stages of Neural-Spinal Development- Third Week
• Notochord
Moore, K. The Developing Human

13. Stages of Neural-Spinal Development- Third Week
• Mesoderm- Day 16

14. Stages of Neural-Spinal Development- Third Week
• Somites
Moore, K. The Developing Human

15. Stages of Neural-Spinal Development- Third Week
• Mesoderm

16. Stages of Neural-Spinal Development- Third Week
• Neural Plate
Moore, K. The Developing Human

17. Stages of Neural-Spinal Development-
Fourth Week
• Neural Plate
– Neuralization- closure of the neural groove to
form the neural tube
Moore, K. The Developing Human

18. Stages of Neural-Spinal Development-
Fourth Week
• Somites- 42 pairs
• Neural Plate and cranial-most 4 somites form
the brain
Moore, K. The Developing Human

19. Stages of Neural-Spinal Development-
Fourth Week
• Somites- divide into dense and sparse areas
Moore, K. The Developing Human

20. Stages of Neural-Spinal Development-
Fourth Week
• Centrum- dense portion of cephalad with
sparse portion of caudal somite
Moore, K. The Developing Human

21. Primodial Vertebral Segment
Bullough, Atlas of Spinal Diseases

22. Vertebral Development
Bullough, Atlas of Spinal Diseases

23. Vertebral Development
Bullough, Atlas of Spinal Diseases

24. Stages of Neural-Spinal Development- Fifth Week
• Neural Plate- Thinning of 4th ventricle for
Foramen of Magendie
• Notochord- Degeneration in Vertebral Body
area
Moore, K. The Developing Human

25. Stages of Neural-Spinal Development- Fifth Week
• Vertebrae- Mesenchymal model finished
Moore, K. The Developing Human

26. Stages of Neural-Spinal Development-
Sixth Week
• Vertebrae-
– Chondrification- 6th week
– Ossification Centers- 7th week
Moore, K. The Developing Human

27. Further Vertebral Development
• Neural Central Joint- fuses 3rd to 6th year
• Vertebral Arch- fuses 3rd to 5th year
Moore, K. The Developing Human

28. Further Vertebral Development
• Rib, Body and Vertebral Arch equivalents
Grey’s Anatomy

29. A Clarification of Terms
• Physeal Plate- Cartilage plate where growth occurs.
• Epiphysis- Area of bone on the end of the physeal plate that
contributes to longitudinal growth of a long bone
• Apophysis- An area of bone adjacent to a physeal plate that
does not contribute to longitudinal growth (Secondary Centers
of Ossification)

30. A Clarification of Terms
• Apophysis- An area of bone adjacent to a
physeal plate that does not contribute to
longitudinal growth (Secondary Centers of
Ossification)
Moore, K. The Developing Human

31. Recap Spinal Cord Development
Moore, K. The Developing Human

32. Recap Spinal Cord Development
• Neural tube-- CNS
• Neural Crests-- PNS and ANS
• Neural Canal– Ventricles and central canal
Moore, K. The Developing Human

33. Vertebral Column Development
Moore, K. The Developing Human

34. Where Things Go Wrong
• Failure of Canal to Close
Moore, K. The Developing Human

35. Where Things Go Wrong
• Failure of Canal to Close
Moore, K. The Developing Human

36. Where Things Go Wrong
CSF Flow/ Drainage Problems
Chiari malformations- (aka Arnold-Chiari)
definition- downward compression (not
traction) of the lower cerebellar contents into
the cervical region
Typed by amount of displacement-
-correlates with age of onset
-correlates with severity of symptoms
Shrek, H. The Cervical Spine

37. Where Things Go Wrong
CSF Flow/ Drainage Problems
Chiari malformations-
Type I
- mildest
- originally called adult onset
- caudal displacement of cerebellar tonsils
(with dentate ligaments, 4th ventricle, cervical
roots and brain stem in normal position.)
Shrek, H. The Cervical Spine

38. Where Things Go Wrong
CSF Flow/ Drainage Problems
Chiari malformations-
Type II
- more severe
- originally called congenital
- caudal displacement of cerebellar vermis, 4th
ventricle, medulla and lower pons
Shrek, H. The Cervical Spine

39. Where Things Go Wrong
CSF Flow/ Drainage Problems
Chiari malformations-
Type III
- most severe
- caudal displacement of cerebellum and brain
stem into high cervical meningiocele
Shrek, H. The Cervical Spine

40. Chiari Malformations con’t.
• Symptoms- due to neural compression at foramen magnum
– Lower cranial nerve dysfunction
– Long tract signs
• Associated with:
– Scarring
– Compressive atrophy
– Fibrous band
Shrek, H. The Cervical Spine

41. Chiari Malformations con’t.
• Bony deformity = Basilar Impression
– May be secondary to other conditions
– MCC- congenital anomaly in cerv-occ. Area
– Def.- upward movement of base of skull in the foramen magnum area
– Measured by intracranial extension of the tip of odontoid
Shrek, H. The Cervical Spine

42. Basilar Impression- measurement
• Chamberlain’s Line (Red)
– Hard palate to foramen magnum
– Odontoid below line +/- 4 mm.
Shrek, H. The Cervical Spine

43. Basilar Impression- measurement
• McRae’s Line (Green)
– AP of foramen magnum- odontoid below this line
– Symptoms when AP diameter <20 mm.
Shrek, H. The Cervical Spine

44. Basilar Impression- measurement
• Wackenheimer’s Line (Blue)
– Drawn along clivus
– Odontoid is ventral
Shrek, H. The Cervical Spine

45. Fixation +/- Position Changes
• Tethered Cord
– Cause unknown, probably multiple
– Assoc. with cutaneous lesion 54%
– Assoc. with lipoma 15%
– Female 2:1
– Slowly progressive motor dysfunction
– Recovery after surgery- poor- operate early!
Weinstein, S. The Pediatric Spine

46. Fixation +/- Position Changes
• Diastematomyelia
– Cord divided by fibrous, cartilagenous or bony septum
– Cutaneous lesion +/-
– Dural tube- one or two
– Diagnose before spinal instrumentation!
Weinstein, S. The Pediatric Spine

47. Multisystem Problems
• VATER/VACTERL
– V- vertebral anomalies/ dysgenesis, vascular
– A- anal atresia
– C- cardiac anomalies
– T- tracheo-eophageal (T-E) fistulas
– E- esophageal atresia
– R- renal anomalies
– L- limb anomalies, radial (forearm) dysplasia
– S- single umbilical artery
Weinstein, S. The Pediatric Spine

48. Segmentation Problems
• Hemivertebra- Segmented vs. non-segmented
(scoliosis lecture)
Weinstein, S. The Pediatric Spine

49. Segmentation Problems
• Failure of Segmentation (aka congenital fusions)
– Klippel-Feil Syndrome
• Short neck
• Low posterior hair line
• Limited cervical ROM
• Beware of compensatory hyper-mobility
• Familial component
• Assoc. with Fetal Alcohol Syndrome
Weinstein, S. The Pediatric Spine

50. Questions?
• Fellowship Trained
• Board Certified
• Experienced
• Diligent about the literature
• Second opinion
• rrooney@seattlespinegroup.com
Confidential