A morphometric and typological study of the clivus for guiding endoscopic skull base surgery

Abstract

Objectives: Endoscopic transnasal transsphenoidal approaches to lesions involving the clivus carry several disadvantages for midline skull base lesions, including higher morbidity and a lesser extent of resection. This study aimed to investigate the anatomical detail of the clivus in order to identify failure criteria and improve success parameters. Methods: Clivus length, width, thickness and area, opisthion–dorsum sellae length, dorsum sellae–basion angle, and foramen magnum length and width were evaluated on 32 adult dry human skulls using ImageJ. The prevalence of clivus shape, border type and surface type was also determined. Results: Mean clivus length was 3.52±0.37 cm in females and 3.25±0.63 cm in males, and clivus width was 1.42±0.50 cm and 1.41±0.57 cm, respectively. Among clivus types, the long-straight type had the greatest length (4.16±0.25 cm) and the short-sloped type the shortest (2.98±0.36 cm). The most common clivus shape was the short-sloped type (56.25%), the most frequent border type was inward-curved (40.6%), and the most common surface type was concave (56.25%). An asymmetric shape was observed in 31.25% of specimens, an irregular surface in 25%, and asymmetric borders in 31.3%. Foramen magnum length was significantly greater in males (p<0.001). Conclusion: The long-straight clivus appears most suitable for transnasal/transclival access and tumour resection, whereas asymmetric types require careful preoperative evaluation. The symmetric border type showed a regular and balanced morphology, providing a consistent bony boundary that may aid intraoperative orientation.

Keywords

• anatomy
• clivus
• foramen magnum
• skull base
• sphenoid bone

Ethical Statement

This study was approved by the Ethical Committee of Izmir Bakircay University Research Department, where the research was conducted, and adhered to the principles of the Declaration of Helsinki (Decision No: 1642, Research ID: 1622, Date: 03.07.2024).

References

1. Campos D, Jotz GP, Goulart GH, Malysz T. The clival canal. Arq Neuropsiquiatr 2015;73:1047.
2. Di Chiro G, Anderson WB. The clivus. Clin Radiol 1965;16:211–23.
3. Murjani B, Bhosale R, Ramaswami E, Kadam S, Ramchandani A. Anatomical variations of clivus: a descriptive anatomical study. Surg Radiol Anat 2021;43:945–51.
4. Rai R, Iwanaga J, Shokouhi G, Loukas M, Mortazavi MM, Oskouian RJ, Tubbs RS. A comprehensive review of the clivus: anatomy, embryology, variants, pathology, and surgical approaches. Childs Nerv Syst 2018;34:1451–8.
5. Vutskits L, Reisch R, Patonay L, Fries G. The rete mirabile of the clivus and the dorsum sellae. A microanatomical study. Minim Invasive Neurosurg 1996;39:138–40.
6. Jinkins JR. Atlas of neuroradiologic embryology, anatomy, and variants. Philadelphia (PA): Lippincott Williams & Wilkins; 2000. p. 63–5.
7. Zorlu F, Gurkaynak M, Yildez F, Oge K, Lale Atahan I. Conventional external radiotherapy in the management of clivus chordomas with overt residual disease. Neurol Sci 2000;21:203–7.
8. Bailey CS, Fisher CG, Boyd MC, Dvorak MF. En bloc marginal excision of a multilevel cervical chordoma. Case report. J Neurosurg Spine 2006;4:409–14.

9. Cheng Y, Zhang S, Chen Y, Zhao G. Safe corridor to access clivus for endoscopic trans-sphenoidal surgery: a radiological and anatomical study. PLoS One 2015;10:e0137962.
10. Fernandez-Miranda JC, Gardner PA, Snyderman CH, Devaney KO, Mendenhall WM, Suárez C, Rinaldo A, Ferlito A. Clival chordomas: a pathological, surgical, and radiotherapeutic review. Head Neck 2014;36:892–906.
11. Rao D, Stein R, Jenson M, Patel J, Fiester P. Imaging review of the endoscopic operative corridor for clivus lesions. Curr Probl Diagn Radiol 2023;52:66–76.
12. Sheikh S, Iwanaga J, Rostad S, Rustagi T, Oskouian RJ, Tubbs RS. The first histological analysis of the tissues lining the fossa navicularis: insights to its etiology. Cureus 2017;9:e1299.
13. Rhines LD, Fourney DR, Siadati A, Suk I, Gokaslan ZL. En bloc resection of multilevel cervical chordoma with C-2 involvement. Case report and description of operative technique. J Neurosurg Spine 2005;2:199–205.
14. Sajisevi M, Hoang JK, Eapen R, Jang DW. Nasopharyngeal masses arising from embryologic remnants of the clivus: a case series. J Neurol Surg Rep 2015;76:e253–7.
15. Sekhar LN, Jannetta PJ, Burkhart LE, Janosky JE. Meningiomas involving the clivus: a six-year experience with 41 patients. Neurosurgery 1990;27:764–81.
16. Jozsa F, Das JM. Metastatic lesions of the clivus: a systematic review. World Neurosurg 2022;158:190–204.
17. Di Ieva A, Bruner E, Haider T, Rodella LF, Lee JM, Cusimano MD, Tschabitscher M. Skull base embryology: a multidisciplinary review. Childs Nerv Syst 2014;30:991–1000.
18. Prescher A. The craniocervical junction in man, the osseous variations, their significance and differential diagnosis. Ann Anat 1997;179:1–19.
19. Yurasakpong L, Suwannakhan A, Asuvapongpatana S, Tubbs RS, Iwanaga J, Iamsaard S, Samrid R, Berkban T, Chaiyamoon A. Anatomical and morphometric study of variations of the clivus in dried human skulls from the Northeastern Thai population. Surg Radiol Anat 2025;47:214.
20. Atalar M, Ozum U. Monostotic fibrous dysplasia of the clivus: imaging findings. Turk Neurosurg 2010;20:77–81.
21. DiCaprio MR, Enneking WF. Fibrous dysplasia: pathophysiology, evaluation, and treatment. J Bone Joint Surg Am 2005;87:1848–64.
22. Hoffmann E, Prescher A. The clivus: anatomy, normal variants and imaging pathology. Clin Neuroradiol 2011;22:123–9.
23. Ji W, Wang XY, Xu HZ, Yang XD, Chi YL, Yang JS, Yan SF, Zheng JW, Chen ZX. The anatomic study of clival screw fixation for the craniovertebral region. Eur Spine J 2012;21:1483–91.
24. Jiang WH, Zhao SP, Xie ZH, Zhang H, Zhang J, Xiao JY. Endoscopic resection of chordomas in different clival regions. Acta Otolaryngol 2009;129:71–83.
25. Lustig LR, Holliday MJ, McCarthy EF, Nager GT. Fibrous dysplasia involving the skull base and temporal bone. Arch Otolaryngol Head Neck Surg 2001;127:1239–47.
26. Melsen B. Time and mode of closure of the spheno-occipital synchondrosis determined on human autopsy material. Acta Anat (Basel) 1972;83:112–8.
27. Schick B, Prescher A, Hofmann E, Steigerwald C, Draf W. Two occult skull base malformations causing recurrent meningitis in a child: a case report. Eur Arch Otorhinolaryngol 2003;260:518–21.
28. Samii M, Knosp E. Transoral approach. In: Approaches to the clivus: approaches to no man’s land. Heidelberg: Springer-Verlag; 1992.
29. Fisahn C, Schmidt C, Rostad S, Li R, Rustagi T, Alonso F, Shoja MM, Iwanaga J, Chapman JR, Oskouian RJ, Tubbs RS. Adult ligament of the dens lacks notochordal tissue: application to better understanding the origins of skull base chordomas. World Neurosurg 2017;101:42–6.
30. Jacquemin C, Bosley TM, Al Saleh M, Mullaney P. Canalis basilaris medianus: MRI. Neuroradiology 2000;42:121–3.
31. Koksel T, Crockard A. Clivus through the eyes of the transoral surgeon. Turkish Neurosurgery 1990;1:146–50.
32. Fournier HD, Mercier P, Roche PH. Surgical anatomy of the petrous apex and petroclival region. Adv Tech Stand Neurosurg 2007;32:91–146.
33. Kapoor V, Johnson DR, Fukui MB, Rothfus WE, Jho HD. Neuroradiologic-pathologic correlation in a neurenteric cyst of the clivus. AJNR Am J Neuroradiol 2002;23:476–9.
34. Kawase T, Shiobara R, Ohira R, Toya S. Developmental patterns and characteristic symptoms of petroclival meningiomas. Neurol Med Chir (Tokyo) 1996;36:1–6.
35. Shoja MM, Ramdhan R, Jensen CJ, Chern JJ, Oakes WJ, Tubbs RS. Embryology of the craniocervical junction and posterior fossa, part I: development of the upper vertebrae and skull. Clin Anat 2018;31:466–87.
36. Ramesh T, Nagula SV, Tardieu GG, Saker E, Shoja MM, Loukas M, Oskouian RJ, Tubbs RS. Update on the notochord including its embryology, molecular development, and pathology: a primer for the clinician. Cureus 2017;9:e1137.
37. Shoja MM, Johal J, Oakes WJ, Tubbs RS. Embryology and pathophysiology of the Chiari I and II malformations: a comprehensive review. Clin Anat 2018;31:202–15.
38. Tubbs RS, Hansasuta A, Loukas M, Louis RG Jr, Shoja MM, Salter EG, Oakes WJ. The basilar venous plexus. Clin Anat 2007; 20:755–9.
39. Tubbs RS, Griessenauer CJ, Loukas M, Zurada A, Shoja MM, Cohen-Gadol AA. The enigmatic clival canal: anatomy and clinical significance. Childs Nerv Syst 2010;26:1207–10.