Anatomical and clinical correlates of the precondylar tubercle
Jaffar, A. A.
Abstract
Introduction: The possible presence of the precondylar tubercle should be considered in order to avoid misinterpretation in radiographic images and confusion during surgical intervention. This study is aimed to describe and report the frequency of the precondylar tubercle and similar variations at the anterior margin of foramen magnum in order to alert the clinical community of their presence and of the possible associated variations. Materials and Methods: Fifty dry skulls were examined for variations at the anterior margin of foramen magnum. One skull with bilaterally prominent precondylar tubercles was studied using a spiral computerized tomography in order to demonstrate the radiographic appearance of the tubercle. Results: Precondylar tubercles were observed in 10% of the skulls. Other simulating observations included the presence of a midline spur, bilateral depression anteromedial to the occipital condyles, third occipital condyle, and a partly divided occipital condyle. In 89% of the cases these variations were associated with septation of the hypoglossal canal. Conclusion: The presence of a mere precondylar tubercle is not expected to produce neurological manifestations. However, its possible association with other variations should be considered. The size and location of the precondylar tubercle might evade plain radiographic films, but it can be readily revealed in axial computerized tomograms.