Neurosurgery notes/Paediatrics/Developmental abnormalities/Spinal anomalies

Spinal anomalies

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Parent item
Developmental abnormalities
Sub-item
Klippel-Feil Syndrome
Spinal Bifida
Neurenteric Cyst
Congenital Lumbosacral Lipomas
Dermal sinus tracts
Myelocystocele
Tethered Cord Syndrome (TCS)
Lumbosacral Nerve Root Anomalies
Achondroplasia
Segmental Spinal Dysgenesis (SSD)
Sacral Dimple

General

  • Dysraphism = incomplete fusion

Various classification

Lemire classification (embryological classification)

Gastrulation disorder

  • Notes: Trilaminar disc formation, abnormalities will be ventrally placed and involved all layers of germ cell (skeletal anomalies are common)
  • Split cord malformation (Formation of accessory neuroenteric canal)
    • Diastematomyelia
    • Diplomyelia
  • Neurenteric cysts
    • Persistence of neurenteric canal of kovalevsky
  • Klippel-Feil syndrome
  • Dermoid, Epidermoid cyst

Neurulation defects

  • Notes: non-closure of the neural tube results in open lesions
Primary neurulation disorder
  • Craniorachischisis:
    • Total dysraphism
    • Many die as spontaneous abortion
  • Disjunction disorder
      • Non disjunction
        • Myelomeningocele
          • Open Neutral tube defects
            • Due to disruption of the infolding of the neural plate to form the neural tube → overlying mesodermal and ectodermal elements fail to form → open spinal defect
            • Neuro placode: Disruptions of the infolding process of neural plate into neural tube causes a persistent neural plate
        • Meningocele
        • Myeloschisis
      notion image
Junctional disorder
  • Spinal lipomas Type 2 (Lipomyelomeningocele)
Secondary Neurulation disorder (ONLY CONDITION where the spinal cord terminates high)
  • Spinal lipomas
    • Type 3: Lipomyelomeningocele
    • Type 4
  • Dermal sinus tract

Postneurulation defects

  • Notes: Produces skin-covered (AKA closed) lesions (some may also be considered “migration abnormalities”; see below)
  • Spinal
    • hydromyelia/syringomyelia

Dysraphism

Type
Description
Stage Affected
Open spinal dysraphism
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Myelomeningocele
Defect in dura, posterior vertebral elements, facia and skin causing the neural placode to be exposed in the midline
Primary neurulation
Myelocele
As myelomeningocele, but subarachnoid space ventral to placode is not expanded resulting in a lesion flush with skin
Hemimyelocele
Myelocele affecting one of two hemicords in split cord malformation
Gastrulation and primary neurulation
Hemimyelomeningocele
Myelomeningocele affecting one of two hemicords in split cord malformation
Closed spinal dysraphism with subcutaneous mass
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Lipomyelomeningocele
A subcutaneous lipoma tethers the spinal cord (lipoma-placode interface) outside the spinal canal via defect in vertebral elements
Primary neurulation
Lipomyelocele
A subcutaneous lipoma tethers the spinal cord (lipoma-placode interface) inside the spinal canal via defect in vertebral elements
Meningocele
Posterior—Herniation of CSF-filled meningeal sac through posterior bony defect (may contain nerve roots but not spinal cord). Dura may have defect but overlying skin is intact. Anterior meningoceles are part of the caudal regression syndrome
Unknown
Terminal myelocystocele
Expansion of terminal central canal (syringocele) surrounded by a meningocele with no communication between two components. Syringocele is caudal to the meningocele and herniates through a wide spina bifida to cause a intergluteal cystic swelling
Secondary neurulation and retrogressive differentiation
Closed spinal dysraphism without subcutaneous mass
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Simple dysraphic state
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Posterior spina bifida
Simple defect of fusion of posterior neural arch of a vertebra, usually at L5 or S1
Intradural lipoma
Lipomas originate from early disjunction between neuroectoderm and ectoderm
Primary neurulation
Filum terminale lipoma
Fibrolipomatous thickening of the filum terminale
Secondary neurulation and retrogressive differentiation
Tight filum terminale
A short thick filum (> 2 mm without fat), which impairs the ascent of conus medullaris.
Persistent terminal ventricle
Small ependymal lined cavity in the conus medullaris which may undergo cystic dilatation
Complex dysraphic state
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Split cord malformation
Type 1—bony midline septum dividing cord into two separate cords in own dural sleeves
Type 2—single thecal sac containing split cords with an intervening fibrous band
Gastrulation (notochordal integration)
Neuroenteric cyst
Cysts usually in intradural extramedullary plane of endodermal origin, usually lined with GI or respiratory epithelium
Dorsal enteric fistula
Most severe. Cleft connecting the bowel with dorsal skin surface through the prevertebral soft tissues, split vertebral bodies and spinal cord, neural arch, subcutaneous tissue
Dermal sinus
Epithelium-lined fistula which extends from skin to meninges within the spinal canal, possibly opening into the subarachnoid space or connecting to filum terminale, lipoma and may also be associated with a spinal dermoid
Caudal regression syndrome
Agenesis of spinal column, imperforate anus, genital anomalies, bilateral renal dysplasia, pulmonary hypoplasia and lower limb abnormalities. Syndromic associations include OEIS, VACTERL and Currarino triad
Gastrulation (notochordal formation)
Currarino triad
sacral agenesis abnormalities anorectal malformation presacral mass consisting of teratoma, anterior sacral meningocele or both
VACTERL
V - Vertebral anomalies-Congenital scoliosis
A - Anorectal malformations
C - Cardiovascular anomalies
T - Tracheoesophageal fistula
E - Esophageal atresia
R - Renal (Kidney) and/or radial anomalies
L - Limb defects
Segmental dysgenesis
Segmental agenesis of thoracolumbar spine: vertebral, segmental spinal cord hypoplasia/aplasia with caudal bulkiness, congenital paraparesis, lower limb deformities