Pseudospread of the atlas

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Pseudospread of the Atlas 1

• Defined: > 2 mm total overlap of the two C1 lateral masses on C2 on AP open- mouth view.
• Prevalence: 91-100% during second year of life
  • Youngest: 3 months
  • Oldest: 4 years
  • 2mm during first year.
  • 4mm during the second.
  • 6mm during the third.
  • Decreases after that.
  • Max is 8m
• Trauma is not a contributing factor
• Neck rotation can stimulate the appearance of a Jefferson fracture.
• Probably a result of disproportionate grown of the atlas on the axis. 'Misdiagnosed as JEFFERSON FRACTURE.'
  • Rarely occurs prior to teen years.

Recommendation:

• If suspicion for fracture is high: CT scan through C1 can resolve the issue.

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1. Suss RA, Zimmerman RD, Leeds NE. Pseudospread of the atlas: False sign of jefferson fracture in young children. AJR Am J Roentgenol. 1983;140:1079-1082

-edaks