Dev Spine Peds PP Embryology Quick reference slides

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3 phases • Gastrulation/Notocord Integration 2 nd-3rd weeks • Two layer embryonic plate divides into three laters (ectoderm, mesoderm, endoderm) • Notocordal cells enter and extend cranially • Neuroenteric canal forms temporarily • Primary Neurulation 3 rd-4th weeks • Notochord interacts with overlying ectoderm, fusion to form the neural tube • Secondary Neurulation 5 th-6th weeks • Cells of Hensen’s node migrate caudally to presacral region • Retrogressive differentiation & Canalisation

EMBRYOLOGY

PRIMARY NEURULATION DEFECT OPEN SPINAL DEFECT OSD MYELOCELE, MYELOSCHISIS

The placode remains “flat” and meninges are deep to the bony defect

OPEN DEFECT, CHIARI II MYELOMENINGOCELE MMC

Placodr extends beyond the spinal defect, into a dilated cyst

TARTORI CLINICAL-RADIOLOGICAL CLASSIFICATION CLOSED SPINAL DEFECT CSD WITH MASS • Closed Spinal Dysraphism • CSD With Sub Q Mass • Lipomas with Dorsal Defect • Lipomyeloceles • Lipomyelomeningoceles • Meningoceles • Myelocystoceles • Cervical or Terminal

• Theories: • Anomaly of Primary Neurulation with Premature Disjunction

LIPOMYELOMENINGOCELE LIPOMA WITH DORSAL DEFECT CSD WITH (OR W/O) SUB Q MASS

Lipomyelocele

Lipomyelomeningocele

Key: The intrathecal fat associated with the low cord must be contiguous with the subcutaneous fat!

LMMC BENIGN TERATOMA?

ORIGINATING FROM TOTIPOTENTIAL CELLS OF HENSEN’S NODE

CSD WITHOUT MASS INTRADURAL/INTRASPINAL LIPOMA • • • • •

INTACT DURA • Fat is NOT contiguous with the subQ fat Dorsal surface cord 75% • Subpial, filling placode normal skin 2% syrinx “Lipoma with Dorsal Defect” • Bony spine may or may not be intact

TERMINAL MYELOCYSTOCELE CSD WITH SUBQ MASS • Rare, = Syringocele • Central cord canal expands thru spinal defect • Asstd terminal lipoma • more rarely, in association with a LMC/LMMC or Teratoma • Associated anomalies: • Imperforate, anus, ambiguous genitalia, vertebral segmentation anomalies • Hydrocephalus uncommon • poorer prognosis

SECONDARY NEURULATION CAUDAL DEDIFFERENTIATION • Normal Conus Position: • Conus ascends in canal due to faster spinal bone growth • 24 weeks L3 • 40 weeks inferior L2 • 3 months mid L2 >90%

Sacrococcygeal hypogenesis= caudal regression

DERMAL SINUS TRACT CSD, SIMPLE (OSD?) • Focal Non Disjunction • Epithelial lined tract • May have associated congenital tumors • Dermoid/ Epidermoid

GASTRULATION & NOTOCHORDAL FORMATION AND INTEGRATION Intercalation:

notochord fuses with endoderm > primitive neurenteric canal (communication between the central canal of notochord and the yolk sac)

SECONDARY NEURULATION CAUDAL DEDIFFERENTIATION CAUDAL REGRESSION ANOMALIES

VACTERL

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Vertebral anomalies

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Anorectal atresia

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Cardiac

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TE fistula

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Renal

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Limb anomalies

SC TERATOMA • Classification

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– Type I

Better prognosis (decreased incidence of malignancy) if:

– Type II

• Cystic

• External 47% • External>Internal 35%

– Type III

• Internal>External 8%

– Type IV

• Presacral 10%

• Extrapelvic