Association of Spinal Epidural Lipomatosis With Systemic Lipid Metabolism in Patients With Lumbar Spinal Stenosis: A Propensity Score-Matched Study.

BACKGROUND CONTEXT: Spinal epidural lipomatosis (SEL) is often regarded as a local consequence of obesity, yet its relationship with systemic lipid metabolism and symptom severity in lumbar spinal stenosis remains unclear. Apolipoprotein B (ApoB) is central to atherogenic lipid transport and ectopic fat deposition. Examining the association between systemic lipid metabolic abnormalities, including elevated ApoB levels, and epidural fat accumulation may provide insights into the metabolic pathogenesis and clinical relevance of SEL.

PURPOSE: To determine whether SEL is associated with systemic lipid metabolic abnormalities and greater preoperative symptom burden in patients undergoing surgery for lumbar spinal stenosis (LSS).

PATIENT SAMPLE: A consecutive series of 1,145 patients who underwent posterior decompression for symptomatic LSS between December 2023 and December 2025. After 1:1 propensity score matching, 90 patients with SEL were compared with 90 patients without SEL.

OUTCOME MEASURES: Serum lipid and other biochemical markers, epidural fat/spinal canal (EF/SpC) index on lumbar magnetic resonance imaging, Oswestry Disability Index (ODI), and visual analog scale (VAS) scores for leg and back pain.

METHODS: SEL was diagnosed and graded on preoperative lumbar MRI according to the Borré classification, using the epidural fat/spinal canal index. Propensity score matching was performed for age, sex, body mass index (BMI), smoking history, drinking history, hypertension, and diabetes. Biochemical variables and preoperative clinical scores were compared between matched SEL and non-SEL patients. Conditional logistic regression was used to identify factors associated with SEL. BMI-adjusted partial Spearman correlation analyses were performed to evaluate associations between the EF/SpC index and biochemical markers. Regression-based trend analyses were conducted to assess changes in lipid-related markers across increasing SEL severity grades.

RESULTS: Among 1,145 patients with LSS, 105 (9.2%) met the diagnostic criteria for SEL. After matching, 90 patients with SEL were compared with 90 non-SEL controls. The SEL group had higher apolipoprotein B (ApoB) levels than controls, as well as higher low-density lipoprotein cholesterol, triglycerides, and total cholesterol. ApoB remained independently associated with SEL in conditional logistic regression (odds ratio per 0.1 g/L, 1.141; 95% confidence interval, 1.019-1.277; P=0.022). Within the SEL group, the EF/SpC index correlated positively with triglycerides (ρ=0.43, q<0.001) and ApoB (ρ=0.40, q=0.002), while atherogenic lipid markers increased progressively with SEL severity. Patients with SEL also showed higher Oswestry Disability Index and leg-pain visual analog scale scores, whereas back-pain scores were similar between groups.

CONCLUSION: In patients undergoing surgery for LSS, SEL was associated with a more atherogenic lipid profile after matching for BMI and other major baseline characteristics, as well as greater preoperative disability and leg pain. The association of ApoB with SEL, together with the graded relationships of ApoB and triglycerides with epidural fat burden, suggests that SEL may reflect systemic lipid metabolic dysfunction rather than local epidural fat deposition alone.

STUDY DESIGN: Retrospective, propensity score-matched cohort study.