Negative impact of spinal epidural lipomatosis on the surgical outcome of posterior lumbar spinous-splitting decompression surgery: a multicenter retrospective study

Abstract Background Context Spinal epidural lipomatosis(SEL) results from excess lumbarepidural fat (EF) accumulation that compresses the cauda equinaor nerve roots. Guidelines for the therapeutic management of SEL are not currently available. Purpose To elucidate the efficacy of lumbar decompressionsurgery in SEL. Study Design Multicenter retrospective study. Patient Sample A total of 288 consecutive patients who underwent posterior lumbarspinous-splitting decompressionsurgery for lumbar spinal canal stenosis(LSS) and followed up greater than 2 years at participating institutions were retrospectively reviewed. Outcome Measures Japanese Orthopedic Association Back Pain Evaluation Questionnaire (JOABPEQ) and Roland-Morris Disability Questionnaire (RDQ). Methods Participants were divided into two groups according to the ratio of EF to anteroposterior diameter of the spinal canal(EF/SC-L) at the spinal level with maximum dural tube compression. Patients with EF/SC-L of ≥0.6 and Results Analysis using the RDQ and JOABPEQ showed that the 1- and 2-year postoperative scores were significantly better than the preoperative scores in the both groups. Multivariable Poisson regression analysis demonstrated that SEL was significantly associated with “not effective” for decompressionsurgery in the 1-year postoperative outcomes of walking ability ([RR] 1.5, 95% confidence interval [CI] 1.0–2.2) and social life (RR 1.3, 95%CI 1.0–1.8) and the 2-year postoperative outcomes of walking ability (RR 1.6, 95%CI 1.2–2.3). Matching analysis showed that SEL was significantly associated with “not effective” with lumbar decompressionsurgery in the 2-year postoperative outcomes of walking ability (p = 0.02). Conclusions Patients with SEL exhibited significant improvements in surgical outcomes at 1- and 2-years postoperatively. However, compared with the non-SEL group, the efficacy of posterior lumbarspinous-splitting decompressionsurgery was worse in the SEL group, especially for walking ability. These results indicate that EF accumulation should be considered when planning treatment for patients with LSS and estimating the efficacy of lumbar decompressionsurgery.