Correlation of spinal epidural fat volume with body mass index: a longitudinal study.

Purpose: Spinal epidural lipomatosis is abnormal accumulation of normal fat in the epidural space with weight loss suggested as first-line therapy in select symptomatic patients. However, moderate to large longitudinal studies establishing concordant changes between body mass index and epidural fat are lacking. The purpose of this study was to longitudinally assess this relationship.

Methods: We performed an ancillary study of the Habitual Diet and Avocado Trial. Baseline and six-month abdominal MRIs were analyzed for 98 overweight or obese but otherwise healthy subjects. Dorsal epidural fat volumes in the lumbar spine were measured and correlated with changes in body mass index, changes in visceral fat volume, and demographic information.

Results: There was a linear relationship between body mass index changes and epidural fat volume changes with a one-point change in body mass index corresponding to a 45 mm change in dorsal epidural fat volume (p < 0.001, 95% CI 31.87 to 76.77) as well as between visceral fat volume changes and epidural fat volume changes (regression coefficient 0.51, p < 0.001, 95% CI 0.22 to 0.47). Age was inversely related with subjects older than 45.7 years tending to lose epidural fat (regression coefficient -0.22, p = 0.025, 95% CI -10.43 to -0.72).

Conclusion: Changes in spinal dorsal epidural fat volume parallel changes in body mass index and visceral fat, supporting weight loss as initial treatment for uncomplicated obesity-associated spinal epidural lipomatosis.