Atlanto-occipital assimilation

Dr Francis Fortin and Dr Henry Knipe et al.

Atlanto-occipital assimilation is the fusion of the atlas (C1) to the occiput and is one of the transitional vertebrae

Atlanto-occipital assimilation occurs in approximately 0.5% (range 0.25-1%) of the population 2-4

It is typically asymptomatic but symptoms from nerve or vascular compression can occur. 

Fusion of C1 to the occiput can be either 3:

  • complete: C1 not identifiable
  • incomplete: C1 partially identifiable

Atlanto-occipital assimilation is associated with 2:

Anatomy: Spine
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Article information

rID: 28434
Section: Anatomy
Synonyms or Alternate Spellings:
  • Atlantooccipital fusion
  • Atlanto-occipital fusion
  • occipitalization

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Cases and figures

  • Case 1
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  • Case 2
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  • Case 3: with C2-C3 fusion
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  • Case 4
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