C-Spine

Atlantoaxial Instability

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Atlantoaxial Instability

  • See Also
  1. Atlantoaxial Rotary Fixation
  • Epidemiology
  1. Incidence: 15% of Down Syndrome age <21 years old
  2. Congenital atlantoaxial defects also seen in Congenital Dwarfism, odontoid hypoplasia
  • Symptoms suggestive of Atlantoaxial Instability
  1. Gait disturbance
  2. Spasticity
  3. Change in bowel or Bladder function
  • Signs suggestive of Atlantoaxial Instability
  1. Neck Pain
  2. Torticollis
  3. Motor weakness in upper or lower extremities
  4. Increased Deep Tendon Reflexes
  5. Babinski response
  6. Clonus
  1. Indications
    1. Routine screening at age 5-6 no longer recommended
    2. Xray indicated for Signs or symptoms above
    3. Screen prior to Contact Sport participation
  2. Views
    1. Neutral
    2. Flexion
    3. Extension
  3. Interpretation
    1. Measure C1-C2 space
      1. Posterior segment of anterior arch of C1
      2. Anterior segment of odontoid process of C2
    2. Distance should be no more than 5 mm
  • Prognosis
  1. Precludes Contact Sport participation if present
  • References
  1. Frost (1999) Clin Neuropathol 18(5):250-9 [PubMed]
  2. Msall (1990) Pediatrics 85:447-9 [PubMed]
  3. Pueschel (1987) Pediatrics 80:555-60 [PubMed]