Fig. 1

Gray matter volume (GMV) across groups. Group-stratified distributions are shown for mean C5-C7 (A) ventral and (B) dorsal horn grey matter volume. Tukey pairwise comparisons indicate statistically significant differences (p < 0.05) between groups at a univariate level for the CON vs. FMO group comparison. FMO individuals with fibromyalgia taking opioids; FMN individuals with fibromyalgia not taking opioids, CON controls.