Determination of the Correlation Between the Extent of Sphenoid Sinus Pneumatization and the Variations of Adjacent Neurovascular Structures by Cone-Beam Computed Tomography: A Retrospective Study

The sphenoid sinus (SS) is intensely situated in the neurocranium of the skull and it is the most inaccessible sinus when compared to other sinuses. The degree of SS pneumatization is extremely variable and may endanger adjacent neurovascular structures, including the optic (ON), vidian (VN), maxillary (MN), and abducent nerves, the cavernous sinuses, and the internal carotid arteries. The SS constitutes an appropriate pathway to access lesions on the base of the skull. The study aimed to determine the pattern of pneumatization of the SS and its extensions, and to identify the correlation between the extent of pneumatization and neurovascular variations (protrusion/dehiscence). Cone-beam computed tomography (CBCT) scan records were retrieved from the outpatient database of the department of oral medicine and radiology, archived in the Digital Imaging and Communications in Medicine folder. CBCT scans of 100 patients were selected for the study based on the inclusion and exclusion criteria. These scans were analyzed using Carestream 3-D viewer software version 3.10.10. All CBCT scans were independently evaluated by two experienced oral and maxillofacial radiologists, and disagreements were resolved by consensus review. Interobserver agreement for identifying neurovascular protrusion and dehiscence showed good reliability using Cohen's kappa statistics (κ = 0.82). The collected data were analyzed using SPSS Statistics software version 21 (IBM, Armonk, New York, United States). Descriptive statistics and Pearson's correlation coefficient were used for prevalence and correlation analysis, with p < 0.05 considered statistically significant. Although the total sample size was adequate (n = 100), smaller subgroups such as sellar pneumatization and dorsal clival extension were interpreted cautiously due to limited sample representation. In the present study, the pattern of pneumatization is as follows: presellar 21%, sellar 12%, and postsellar 67%. The postsellar type of pneumatization is apparent in a higher percentage for both genders of selected age groups. The prevalence of clival extensions is as follows: 24% subdorsal, 5% dorsal, 38% occipital, and 33% combined). The occipital type of clival extension was apparent in a higher percentage. In 62% of the subjects, lateral extension was present, and the bilateral type of extension was the most prevalent one. The distribution of lateral extension varies markedly with respect to age and gender. The percentage of protrusion of internal carotid artery (ICA), MN, ON, and VN are as follows 40, 59, 45, and 61%, and the percentage of dehiscence of ICA, MN, ON, and VN are 8, 17, 4, and 16%, respectively. ON protrusion showed a positive correlation when anterior clinoid extension was present unilaterally on the right (p < 0.05) and left side (p < 0.05), but when anterior clinoid extension occurred bilaterally, there was no ON protrusion, and it was statistically insignificant (p > 0.05). ON dehiscence was correlated with right clinoid extension and was found to be statistically significant with p < 0.05. VN protrusion showed a positive correlation when lateral extension was present unilaterally on the right (p < 0.05) and left side (p < 0.05), but when lateral extension occurred bilaterally, there was no VN protrusion, and it was found to be statistically insignificant (p > 0.05). VN dehiscence demonstrated a positive correlation when lateral extension was present on the right side (p < 0.05), but when lateral extension occurred on the left and bilateral sides, there was no VN dehiscence, and it was statistically insignificant (p > 0.05). MN protrusion demonstrated a positive correlation when lateral extension was present unilaterally on the right (p < 0.05) and left side (p < 0.05), but when lateral extension occurred bilaterally, there was no MN protrusion that was statistically insignificant (p > 0.05). MN dehiscence was positively correlated when lateral extension was present on the right side (p > 0.05), but when lateral extension occurred on the left and bilateral sides, there was no MN dehiscence, and it was statistically insignificant (p > 0.05). Preoperative CBCT evaluation can therefore assist surgeons in identifying high-risk anatomical variants, minimizing inadvertent neurovascular injury, and improving surgical planning during minimally invasive skull base and SS procedures.