It is feasible to place PALMS using the described technique. CT angiography is of crucial importance for preoperative planning using the described special reconstructions. The arch posterior to the lateral mass (APLM) is defined as the bone stock situated posterior to the lateral mass, respecting its convergence. The ideal entry point for a PALMS is on the APLM above the center of the converging lateral mass. A complete or incomplete ponticulus posticus and a retrotransverse foramen or groove can be used as an accessory landmark to refine the entry point.

In our case, occipitalization considerably changed the anatomy of the upper cervical spine and craniocervical junction. Special care must be taken when using the posterior approach to avoid neurovascular injury in cases with occipitalization.

Using this approach, it was possible to reach the posterior aspect of C1 and C2; the relevant anatomy needed to perform a C1-C2 fusion could be well visualized.