41 - Pterion Variation: Investigating Inheritance, Cranial Shape and Pathology in the Cayo Santiago Rhesus Macaques

Poster Board Number: 41
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Abstract Body : The pterion is an important neurosurgical landmark where the frontal, parietal, sphenoidal and temporal bones meet. Variation of pterion configurations, such as sphenoido-parietal contact and temporo-frontal contact (TF), present additional challenges to already high-risk craniotomy procedures. Several factors have been hypothesized to determine pterion configurations, such as, familial inheritance, neurocranial growth, as well as the influence of sutural closure. Yet few studies have examined why pterion configuration varies and those that have do so with little familial context. This study investigates 1212 individual Rhesus macaque crania, with known sex, age, and pedigree information, in the derived skeletal collection from monkeys lived at Cayo Santiago, to explore causes of pterion variation. Matrilineal relationships, cranial height/length, and those with confirmed craniosynostosis were examined as potential influences. Results demonstrated that there are significant differences in the prevalence of non-TF configurations, ranging from 3.84% to 51.28%, between matrilineal families (Fishers exact p value = 0.034). No relationship was found between pterion configuration and cranial height/length (t = 1.62; p = 0.105). Furthermore, those with craniosynostosis all exhibited the standard TF configuration. These finding suggests that familial inheritance, but not growth or pathology, most probably influences the pterion configuration. The knowledge of pterion configurations and their variation mechanisms is not only useful in the study of skull development and evolution, but also in neurosurgical plannings. This represents the largest collation of pterion patterns in a single nonhuman population to date, and is a useful model for future studies exploring potential genetic bases.