II. Epidemiology

  1. Incidence: 15% of Down Syndrome age <21 years old
  2. Congenital atlantoaxial defects also seen in Congenital Dwarfism, odontoid hypoplasia

III. Symptoms suggestive of Atlantoaxial Instability

  1. Gait disturbance
  2. Spasticity
  3. Change in bowel or Bladder function

IV. 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

V. Radiology: C-Spine XRay

  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
    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

VI. Prognosis

  1. Precludes Contact Sport participation if present

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Related Studies

Ontology: Atlantoaxial instability (C0410653)

Concepts Disease or Syndrome (T047)
SnomedCT 202820009
Italian Instabilità atlantoassiale
Japanese 環軸椎不安定, カンジクツイフアンテイ
Czech Atlantoaxiální instabilita
English atlantoaxial instability, Atlantoaxial instability, Atlantoaxial instability (disorder)
Hungarian Atlantoaxialis instabilitás
Spanish inestabilidad atloaxoidea (trastorno), inestabilidad atloaxoidea, Inestabilidad atloaxoidea
Dutch atlanto-axiale instabiliteit
French Instabilité atlantoaxiale
Portuguese Instabilidade atlantoaxial
German atlantoaxiale Instabilitaet