Anatomical analysis on the lateral bone window of the sella turcica: a study on 530 adult dry skull base specimens

Abstract

Objective: To investigate the morphometric characteristics of the lateral bone window (LBW) of the sella turica.

Methods: A descriptive anatomical study of LBW was performed in 530 cases of dry skull base specimens with relatively complete sella turcica. Detailed morphometric characteristics such as dimensions and classification of the LBW was studied. All data analysis was performed using SPSS 17.0 statistical software.

Results: LBW is located in the lateral bony structures of sella turcica. The mean area sizes of the LBW were 75.99 ± 25.81 mm(2) (left) and 76.00 ± 25.53 mm(2) (right). There was no significant difference and there was a ​​good positive correlation between bilateral areas of the LBWs. The area size of the LBWs is graded as follows: Grade A (< 60 mm(2)), B (60~90 mm(2)) and C (> 90 mm(2)). LBW morphology was typed as follows: Type I, II, III, IV. And Tpye III includes Type IIIa and IIIb; Type IV includes Type IVa, IVb, IVc, IVd.

Conclusions: The lateral bone window of sella turcica is an important structure located between pituiary fossa and parasellar region. The morphological measurements and variations of LBW in this study will provide preliminary data for further anatomical study of sella turcica. Moreover, knowing detailed anatomy of this region is essential for neurosurgeons who make surgery on cranial base or for teaching about the sella turcica in the neuroanatomy lab.

Keywords: Anatomy; Clinical significance; Clinoid process; Lateral bone window; Sella turcica; Sella turcica bridge.

Figure 1

The procedure used to calculate the area of the lateral bone window as shown by the ImageJ software interface. 1. dorsum sellae; 2. posterior clinoid process; 3. anterior clinoid process; 4. tuberculum sellae; 5. planum sphenoidale; 6. plasticine; 7. scope of the lateral bone window (LBW); software toolbar; 9. calculated result column; 10. Multi-angle scale Marker; L: left side; R: right side

Figure 2

Specimen showing the lateral bone window (LBW) (the scope within the yellow line). 1. dorsum sellae; 2. posterior clinoid process; 3. anterior clinoid process; 4. tuberculum sellae; 5. planum sphenoidale; 6. plasticine; 7. lateral bone window (LBW); 8. sellar floor; 9. carotid sulcus (CAS); 10. Multi-angle scale Marker (external: 1 cm; internal: 0.5 cm)

Figure 3

Lateral bone window (LBW) shape classifications in diagrammatic (left) and photographic (right) formats. According to the relative size of the APD, occurrence of STB, and occurrence of MCP or types of CCFH, LBW can be typed into four types as follows: I- open type: II- half-open type; III- complete type; IV- latch-like type; A: anterior clinoid process; P: posterior clinoid process; APD: distance between anterior clinoid and posterior processes; MTD: maximum transverse diameter of LBW; Q: quarter split point of MTD; M: mid-point of MTD; STB: sella turcica bridge; MLD: maximum longitudinal diameter of LBW; MCP; middle clinoid process; CCFH: carotico-clinoid foramen of Henle; LBW: lateral bone window of sella turcica

Figure 4

Diagram of the lateral bone height (LBH) (reflecting the height of the threshold of the bottom margin of the LBW). ACP; anterior clinoid process; LBH: lateral bone height of pituitary fossa; LBW: lateral bone window of sella turcica; MLD: maximum longitudinal diameter of LBW; CAS: carotid sulcus