Determination of the Most Suitable Cut-Off Point of the Cervical Foraminal Cross-Sectional Area at the C5/6 Level to Predict Cervical Foraminal Bony Stenosis.

Background: Cervical foraminal bony stenosis (CFBS) is a common degenerative spinal condition that causes radicular pain and functional impairment in the upper extremities. Accurate and objective diagnosis of CFBS remains challenging due to the absence of standardized morphometric criteria. This study aimed to determine an optimal cut-off value for the cervical foraminal cross-sectional area (CFCSA) at the C5/6 level as a diagnostic indicator of CFBS. Methods: We conducted a retrospective case-control study including 154 patients aged 50 years or older with clinically and radiologically confirmed CFBS and 150 age-matched asymptomatic controls. Cervical spine magnetic resonance imaging (MRI) was performed in all subjects and CFCSA measurements were obtained from sagittal T2-weighted images using a standardized protocol. Group differences were analyzed using t-tests and diagnostic performance was assessed using receiver operating characteristic (ROC) curve analysis. Results: The mean CFCSA was significantly lower in the CFBS group (25.65 ± 7.19 mm²) compared to the control group (43.00 ± 8.38 mm²; p < 0.001). ROC analysis identified a CFCSA threshold of 33.02 mm² as the optimal cut-off point for predicting CFBS, yielding a sensitivity of 86.4%, a specificity of 86.7%, and an area under the curve (AUC) of 0.94 (95% CI: 0.91-0.96). Conclusions: These findings suggest that CFCSA is a robust and reproducible morphological parameter for evaluating foraminal stenosis. The proposed cut-off may enhance diagnostic accuracy and aid in clinical decision-making for patients presenting with C6 radiculopathy. However, given this study's retrospective, single-center design, further validation through multicenter, prospective studies across multiple cervical levels is warranted.