Prevalence and Morphometry of Occipital Condylar Canals and Their Surgical Relevance

Occipital condylar canals (OCCs) and associated condylar emissary veins contribute to brain thermoregulation, waste clearance, and venous outflow, particularly in an upright posture, supporting intracranial pressure regulation and cerebral homeostasis. When present, OCCs are critical landmarks in posterolateral skull base approaches, including the far lateral and transcondylar surgical routes. Their identification is useful for avoiding neurovascular injury during craniovertebral junction procedures. Despite their potential surgical relevance, the variability in OCCs (presence, associated symmetry or asymmetry, and morphometry) remains poorly documented. This study aimed to provide a detailed identification analysis of the inconsistent OCCs [the posterior condylar canals (PCCs) and paracondylar canals (PCs)], emphasizing their morphometry to enhance applied anatomic knowledge and improve surgical planning.

A total of 113 dried adult European skulls were examined at the National and Kapodistrian University of Athens to determine the prevalence of PCCs and PCs. When present, morphometric evaluations were performed according to laterality using metal wire probes to confirm patency. The prevalence of presence and absence was recorded based on laterality. All variables were additionally analyzed by sex, and significance was assessed using Fisher's exact test (P < .05).

PCC was identified in 74.3% of the specimens (bilateral, 44.2%; unilateral left-sided, 13.3%; and unilateral right-sided, 16.8%). Females showed a higher prevalence of PCC (80%) than males (58.6%). PC was observed in 9.7% of specimens. In the authors' experience, when present, the PCC and the corresponding condylar emissary veins served as useful anatomic landmarks during the far-lateral approach.

This study highlights the anatomic variability and surgical relevance of the PCC, PC, and their emissary veins. Though not consistently reliable landmarks, their identification and variation assessment may aid preoperative planning and intraoperative safety by reducing bleeding risk and preserving craniovertebral junction stability.