Evaluation of postoperative nerve root oedema and analysis of risk factors in unilateral biportal endoscopic discectomy using the DESS sequence: preliminary results.

OBJECTIVE: This study aims to explore the application of the double-echo steady-state (DESS) sequence for the precise diagnosis of nerve root oedema in unilateral biportal endoscopic discectomy (UBED). This article explores the relationship between nerve root oedema and clinical symptoms, additionally investigating potential contributing risk factors. METHODS: Postoperative clinical efficacy was evaluated using visual analogue scale (VAS) scores and the Oswestry Disability Index (ODI). DESS cross-sectional images were evaluated with ImageJ software. The oedema coefficient derived from DESS served as the principal quantitative metric. We adopted Lasso regression for feature selection. Subsequently, a multifactorial analysis was performed with the selected factors using the forward selection method. RESULTS: Forty-nine patients (27 males and 22 females) were included in the study. The average oedema coefficient was 1.25 ± 0.43. The postoperative lower limb VAS score was significantly correlated with the swelling coefficient (p = 0.000). However, there was no correlation between the postoperative ODI and the swelling coefficient (p = 0.106). The features selected for inclusion in the model were "Age," "BMI," "Type of protrusion," "Disc height," "Width of spinal canal," "Lumbar curvature," and "Course of disease. "Multiple stepwise regression analysis confirmed that disc height (r = 0.092, p = 0.008) was significantly positively correlated with the degree of oedema, and disease course (r=-0.010, p = 0.020) was significantly negatively correlated with the degree of oedema. CONCLUSION: The DESS sequence can indicate changes in the corresponding compressed nerve and correlates strongly with the postoperative leg VAS score. Disease progression and disc height may be significant factors influencing postoperative nerve root oedema.