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  • Morphometric Analysis of the Middle Clinoid Process Using Maxillofacial CT Scans.

    Final Number:

    Christopher Miller MD; Roukoz B. Chamoun MD

    Study Design:
    Clinical Trial

    Subject Category:

    Meeting: Congress of Neurological Surgeons 2015 Annual Meeting

    Introduction: The interest in detailed anatomy of the sellar and parasellar region has resurged recently due to the wide clinical applications of the expanded endoscopic approaches to the skull base. The middle clinoid process (MCP) is a bony structure that can affect wide endoscopic exposure of the sellar and parasellar region. The purpose of this project is to study and analyze the anatomical variations of the MCP in the general population using CT scans.

    Methods: 150 maxillofacial CT scans were reviewed to characterize the MCP. Only adult patients with no pathology in sellar region that could potentially cause changes in the morphology of the MCP. Measurements were made in the axial and sagittal planes to determine maximum length, diameter, distances from key structures and angulation of the MCP.

    Results: The prevalence of the MCP was 30.67% in males and 42.7% in females. Of subjects found to have an MCP, 41.82% were ring forming while 76.36% were pneumatized. Quantitatively the average base diameter was 4.6±1.4mm in the axial plane and 5.0±1.8mm in the sagittal plane, average maximum length was 4.7±1.7mm, average distance from midline was 5.9±2.3mm, average distance from the clival sellar angle was 10.5±3.4mm, average angle in the sagittal plane was 88.5±21.1º, and average angle in the axial plane was 45.2±15.5º. There were no significant differences in gender, age, ethnicity, race, or laterality.

    Conclusions: A clear understanding of the sellar and parasellar anatomy is crucial for performing successful and safe expanded endoscopic approaches to treat skull base pathologies. This study provides a quantitative anatomical characterization of the MCP in the general population. Surgeons should obviously carefully review the CT scan of every patient to detect unusual variations and pathological involvement of the skull base.

    Patient Care: This research provides surgeons with an improved understanding of the anatomy of the sella tursica, specifically the middle clinoid process. This better understanding will assist surgeons in providing safe and effective surgical intervention to patients with sella tursica pathology.

    Learning Objectives: By conclusion if this session, participants should be able to: 1) Identify the middle clinoid process on CT scans, 2) Understand the basic morphology and variants of the middle clinoid process, 3) Understand how the presence and morphology of the middle clinoid process can impact the transphenoidal surgical approach.

    References: 1. Peris-Celda M, Kucukyuruk B, Monroy-Sosa A, Funaki T, Valentine R, Rhoton AL Jr. The recesses of the sellar wall of the sphenoid sinus and their intracranial relationships. Neurosurgery. 2013 Dec;73(2 Suppl Operative):117-31; 2. Spektor S, Dotan S, Mizrahi CJ. Safety of drilling for clinoidectomy and optic canal unroofing in anterior skull base surgery. Acta Neurochir (Wien). 2013 Jun;155(6):1017-24. 3. Inoue T, Rhoton AL Jr, Theele D, Barry ME. Surgical approaches to the cavernous sinus:a microsurgical study. Neurosurgery. 1990 Jun;26(6):903-32. 4. Wang J, Wang R, Lu Y, Yao Y, Qi S. Anatomical analysis on the lateral bone window of the sella turcica: a study on 530 adult dry skull base specimens. Int J Med Sci. 2014 Jan 3;11(2):134-41. doi: 10.7150/ijms.7137. eCollection 2014. 5. Cheng Y, Wang C, Yang F, Duan Y, Zhang S, Wang J. Anterior clinoid process and the surrounding structures. J Craniofac Surg. 2013 Nov;24(6):2098-102. 6. Dagtekin A, Avci E, Uzmansel D, Kurtoglu Z, Kara E, Uluc K, Akture E, Baskaya MK. Microsurgical anatomy and variations of the anterior clinoid process. Turk Neurosurg. 2014;24(4):484-93. 7. Gupta N, Ray B, Ghosh S. A study on anterior clinoid process and optic strut with emphasis on variations of caroticoclinoid foramen. Nepal Med Coll J. 2005;7(2):141-144. 23. 8. Erturk M, Kayalioglu G, Govsa F. Anatomy of the clinoidal region with special emphasis on the caroticoclinoid foramen and interclinoid osseous bridge in a recent Turkish population. Neurosurg Rev. 2004;27(1):22-26.

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