TAC1 and Low back pain: Furthermore, clinical studies have reported a correlation between positive substance P test results in cases of IVD degeneration and the degree of LBP observed during contrast‐enhanced IVD imaging.6 IVD tissues in patients with LBP also contain an abundance of proinflammatory mediators compared to patients with lower limb pain alone, and these are reportedly expressed in even greater abundance in cases of IVD degeneration.7 It is therefore believed that inflammatory cytokines act on the nerve endings around the IVD to cause LBP.