GeneFacts

Thursday, Dec 18th

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Diagnosis

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Diagnostic Testing and Evaluation

Diagnosis is typically established by imaging modalities, but biochemical testing can be helpful prenatally.

Diagnostic Criteria

An imaging study that demonstrates spina bifida

First Steps

Prenatally

  • Measure/check MSAFP at 15-20 weeks.
  • AFP can be normal in 15-20% of cases of spina bifida
  • MSAFP can also be elevated in ventral wall defects and multiple gestations
  • Ultrasound
  • Amniotic fluid AFP measurement

Postnatally

  • Physical examination
  • Sacral dimple/fat collection/hair tuft/birthmark overlying defect (spina bifida occulta)
  • Fluid-filled sac (meningocele)
  • Exposed spinal cord and meninges (myelomeningocele)
  • Imaging of the spine
  • X-ray, ultrasound, CT or MRI

Testing Strategy

  • If screening test or physical exam is suggestive, obtain ultrasound or other imaging test to confirm the diagnosis.

Tests that are NOT helpful

  • Maternal serum folate level - spina bifida can occur with normal levels due to other predisposing factors
  • MTHFR genotyping - does not affect management, unclear contribution at the individual level

Subsequent Evaluation

  • Increased risk for Chiari II malformation,
  • Consider head imaging if suggestive signs and symptoms, including visual disturbance, facial numbness, stridor, neck pain, and respiratory compromise exist
  • 90-95% of myelomeningocele are affected with Chiari II malformation
  • Increased risk for vertebral anomalies causing defects such as tethered cord syndrome, syringomyelia, and diastemetomyelia.

Lifestyle/Environmental Contributors to Disease

Prenatal exposures

  • X-irradiation
  • Hyperthermia [rare]
  • Drugs
  • Valproic Acid - 10-fold increase in risk
  • Carbamazepine
  • Maternal metabolic conditions
  • Folic acid deficiency
  • Diabetes Mellitus

Postnatal factors that exacerbate the condition

  • Obesity/metabolic syndrome
  • Osteopenia
  • Infection
  • Comorbidities
  • Substance abuse
  • Depression

Differential Diagnosis

  • Spinal tumors (dermoids, lipomas, and teratomas)
  • Spinal cord infarction
  • Progressive spastic paraparesis
  • Multiple sclerosis (in adults if limited to the spinal cord)

Consensus Statements and Guidelines

US Preventive Services Task Force recommendation statement

American Academy of Pediatrics

American College of Obstetricians and Gynecologists (ACOG)

American Academy of Family Physicians

American College of Medical Genetics