Tumor occupancy ratio as a predictor of neurological recovery after hemilaminectomy for intradural spinal tumors.

BACKGROUND: Hemilaminectomy is increasingly used as a less invasive alternative to conventional laminectomy for resection of intradural spinal tumors. This study aimed to evaluate whether the tumor occupancy ratio on preoperative axial magnetic resonance imaging (MRI) was associated with postoperative neurological improvement after hemilaminectomy for selected intradural spinal tumors and to describe the surgical outcomes of this approach. METHODS: We retrospectively reviewed adult patients who underwent hemilaminectomy for intradural spinal tumors between 2018 and 2024 at a single institution and had at least 6 months of follow-up. Neurological status was assessed preoperatively and at the last follow-up using the modified McCormick scale (MMS). Clinical, radiographic, and operative variables, including tumor occupancy ratio on axial MRI, were analyzed using univariate tests and multivariable logistic regression. RESULTS: Forty-six patients were included (mean age 56.3±14.0 years; 78% female). Gross total resection was achieved in 44 of 46 patients (96%). The mean hemilaminectomy corridor ratio, measured as the hemilaminectomy width divided by the interpedicular distance, was 0.55±0.12. At the last follow-up (median 27 months), 37 patients (80.4%) showed neurological improvement. Two patients (4.3%) developed postoperative neurological deterioration. On univariate analysis, sagittal tumor extent, operative time, blood loss, and tumor occupancy ratio were associated with MMS improvement. On multivariable analysis, tumor occupancy ratio was the only variable independently associated with postoperative neurological non-improvement [odds ratio (OR) 1.31, 95% confidence interval (CI): 1.02-1.68; P=0.03]. CONCLUSIONS: Hemilaminectomy achieved a high rate of gross total resection with favorable neurological outcomes in selected patients with solid intradural spinal tumors. Tumor occupancy ratio was associated with postoperative neurological outcome and may be useful as a preoperative prognostic imaging marker, although further validation is required.