Foramen caecum canal: a potential anatomical pathway with clinical implications

The foramen caecum of frontal bone (FC) is traditionally described as a conduit between the extracranial and intracranial venous systems, potentially transmitting venous flow through a structure known as the vein of the foramen caecum (VFC). However, the existence and anatomical characteristics of this venous pathway remain controversial. This study aimed to evaluate the radiological presence of the foramen caecum canal (FCC) - a structural pathway through which such a vein could potentially course - using paranasal sinus computed tomography (CT) scans.

A retrospective review was conducted on 1,147 paranasal CT scans obtained from patients presenting with headache or sinusitis symptoms between 2010 and 2015. Scans were assessed for the presence of a continuous tubular structure extending from the crista galli to the nasal bone or prenasal soft tissues. Statistical comparisons were performed using Fisher's Exact test and Student's t-test.

Among 1,147 evaluated patients (616 males, 531 females; mean age: 44.38±14.89 years), a tubular structure consistent with the FCC was identified in 52 cases (4.5%). No significant differences in FCC presence were observed based on sex or age (p = 0.887 and p = 0.103, respectively). Most of the identified channels were continuous and well-defined on imaging.

This study identified a canal-like structure consistent with the anatomical course of the FCC in 4.5% of CT scans, supporting the structural presence of this transosseous passage in a subset of individuals. Although contrast-enhanced imaging was not used and venous content could not be confirmed, the identification of a continuous osseous canal indicates its structural presence; functional patency remains undetermined. Further multimodal and anatomical studies are warranted to clarify its prevalence, patency, and significance, particularly in relation to infection spread and surgical planning.