title: The prevalence of spinal epidural lipomatosis on magnetic resonance imaging.
abstract: Spinal epidural lipomatosis (SEL) refers to an excessive accumulation of fat within the epidural space. It can be idiopathic or secondary, resulting in significant morbidity. The prevalence of SEL, including idiopathic and secondary SEL, and its respective risk factors are poorly defined.
  
  
  
  We sought to: (1) assess the prevalence of SEL among patients who underwent a dedicated magnetic resonance imaging (MRI) scan of the spine-including incidental SEL (ie, SEL without any spine-related symptoms), SEL with spine-related symptoms, and symptomatic SEL (ie, with symptoms specific for SEL); and (2) assess factors associated with overall SEL and subgroups. In addition, we assessed differences between SEL subgroups.
  
  
  
  We reviewed the records of 28,902 patients, aged 18 years and older with a spine MRI (2004 to 2015) at two tertiary care centers. We identified SEL cases by searching radiology reports for SEL, including synonyms and misspellings. Prevalence numbers were calculated as a percentage of the total number of patients. We used multivariate logistic regression analysis to identify factors associated with overall SEL and subgroups.
  
  
  
  The prevalence of overall SEL was 2.5% (731 of 28,902): incidental SEL, 0.6% (168 of 28,902); SEL with symptoms, 1.8% (526 of 28,902); and symptomatic SEL, 0.1% (37 of 28,902). Factors associated with overall SEL in multivariate analysis were the following: older age (odds ratio [OR]: 1.01, 95% confidence interval [CI]: 1.01-1.02, p<.001), higher modified Charlson comorbidity index (OR: 1.10, 95% CI: 1.07-1.13, p<.001), male sex (OR: 2.01, 95% CI: 1.71-2.37, p<.001), BMI>30 (OR: 2.59, 95% CI: 1.97-3.41, p<.001), Black/African American race (OR: 1.66, 95% CI: 1.24-2.23, p=.001), systemic corticosteroid use (OR: 2.59, 95% CI: 1.69-3.99, p<.001), and epidural corticosteroid injections (OR: 3.48, 95% CI: 2.82-4.30, p<.001).
  
  
  
  We found that about 1 in 40 patients undergoing a spine MRI had SEL; 23% of whom with no symptoms, 72% with spine-related symptoms, and 5% with symptoms specific for SEL. Our data help identify patients who might warrant an increased index of suspicion for SEL.
authors.affiliation: Department of Orthopaedic Surgery, Orthopaedic Spine Service, Massachusetts General Hospital-Harvard Medical School, 55 Fruit St, Boston, MA 02114, USA.
authors.forename: Nina C
authors.initials: NC
authors.lastname: Theyskens
authors.affiliation: Department of Orthopaedic Surgery, Orthopaedic Spine Service, Massachusetts General Hospital-Harvard Medical School, 55 Fruit St, Boston, MA 02114, USA. Electronic address: nunorui.pp@gmail.com.
authors.forename: Nuno Rui
authors.initials: NR
authors.lastname: Paulino Pereira
authors.affiliation: Department of Orthopaedic Surgery, Orthopaedic Spine Service, Massachusetts General Hospital-Harvard Medical School, 55 Fruit St, Boston, MA 02114, USA.
authors.forename: Stein J
authors.initials: SJ
authors.lastname: Janssen
authors.affiliation: Department of Orthopaedic Surgery, Orthopaedic Spine Service, Brigham and Women's Hospital-Harvard Medical School, 75 Francis St, Boston, MA 02115, USA.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Bono
authors.affiliation: Department of Orthopaedic Surgery, Orthopaedic Spine Service, Massachusetts General Hospital-Harvard Medical School, 55 Fruit St, Boston, MA 02114, USA.
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Schwab
authors.affiliation: Department of Orthopaedic Surgery, Orthopaedic Spine Service, Massachusetts General Hospital-Harvard Medical School, 55 Fruit St, Boston, MA 02114, USA.
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Cha
mesh_terms: D000328:Adult; D000368:Aged; D004824:Epidural Space / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D006801:Humans; D008068:Lipomatosis / Q000000981:diagnostic imaging / Q000453:epidemiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011871:Radiology; D013118:Spinal Cord Diseases / Q000000981:diagnostic imaging / Q000453:epidemiology*
keywords: Incidental spinal epidural lipomatosis; MRI; Prevalence; Risk factors; SEL; Spinal epidural lipomatosis; Symptomatic spinal epidural lipomatosis