A computerized tomographic study of height of ethmoidal skull base
Background: During Endoscopic Sinus Surgeries (ESS), the most important anatomical structures that need preoperative visualisation and evaluation are the lateral lamella and ethmoidal skull base as many reports of complications due to injury of these structures exist. Ethmoidal Skull Base (ESB) extends from the superior attachment of lateral lamella of cribriform plate to the junction of the lamina papyracea. The aim is to study and evaluate ESB using coronal sinus CT images.
Methods: Sixty coronal sinus CT scan images at the level of visualization of anterior ethmoidal artery canal were taken for studying the ESB on both sides. A horizontal line bisecting the orbit was taken as the base line reference for inferior extent. The height of the ESB was measured and classified into high, moderate and low ESB by taking 7 mm as upper limit and 4 mm as lower limit. Mean height of ESB in the study group was computed and its difference among gender and sides were noted and statistically analysed.
Results: ESB varied between 3.7 mm to 15.4 mm with mean height of 10.05 mm. Low ESB was found only in females and there was no statistically significant side asymmetry of ESB height.Conclusions: Preoperative recognition of low ESB and alerting the surgeon of the potential for iatrogenic injury by measuring the height of ESB needs to become a standard practice in order to minimize the complications during ESS.
Ritter FN. The middle turbinate and its relationship to the ethmoidal labyrinth and the orbit. Laryngoscope. 1982;92:479-82.
Sargi ZB, Casiano RR. Surgical anatomy of the paranasal sinuses. In: Kountakis SE, Onerci TM, eds. Rhinological and Sleep Apnea Surgical Techniques. 18th ed. New York: Springer; 2007: 17-26.
Stankiewicz JA, Chow JM. The low skull base: an invitation to disaster. Am J Rhinol. 2004;18:35-40.
Cumberworth VL, Sudderick RM, Mackay IS. Major complications of functional endoscopic sinus surgery. Clin Otolaryngol. 1994;19:248-53.
Basak S, Karaman CZ, Akdilli A, Mutlu C, Odabasi O, Erpek G. Evaluation of some important anatomical variations and dangerous areas of the paranasal sinuses by CT for safer endonasal surgery. Rhinology. 1998;36:162-7.
Lebowitz RA, Terk A, Jacobs JB, Holliday RA. Asymmetry of the ethmoid roof: analysis using coronal computed tomography. Laryngoscope. 2001;111:2122-4.
Lee JC, Song YJ, Chung YS, Lee BJ, Jang YJ. Height and shape of the skull base as risk factors for skull base penetration during endoscopic sinus surgery. Ann Otol Rhinol Laryngol. 2007;116:199-205.
Ali A, Kurien M, Shyamkumar NK, Selvaraj. Anterior skull base: high risk areas in endoscopic sinus surgery in chronic rhinosinusitis: a computed tomographic analysis. Indian J Otolaryngol Head Neck Surg. 2005;57:5-8.
Nair S. Importance of ethmoidal roof in endoscopic sinus surgery. Sci Rep. 2012;1:251.
Stammberger HR, Kennedy DW. Paranasal sinuses: anatomic terminology and nomenclature. The anatomic terminology group. Ann Otol Rhinol Laryngol Suppl. 1995;167:7-16.
Solares CA, Lee WT, Batra PS, Citardi MJ. Lateral lamella of the cribriform plate: software-enabled computed tomographic analysis and its clinical relevance in skull base surgery. Arch Otolaryngol Head Neck Surg. 2008;134(3):285-9.
Keros P. On the practical value of differences in the level of the lamina cribrosa of the ethmoid. Z Laryngol Rhinol Otol. 1962;41:809-13.
Rudmik L, Smith TL. Evaluation of the ethmoid skull base height prior to endoscopic sinus surgery: a preoperative CT evaluation technique. Int Forum Allergy Rhinol. 2012;2(2):151-4.
Meyers RM, Valvassori G. Interpretation of anatomic variations of computed tomography scans of the sinuses: a surgeon’s perspective. Laryngoscope. 1998;108:422-5.
Justin Elfred, Lan B. Paber, Michael Salvador D. Cabato, Josefino G. Hernandez, Romeo L. Villarta Jr. Radiographic analysis of the ethmoid roof based on Keros classification among Filipinos. Philipp J Otolaryngol Head Neck Surg. 2008;23(1):15-9.
Soraia Ale Souza, Marcia Maria Ale de Souza, Marcos Idagawa, Ângela Maria Borri Wolosker, Sérgio Aron Ajzen. Computed tomography assessment of the ethmoid roof: a relevant region at risk in endoscopic sinus surgery. Radiol Bras. 2008;41(3):143-7.
Gauba V, Saleh GM. Radiological classification of anterior skull base anatomy prior to performing medial orbital wall decompression. Orbit. 2006;25:93-6.
Floreani SR, Nair SB, Switajewski MC, Wormald PJ. Endoscopic anterior ethmoidal artery ligation: a cadaver study. Laryngoscope. 2006;116(7):1263-7.
Nitinavakarn B, Thanaviratananich S, Sangsilp N. Anatomical variations of the lateral nasal wall and paranasal sinuses: a CT study for endoscopic sinus surgery (ESS) in Thai patients. J Med Assoc Thai. 2005;88:763-8.
Jang YJ, Park HM, Kim HG. The radiographic incidence of bony defects in the lateral lamella of the cribriform plate. Clin Otolaryngol Allied Sci. 1999;24:440-2.
Zacharek MA, Han JK, Allen R, Weissman JL, Hwang PH. Sagittal and coronal dimensions of the ethmoid roof: a radioanatomic study. Am J Rhinol. 2005;19(4):348-52.