Lumbosacral Epidural Lipomatosis: A Retrospective Matched Case-Control Database Study Baris Yildirim 1 , Varun Puvanesarajah 2 , Howard S. An 3 , Wendy M. Novicoff 1 , Amit Jain 2 , Francis H. Shen 1 , Hamid Hassanzadeh 1 - OBJECTIVE: We present the largest known consecutive series of patients with epidural lipomatosis (EL) to char- acterize demographics and clinical symptoms of patients with EL on magnetic resonance imaging (MRI), and compare these characteristics against a matched control group. - METHODS: Patients evaluated for pathology requiring lumbar MRI imaging between September 2010 and September 2015 were retrospectively reviewed and included in this study if they were diagnosed with EL on a radiologic note during any visit to our medical center. One hundred ninety-nine patients fulfilled the study criteria and were included in the study cohort. A separate patient cohort of 199 unique, age- and gender-matched controls without lumbosacral EL was generated from a database of patients with lumbar MRI imaging during the same period. - RESULTS: Average age at diagnosis was 54.9 years (range, 25e84 years). One hundred thirty-three patients (66.8%) were men. On univariate analysis, patients with EL were more likely to have history of smoking (odds ratio [OR] 1.90, 95% confidence interval [CI] 1.23e2.94, P [ 0.004), diabetes mellitus type 2 (OR 2.17, 95% CI 1.33e 3.56, P [ 0.002), or be on disability (OR 4.43, 95% CI 2.48e7.91, P < 0.001). Furthermore, patients with EL had significantly increased median body mass index compared with controls (36.7 vs. 29.4 kg/m 2 ; P < 0.001). - CONCLUSIONS: Patients with lumbosacral EL tend to be obese with a high incidence of type 2 diabetes mellitus, suggesting that this pathology may be a sequela of meta- bolic syndrome. Future research topics should include the pathogenesis of EL, as well as treatment outcomes of surgical versus primary care management. INTRODUCTION F irst described in 1975, 1 epidural lipomatosis (EL) is hypertrophy of the adipose tissue in the epidural space often diagnosed on magnetic resonance imaging (MRI). This diagnosis must be differentiated from other pathologies, such as spinal angiolipoma, abscess, and other primary and secondary spinal tumors, that can appear similarly on routine imaging. 2 Epidural fat deposition can on rare occasions result in pain or neurological deficits due to compression of nerve roots and/or the spinal cord. Back pain and lower extremity weakness are the most common presenting symptoms, and other reported symptoms include numbness, paresthesias, radicular pain, and bowel or bladder incontinence. 3-6 Causes of EL vary, although major causes all result in pathologic increases in spinal adipose tissue synthesis and deposition. Pre- vious literature has suggested that 55.3% of cases with EL are attributable to exogenous steroid use and resulting adipose tissue hypertrophy. Endogenous steroid overproduction has also been implicated. Although obesity is also reported in several case Key words - Epidural fat - Epidural lipomatosis - Lumbar spine - Lumbosacral spine - Metabolic syndrome - Obesity Abbreviations and Acronyms BMI: Body mass index CI: Confidence interval EL: Epidural lipomatosis MRI: Magnetic resonance imaging OR: Odds ratio From the 1 Department of Orthopaedic Surgery, University of Virginia, Charlottesville, Virginia; 2 Department of Orthopaedic Surgery, Johns Hopkins University, Baltimore, Maryland; and 3 Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, Illinois, USA To whom correspondence should be addressed: Hamid Hassanzadeh, M.D. [E-mail: hh4xd@hscmail.mcc.virginia.edu] Citation: World Neurosurg. (2016) 96:209-214. http://dx.doi.org/10.1016/j.wneu.2016.08.125 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com 1878-8750/$ - see front matter ª 2016 Elsevier Inc. All rights reserved. WORLD NEUROSURGERY 96: 209-214, DECEMBER 2016 www.WORLDNEUROSURGERY.org 209 Original Article