Surgical Relevance of Pediatric Anterior Clinoid Process Maturation for Anterior Skull Base Approaches.

Background: Removal of the anterior clinoid process (ACP) can expand anterior skull base surgical corridors. ACP development and anatomical variations are poorly defined in children.

Objective: To perform a morphometric analysis of the ACP during pediatric maturation.

Methods: Measurements of ACP base thickness (ACP-BT), midpoint thickness (ACP-MT), length (ACP-L), length from optic strut to ACP tip (ACP-OS), pneumatization (ACP-pneumo), and the presence of an ossified carotico-clinoid ligament (OCCL) or interclinoid ligament (OIL) were made from high-resolution computed-tomography scans from 60 patients (ages 0-3, 4-7, 8-11 12-15, 16-18, and >18 yr). Data were analyzed by laterality, sex, and age groups using t-tests and linear regression.

Results: There were no significant differences in ACP parameters by laterality or sex, and no significant growth in ACP-BT or ACP-MT during development. From ages 0-3 yr to adult, mean ACP-L increased 49%, from 7.7 to 11.5 mm. The majority of ACP-L growth occurred in 2 phases between ages 0-3 to 8-11 and ages 16-18 to adult. Conversely, ACP-OS was stable from ages 0-3 to 8-11 but increased by 63% between ages 8-11 to adult. Variations in ACP morphology (OCCL/OIL/ACP-pneumo) were found in 15% (9/60) of scans. OCCL and OIL occurred in patients as young as 3 yrs, whereas ACP-pneumo was not seen in patients younger than 11 yrs.

Conclusion: The ACP demonstrates stable thickness and a complex triphasic elongation and remodeling pattern with development, the understanding of which may facilitate removal in patients <12. Clinically relevant ACP anatomic variations can occur at any age.