Multidetector Computed Tomography Assessment of Anatomical Variations and Critical Sinonasal Landmarks: A Prospective Cross-Sectional Study

Abstract

Background: Anatomical variations of the paranasal sinuses and osteomeatal complex are common findings on multidetector computed tomography (MDCT). Although these variations are not necessarily associated with sinonasal disease, they have significant implications during Functional Endoscopic Sinus Surgery (FESS). Accurate preoperative identification of these anatomical variants helps surgeons avoid potentially serious intraoperative complications involving the orbit, optic nerve, skull base, and anterior cranial fossa.

Objective

To evaluate the anatomical variations of the paranasal sinuses and osteomeatal complex using multidetector computed tomography with special emphasis on critical anatomical landmarks relevant to Functional Endoscopic Sinus Surgery.

Specific objectives were:

• To study the types of anatomical variations of the paranasal sinuses and osteomeatal complex.
• To evaluate the clinical importance of these anatomical variations on preoperative computed tomography.
• To assess variations involving the cribriform plate, lamina papyracea, Onodi cells, sphenoid sinus pneumatization, anterior ethmoidal artery, supraorbital pneumatization, and optic canal types that may increase intraoperative risk.
• To determine the frequency of these anatomical variations using 16-slice MDCT.

Materials and Methods

A prospective cross-sectional study was conducted in the Department of Radiodiagnosis, VMKV MCH Salem, Tamilnadu, India. A total of 109 adult patients referred for multidetector CT evaluation of the paranasal sinuses were included after satisfying the inclusion and exclusion criteria.

All patients underwent non-contrast MDCT of the paranasal sinuses using a Siemens Emotion 16-slice CT scanner. Axial acquisition with multiplanar coronal and sagittal reconstructions was performed. The following anatomical variations were evaluated:

• Keros classification of the cribriform plate
• Haller cells
• Uncinate process attachment
• Onodi cells
• Optic nerve canal types
• Sphenoid sinus pneumatization
• Anterior ethmoidal artery relationship
• Supraorbital pneumatization

Data were analyzed using Microsoft Excel.

Results

A total of 109 patients were evaluated.

Type II cribriform plate was the commonest anatomical variant and was observed in 88 (80.7%) patients, whereas Type I and Type III cribriform plates were seen in 13 (11.9%) and 8 (7.3%) patients respectively.

Haller cells were present in 12 (11.01%) patients.

The uncinate process most commonly attached to the lamina papyracea (98; 88.9%), followed by attachment to the skull base (11; 10.09%) and middle turbinate (1; 0.91%).

Onodi cells were identified in 45 (41%) patients.

Regarding optic nerve canal configuration, Type I was the commonest pattern on both sides.

Sellar pneumatization of the sphenoid sinus was observed in 90 (82.5%) patients, whereas 19 (17.4%) demonstrated presellar pneumatization.

The anterior ethmoidal artery abutted the fovea ethmoidalis in 89 (81.6%) patients and the lateral lamella in 20 (18.3%) patients.

Supraorbital pneumatization was identified in 79 (72.4%) patients.

Conclusion

Anatomical variations of the paranasal sinuses are common findings on multidetector CT. Although these variants do not necessarily predispose patients to sinonasal pathology, they represent important surgical landmarks because they increase the risk of intraoperative complications during Functional Endoscopic Sinus Surgery.

Routine preoperative MDCT evaluation provides an accurate surgical roadmap, enabling identification of critical anatomical variations and thereby reducing operative morbidity and improving surgical outcomes.