Interpretation of Anatomic Variations of Computed Tomography Scans of the Sinuses: A Surgeon's Perspective

Abstract

Four hundred computed tomography (CT) scans of patients undergoing endoscopic sinus surgery were studied with particular attention to anatomic variations. Six specific variations were identified that may predispose the surgeon to inadvertent penetration of the orbit or anterior cranial cavity. These anatomic variants are: 1. lamina papyracea lies medial to the maxillary sinus ostium; 2. maxillary sinus hypoplasia; 3. fovea ethmoidalis abnormalities, such as low or sloping fovea and encephaloceles; 4. lamina papyracea dehiscence resulting in herniation of orbital content into the ethmoids; 5. sphenoid sinus wall variations such as septa attached to the carotid covering, and penetration of the sphenoid by the internal carotid artery or optic nerve; 6. sphenoethmoid cells (Onodi cells), the most posterior ethmoid cells pneumatizing lateral and superior to the sphenoid and intimately associated with the optic nerve.

Sphenoid sinus types, dimensions and relationship with surrounding structures

“…In conclusion, considering the common sphenoid sinus anatomical variations, a detailed preoperative radiological evaluation is needed to ascertain a successful transsphenoidal surgical procedure (Meyers et al, 1998). However, the standard clinical radiological techniques might not be able to visualize all elements that may increase the risk of iatrogenic injury.…”

Shaping the human face

“…Surgery requires awareness of the complexities of sinus anatomy and is made difficult by the high incidence of sinus anomalies. A recent study [4] indicated frequent variations on CT examination of 400 patients; 10% showed ethmoidal sinus hypoplasia, 4% maxillary sinus hypoplasia and incidences of 2-4% were noted for other gross anomalies. Another study [5] of 110 CT scans of patients suffering inflammatory sinus disease identified anomalies of the paranasal sinuses in 20% and further anomalies of the nasal septum and middle nasal concha in more than 55%.…”

A computerized tomographic study of height of ethmoidal skull base

“…13 Even though many studies reporting occurrence of low ESB causing complications during ESS exist [3][4][5][6][7][8][9] only limited studies have evaluated low ESB till date. 13,14 So the present study aims to evaluate and classify ESB preoperatively using coronal paranasal sinus CT scan images in Indian population and to deduce the relationship of ESB between side and gender. …”