A multicenter randomized controlled trial on the efficacy of intradiscal methylene blue injection for chronic discogenic low back pain: the IMBI study

A study published in PAIN in 2010 showed remarkable effects of intradiscal methylene blue (MB) injections compared with placebo on pain intensity in patients with chronic discogenic low back pain (CD-LBP). Both groups received lidocaine hydrochloride injections for pain associated with the procedure. We replicated the design of the previously published study and performed a multicenter, double-blind, randomized, placebo-controlled trial to assess whether the extraordinary effects of MB on pain intensity could be confirmed. The primary outcomes were treatment success defined as at least 30% reduction in pain intensity and the Patients' Global Impression of Change 6 months after the intervention. We included 84 patients with CD-LBP of which 14 (35%) in the MB plus lidocaine group showed treatment success compared with 11 (26.8%) in the control group who received placebo plus lidocaine (P = 0.426). Twenty-seven percent of all participants treated with MB stated that their overall health improved much or very much (Patients' Global Impression of Change), vs 25.6% in the placebo group (P = 0.958). We were unable to confirm that intradiscal MB injections are better capable of significantly reducing pain in patients with CD-LBP 6 months after treatment compared with placebo. We observed that over one-quarter of patients receiving only lidocaine injections reported treatment success, which is in contrast with the previously published study. Our results do not support the recommendation of using intradiscal MB injections for patients with CD-LBP.