Anatomy of the Anterior Clinoid Process in Human Fetuses

Purpose The main objective of this study was to display the morphologic properties of the anterior clinoid process (ACP) in human fetuses in term of early childhood surgeries. Methods Twenty-four (10 females and 14 males) fetal cadavers aged from 16th to 28th weeks of gestation (at mean, 21.54 ± 3.11 weeks) were included in the present study. The dimensions of ACP were measured with a digital image analysis software. Results Taking into account the length, width, and angle of ACP, it was classified as Type 1 in 20.83% (10 cases), Type 2 in 10.42% (5 cases), Type 3 in 10.42% (5 cases), Type 4 in 2.08% (1 case), Type 5 in 8.33% (4 cases), Type 6 in 16.67% (8 cases), Type 7 in 8.33% (4 cases), and Type 8 in 22.92% (11 cases). According to the attachment site of the optic strut (OS) relative to ACP, OS was identified as the anterior 3/5 in 16.67% (8 cases), anterior 4/5 in 68.75% (33 cases), and posterior 1/5 in 14.58% (7 cases). Neither right-left nor male-female significant differences were observed between the quantitative values belonging to ACP and OS. Conclusion The percentage of the most complex and challenging type of ACP (the long, narrow, and narrow-angled ACP) in fetuses was found to be close to adults. Thus, routine adult surgical procedures such as anterior clinoidectomy might be successfully used in young children and infants. The attachment site of OS relative to ACP in adults was more anterior according to fetuses probably due to postnatal development such as the pneumatization of the sphenoid bone. In this regard, for pediatric neurosurgeons to avoid iatrogenic injuries and to select appropriate surgical approaches, further studies conducted on the attachment of OS relative to ACP in children are needed.