Clinical significance of early magnetic resonance imaging assessment following separation surgery for metastatic spinal cord compression.

BACKGROUND CONTEXT: Separation surgery has emerged as a key surgical strategy for metastatic spinal cord compression (MSCC), aiming to create a circumferential decompressive margin that allows safe delivery of postoperative radiotherapy. However, despite its widespread adoption, the clinical value of objectively confirming separation on early postoperative magnetic resonance imaging (MRI) remains unclear.

PURPOSE: To evaluate whether separation success confirmed by MRI at 2-3 weeks postoperatively is associated with improved neurological recovery, functional outcomes, and survival in patients with MSCC.

STUDY

DESIGN

Retrospective cohort study.

PATIENT SAMPLE: A total of 59 patients who underwent posterior separation surgery for MSCC between 2020 and 2023 were included. All patients underwent metal artifact-reduced MRI at 3 weeks postoperatively and were classified into a separation group (Group S; n=26, 44.1%) or a nonseparation group (Group NS; n=33, 55.9%) based on MRI findings.

OUTCOME MEASURES: Primary outcomes included neurological recovery (motor grade and ambulation status), overall survival, and length of hospital stay. Secondary outcomes included radiologic parameters (Bilsky grade and Spinal Instability Neoplastic Score), postoperative complications, and radiotherapy administration. Successful separation was defined as a cerebrospinal fluid margin ≥2 mm between the tumor and spinal cord.

METHODS

Baseline characteristics were compared using appropriate parametric and nonparametric tests. Logistic regression was used to identify predictors of separation success. Survival outcomes were analyzed using the Kaplan-Meier method with log-rank testing and Cox proportional hazards regression.

RESULTS

Baseline characteristics were comparable between groups except for Bilsky grade distribution. Group NS had a significantly higher proportion of Bilsky Grade 3 lesions (28/33 vs 16/26, p=.041). Compared with Group NS, Group S demonstrated significantly higher postoperative motor grades (4.54 vs 3.67, p=.015), higher ambulation rates (92.3% vs 69.7%, p=.032), and shorter hospital stays (15.81 vs 23.94 days, p=.042). Overall survival was significantly longer in Group S (13.31 vs 6.02 months, p=.001). Logistic regression identified preoperative Bilsky grade as the only independent predictor of separation failure (OR=0.248, 95% CI: 0.069-0.888, p=.032). Cox regression demonstrated that separation failure was associated with a 2.63-fold increased risk of mortality (p=.006).

CONCLUSIONS

Separation success confirmed on early postoperative MRI obtained 2-3 weeks after surgery was associated with early neurological recovery, higher postoperative ambulation rates, and prolonged survival in patients with MSCC. Despite technical limitations, early postoperative MRI provides a practical and objective means of assessing decompression adequacy and may support postoperative evaluation and treatment planning following separation surgery for MSCC.