Surgical Anatomy and Morphometric Analysis of the Optico-Chiasmatic Apparatus, Optic Canal and Sphenoid Ridge

Abstract

Summary: An anatomical study was performed in order to obtain help for orientation regarding the cranial base approaches to the anterior cranial base. Cranial base approaches were studied in 8 adult cadaver heads, and morphometric measurements critical in these approaches were achieved in 76 dry skulls. Importance of the surgical anatomy of the opticochiasmatic apparatus, optic canal, sphenoid ridge, and anterior clinoid was emphasised in this study. Observations from the dissections and operative approaches, and measurements between various points were recorded in a specifically designed software, and these data helped both to understand the local anatomy and the relationship to the intimate structures better and to decide the head position, the degree and direction of safe bony removal, and the direction of the operative approach during the surgery. Considerations important in the selection of these structures, anatomical landmarks and distances were discussed.

Evaluation of the Cranial Aperture of the Optic Canal on Cone-Beam Computed Tomography Images and its Clinical Implications for the Transcranial Approaches

“…However, our Ang-in-SP value was evidently smaller than the adult (mean data range: 10.27°-18.20°) and pediatric (average data: 16.01°) values in the previous studies (Supplementary Digital Content, Table 5, http://links.lww.com/SCS/D893). 22,42,46 Ten et al 22 observed that this angle decreased in children (infancy group: 24.87°± 5.74°, early childhood group: 20.80°± 6.40°, late childhood group: 15.67°± 4.87°, prepubescence group: 13.86°± 5.13°, postpubescence group: 12.81°± 5.53°). They found that the angle in adolescents was almost half that of infancy.…”

“…Our Ang-in-AP value was compatible with the adult (mean data range: 29.56°-45.32°) and pediatric (mean data range: 39.28°-39.50°) values in the previous studies (Supplementary Digital Content, Table 5, http:// links.lww.com/SCS/D893). 22,32,33,39,[42][43][44][45][46][47][48] Ten et al 22 determined that Ang-in-AP in infants was significantly greater than that in the other pediatric age groups, but it did not change after infancy period. However, our Ang-in-SP value was evidently smaller than the adult (mean data range: 10.27°-18.20°) and pediatric (average data: 16.01°) values in the previous studies (Supplementary Digital Content, Table 5, http://links.lww.com/SCS/D893).…”

“…Our Dis-to-MSL value was evidently smaller than adult (mean data range: 6.48-7.64 mm) and pediatric (average data: 7.17 mm) values in the literature (Supplementary Digital Content, Table 5, http://links.lww.com/SCS/ D893). 22,33,42,46,48 Similar to Dis-to-AB, different landmark selection may have triggered this difference. Ten et al 22 determined that Dis-to-MSL did not change after late childhood period.…”

“…On the other hand, our Dis-to-AB value was evidently greater than adult (mean data range: 44.38-50.94 mm) and pediatric (average data: 54.04 mm) values in the literature (Supplementary Digital Content, Table 6, http://links.lww.com/SCS/D894). 22,[24][25][26]31,46,49 We think that the reason for this difference is due to different landmark selection (Supplementary Digital Content, Table 6, http://links.lww.com/SCS/D894). Ten et al 22 4, http://links.lww.com/ SCS/D892).…”

“…On the other hand, our Dis-to-AB value was evidently greater than adult (mean data range: 44.38–50.94 mm) and pediatric (average data: 54.04 mm) values in the literature (Supplementary Digital Content, Table 6, http://links.lww.com/SCS/D894). 22,24–26,31,46,49 We think that the reason for this difference is due to different landmark selection (Supplementary Digital Content, Table 6, http://links.lww.com/SCS/D894). Ten et al 22 observed that the orbital depth (ie, the Dis-to-AB) increased proportionally in children (infancy group: 44.15 ± 2.51 mm, early childhood group: 49.85 ± 2.96 mm, late childhood group: 53.22 ± 2.64 mm, prepubescence group: 55.68 ± 2.93 mm, postpubescence group: 58.20 ± 3.05 mm).…”