Commentary on: "To the Occiput or Not? C1-C2 Ligamentous Laxity in Children with Down Syndrome".

Siemionow and Chou review the surgical management of atlantoaxial instability in the context of Down syndrome, using two interesting illustrative cases with different craniocervical abnormalities (atlantoaxial rotatory subluxation and os odontoideum). Both patients present with significant craniocervical spinal cord compression, and in this context, they highlight the specific case nuances that prompt occiptocervical fusion in one case and isolated atlantoaxial fixation in the other. However, it is important to note that while the authors refer to the presence of basilar invagination (and cranial settling) in these cases, a review of the accompanying radiographic images suggests that while significant craniocervical deformity and atlantoaxial instability is present, neither case truly has a diagnosis of basilar invagination nor cranial settling.