Assessment of the Relation of the Optic Nerve to the Posterior Ethmoid and Sphenoid Sinuses by Computed Tomography

Abstract

Objective: The aim of this study was to observe the relationship of the sphenoid sinus and posterior ethmoid cells with the optic nerve.Material and Methods: 34 CT scans (68 sides) of paranasal sinuses of patients older than 18 years were retrospectively reviewed. Images were assessed in two planes -axial and coronal. We observed the position and relationship of the optic nerve to the posterior ethmoid and sphenoid sinuses, bony dehiscence and protrusion of the optic nerve into sinuses, and pneumatization of the anterior clinoid process.Results: The most frequent position of optic nerve (ON) was a location close to the posterior ethmoid and sphenoid sinuses without contacting or indentation of the wall -55.9 % (38 nerves). The bulging of ON to sphenoid sinus was found in 14.7 % (10 nerves) and the course of the nerve through sinus in 16 nerves (23.5 %). The position of ON intimately to both sinuses was observed in 5.9 % (4 nerves). Protrusion of ON, dehiscence of the bony wall and pneumatization of anterior clinoid process (ACP) was seen in 12 (35.3 %), 4 (11.8 %) and 9 (26.5 %) patients, respectively. Both the protrusion of ON and ACP pneumatization were present in 8 (23.5 %) patients on the right side and in 5 (14.7 %) patients on the left side.Conclusion: Variations of posterior ethmoid and sphenoid sinuses are numerous and may entail potential risk of injury of the ON during sinus surgery. Knowledge of individual differences and configurations in the operation area may help the surgeon to prevent complications. Computed tomography is the preferred radiographic modality for evaluation of bony variations and the pathology of this region.

Study of the relationship between sphenoid sinus volume and protrusions in the sphenoid sinus

“…If there are some protrusions in the SS or pneumatization of ACP, the volume of SS should be larger, which makes people easy to identify and visualize nearby structures of SS and adapt to surgery [17][18][19]. When you do ON decompression, you should take into account that there is an ICA protrusion except for ON protrusion in the SS because ICA protrusion usually accompanies with ON protrusion and pays attention to protect ICA and other structures during surgery.…”

Anatomical variation of the extracranial course of the optic nerve in the floor of the sphenoid sinus: first reported case

“…Variant courses have been previously reported, including cases in which the optic nerve bulged into the sinus or even traversed it. [3][4][5] However, we could find no previous report of the optic nerve occupying such a low position within the floor of the sinus. Figures 3 and 4 show further detail of this previously unreported anatomical variation.…”

Clinical Characteristics of Sphenoid Sinus Fungal Ball Patients With Visual Disturbance

“…In addition, an antifungal medication, treatment outcome, and the time interval between symptom occurrence and surgery were also reviewed in patients with visual disturbances. Characteristic CT findings were reviewed to identify intrasinus opacification, a defect and sclerosis of the sphenoid sinus bony wall, and other sinus lesions [6,7]. Magnetic resonance imaging (MRI) was performed preoperatively in patients with visual disturbances.…”