Atlanto-occipital assimilation

Changed by Henry Knipe, 25 Mar 2014

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Atlanto-occipital assimilation is the fusion of C1the atlas (C1) to the occiput and is one of the transitional vertebrae.

Epidemiology

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

Gross anatomy

~~Fusion of C1 to the occiput can be either complete (C1 not identifiable) or incomplete (C1 partially identifiable)~~ ³.

PathologyClinical presentation

Atlanto-occipital is typically asymptomatic but symptoms from nerve or vascular compression can occur.

Gross anatomy

Fusion of C1 to the occiput can be either ³:

complete - C1 not identifiable
incomplete - C1 partially identifiable

Associations

Atlanto-occipital assimilation is associated with ²:

fusion of C2 and C3 ~~(50~~(occurs in 50% of cases)
basilar invagination
cleft palate
cervical ribs
urinary tract anomalies

-<p><strong>Atlanto-occipital assimilation</strong> is the fusion of C1 to the occiput and is one of the <a href="/articles/transitional-vertebra">transitional vertebrae</a>. </p><h4>Epidemiology</h4><p>Atlanto-occipital assimilation occurs in 0.25-1% of the population <sup>2-4</sup>. </p><h4>Gross anatomy</h4><p>Fusion of C1 to the occiput can be either complete (C1 not identifiable) or incomplete (C1 partially identifiable) <sup>3</sup>. </p><h4>Pathology</h4><p>Atlanto-occipital is typically asymptomatic but symptoms from nerve or vascular compression can occur. </p><h5>Associations</h5><p>Atlanto-occipital assimilation is associated with <sup>2</sup>:</p><ul>
~~-<li>fusion of C2 and C3 (50%)</li>~~
+<p><strong>Atlanto-occipital assimilation</strong> is the fusion of the <a title="atlas" href="/articles/atlas">atlas</a> (C1) to the occiput and is one of the <a href="/articles/transitional-vertebra">transitional vertebrae</a>. </p><h4>Epidemiology</h4><p>Atlanto-occipital assimilation occurs in ~0.5% (range 0.25-1%) of the population <sup>2-4</sup>. </p><h4>Clinical presentation</h4><p>Atlanto-occipital is typically asymptomatic but symptoms from nerve or vascular compression can occur. </p><h4>Gross anatomy</h4><p>Fusion of C1 to the occiput can be either <sup>3</sup>:</p><ul>
+<li>
+<strong>complete</strong> - C1 not identifiable</li>
+<li>
+<strong>incomplete</strong> - C1 partially identifiable</li>
+</ul><h5>Associations</h5><p>Atlanto-occipital assimilation is associated with <sup>2</sup>:</p><ul>
+<li>fusion of <a title="C2" href="/articles/axis-c2">C2</a> and C3 (occurs in 50% of cases)</li>
~~-<li>cleft palate</li>~~
+<li><a title="Cleft palate" href="/articles/cleft-palate">cleft palate</a></li>

Images Changes:

Image 3 CT (bone window) ( update )

Caption was changed:

Case 3: with C2-C3 fusion

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