Methylene blue in the treatment of discogenic low back pain.

BACKGROUND The personal and societal impact of chronic low back pain is considerable. The intervertebral disc is considered the etiologic source in up to 40% of patients, with considerable previous efforts directed at developing reliable and efficacious treatments. Recent publications, including a double-blind, randomized, placebo-controlled trial, using a one-time treatment of methylene blue, showed statistically significant, clinically relevant improvements in pain and function in the treatment groups. The postulated mechanism of action of methylene blue is denervation of small nociceptive fibers that grow into the annulus fibrosis, which are implicated in discogenic pain. STUDY DESIGN Retrospective case series. SETTING Academic pain management center. OBJECTIVES To examine the outcomes for a cohort of patients treated with methylene blue for discogenic pain, discuss potential differences in selection and administration protocols and briefly review other proposed treatments for discogenic pain (e.g. intradiscal electrothermy therapy, intradiscal steroids, intradiscal biaccuplasty, rami communicans radiofrequency thermocoagulation, and chymopapain). METHODS This case series examines the pain and functional outcomes in 8 patients treated with a one-time administration of methylene blue for discogenic back pain. Follow-up information was available between 2 months and over one year, depending on the patient. RESULTS Application of this treatment for these 8 patients for discogenic pain diagnosed by provocation discography showed only one clinical success at our center. Four patients had a time-limited clinical response in pain and/or function between 2 weeks and 5 months. Patient specific data are outlined in detail herein. CONCLUSIONS Low back pain ascribed to a discogenic source continues to be an elusive clinical entity to treat. We have reserved further treatment of methylene blue for discogenic pain until other controlled trials have been published. LIMITATIONS A case series.