embryology and developmental pathology

Spinal Embryology and Developmental Pathology

Richard C Rooney, MD, FACSrrooney@seattlespinegroup.com

Stages of Neural-Spinal Development- First Week

Moore, K. The Developing Human

Stages of Neural-Spinal Development- Second Week

Moore, K. The Developing Human

Stages of Neural-Spinal Development- Third Week

• Primitive Streak

Moore, K. The Developing Human

Stages of Neural-Spinal Development- Third Week

• Primitive Streak

Moore, K. The Developing Human

Stages of Neural-Spinal Development- Third Week• Notochord

Moore, K. The Developing Human

Stages of Neural-Spinal Development- Third Week• Notochord

Stages of Neural-Spinal Development- Third Week• Notochord

Stages of Neural-Spinal Development- Third Week• Notochord

Stages of Neural-Spinal Development- Third Week• Notochord

Stages of Neural-Spinal Development- Third Week• Notochord

Stages of Neural-Spinal Development- Third Week• Notochord

Moore, K. The Developing Human

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

Stages of Neural-Spinal Development- Third Week• Somites

Moore, K. The Developing Human

Stages of Neural-Spinal Development- Third Week• Mesoderm

Stages of Neural-Spinal Development- Third Week• Neural Plate

Moore, K. The Developing Human

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

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

Stages of Neural-Spinal Development- Fourth Week

• Somites- divide into dense and sparse areas

Moore, K. The Developing Human

Stages of Neural-Spinal Development- Fourth Week

• Centrum- dense portion of cephalad with sparse portion of caudal somite

Moore, K. The Developing Human

Primodial Vertebral Segment

Bullough, Atlas of Spinal Diseases

Vertebral Development

Bullough, Atlas of Spinal Diseases

Vertebral Development

Bullough, Atlas of Spinal Diseases

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

Stages of Neural-Spinal Development- Fifth Week

• Vertebrae- Mesenchymal model finished

Moore, K. The Developing Human

Stages of Neural-Spinal Development- Sixth Week

• Vertebrae- – Chondrification- 6th week– Ossification Centers- 7th week

Moore, K. The Developing Human

Further Vertebral Development• Neural Central Joint- fuses 3rd to 6th year• Vertebral Arch- fuses 3rd to 5th year

Moore, K. The Developing Human

Further Vertebral Development

• Rib, Body and Vertebral Arch equivalents

Grey’s Anatomy

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)

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

Recap Spinal Cord Development

Moore, K. The Developing Human

Recap Spinal Cord Development• Neural tube-- CNS• Neural Crests-- PNS and ANS• Neural Canal– Ventricles and central canal

Moore, K. The Developing Human

Vertebral Column Development

Moore, K. The Developing Human

Where Things Go Wrong

• Failure of Canal to Close

Moore, K. The Developing Human

Where Things Go Wrong• Failure of Canal to Close

Moore, K. The Developing Human

Where Things Go WrongCSF 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

Where Things Go WrongCSF 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

Where Things Go WrongCSF 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

Where Things Go WrongCSF 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

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

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

Basilar Impression- measurement• Chamberlain’s Line (Red)

– Hard palate to foramen magnum– Odontoid below line +/- 4 mm.

Shrek, H. The Cervical Spine

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

Basilar Impression- measurement• Wackenheimer’s Line (Blue)

– Drawn along clivus– Odontoid is ventral

Shrek, H. The Cervical Spine

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

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

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

Segmentation Problems• Hemivertebra- Segmented vs. non-segmented

(scoliosis lecture)

Weinstein, S. The Pediatric Spine

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

Questions?

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

Confidential