Osseous Bridges of the Sphenoid Bone: Frequency, Bilateral and Sex Distribution

SIMPLE SUMMARY: The sphenoid bone occupies the central part on the skull base and forms the floor of the middle cranial fossa where some important foramina-transmitting neurovascular structures are placed. Usually, there are few ligamentous connections between definite parts of the sphenoid bone, which occasionally may be replaced by bone formations. These bone bridges form additional foramina, which could compress the passing neurovascular structures. Sphenoid bridges also have a significant impact on the regional neurosurgery since they obstruct the surgical corridors to some regions of the skull base. In this study we investigate the frequency, bilateral and sex distribution of the different types of sphenoid bridges in Bulgarians. The obtained results show that the osseous bridges of the sphenoid bone are relatively common findings in the investigated series. This should be kept in mind during diagnostic and subsequent treatment of some conditions, which could be induced or related to the replacement of usual ligaments of the sphenoid bone with osseous bridges. ABSTRACT: Sellar (caroticoclinoid and interclinoid), pterygospinous and pterygoalar bridges are osseous bars of the sphenoid bone, which enclose additional foramina in the skull base and could cause entrapment of nerves, occlusion of vessels and obstruction of surgical corridors. This study aimed to investigate the frequency of sphenoid bone bridges in Bulgarians and to assess the bilateral and sex differences in their distribution. This study was performed on head CT scans of 315 Bulgarians, 148 males and 167 females. The sellar bridges were the most common type of sphenoid bridging; particularly the caroticoclinoid bridge. The pterygospinous bridge was a relatively common finding and the pterygoalar bridge was the most infrequent type of bridging. The total frequency of sellar bridges did not differ significantly between both sides and sexes. The pterygospinous bridge did not indicate significant bilateral differences but showed considerable sex differences concerning the left-side occurrence, which was significantly higher in the male series. There were no considerable bilateral and sex differences in the distribution of the pterygoalar bridging. There were no significant correlations between the different types of sphenoid bone bridges, but each type of bridging showed significant positive correlations between the right and left side co-occurrence in males and females.