Impact of Platybasia and Anatomic Variance on Surgical Approaches to the Craniovertebral Junction

Objectives/Hypothesis: The aim of this study was to characterize the anatomic relation of the craniovertebral junction (CVJ) relative to the palatal line (PL), determine if the height of the CVJ over the PL is directly related to the anterior skull base (ASB) angle and the condition of platybasia, and consider the impact of the findings on endoscopic surgical approaches to the skull base. Study Design: Retrospective radiographic review. Methods: A retrospective study was performed using patients with chronic rhinosinusitis (CRS) as the control population and patients with platybasia as the study population. Sagittal magnetic resonance imaging and computed tomography were used to measure the ASB angle and the height of the CVJ above or below the PL. Results: The height of the CVJ relative to the PL is significantly higher in the platybasia group compared to the CRS group. However, a linear relationship is not identified between ASB angle and height of the CVJ relative to the PL. The height of the CVJ relative to the PL shows a wide distribution in both populations extending >1 cm above (platybasia group) and 1 cm below (control group). Conclusions: Platybasia results in a higher CVJ relative to the PL compared to the general population; however, the relationship is not linear. The wide distribution of the CVJ relative to the PL indicates that the approach selection must be tailored to the patient's specific anatomy.