title: Effect of Intradiscal Methylene Blue Injection for the Chronic Discogenic Low Back Pain: One Year Prospective Follow-up Study.
abstract: OBJECTIVE
  To evaluate the efficacy of intradiscal methylene blue (MB) injection in patients with chronic discogenic low back pain.
  
  
  METHODS
  Twenty patients with discogenic low back pain (4 males, 16 females; mean age 45.6 years) refractory to conservative management were recruited. All subjects underwent MB injection in target lumbar intervertebral discs confirmed by provocative discography. The clinical outcome was assessed by visual analog scale (VAS) and Oswestry disability index (ODI) at baseline and 1, 3, 6 and 12 months after treatment. Successful outcome was described as minimum of 2 points reduction in pain intensity compared with the baseline.
  
  
  RESULTS
  VAS and ODI significantly decreased after one injection. The average VAS and ODI were reduced significantly from 5.1 and 38.0 at baseline to 3.2 and 27.4 at 3 months after injection (p<0.05). However, the mean score of VAS at 12 month follow-up was 4.5 and we could not observe any difference between 12 months after injection and pretreatment. Eleven of twenty patients (55%) reported successful outcomes after intradiscal MB injection at 3 month follow up and the average VAS was reduced by 3.3±1.1 (p<0.05). At the time of 12 month follow up, pain had relapsed in 6 patients who have had satisfactory effect at 3 month follow up. Successful outcome was maintained in only 5 patients (20%) for 1 year.
  
  
  CONCLUSIONS
  The intradiscal MB injection is a short-term effective minimally invasive treatment indicated for discogenic back pain but it may lose its effectiveness long-term.
authors.affiliation: Department of Physical Medicine and Rehabilitation, College of Medicine, Yeungnam University, Daegu 705-717, Korea.
authors.forename: Soo-Hyun
authors.initials: SH
authors.lastname: Kim
authors.forename: Sang-Ho
authors.initials: SH
authors.lastname: Ahn
authors.forename: Yun-Woo
authors.initials: YW
authors.lastname: Cho
authors.forename: Dong-Gyu
authors.initials: DG
authors.lastname: Lee