title: Effects of methylene blue on postoperative low-back pain and functional outcomes after lumbar open discectomy: a triple-blind, randomized placebo-controlled trial.
abstract: OBJECTIVE
  Despite advances in surgical and anesthesiology techniques, many patients continue to experience postoperative pain after lumbar disc operations. This study aims to investigate the effects of methylene blue (MB) on preventing postoperative low-back pain (LBP) with or without radicular pain and improving the quality of life (QOL) in patients undergoing lumbar open discectomy.
  
  
  METHODS
  This is a prospective, randomized, triple-blind, placebo-controlled clinical trial, which was conducted at Shiraz University of Medical Sciences between July 2011 to January 2012. Of a total of 130 patients, 115 were eligible for participation; 56 received 1 ml of MB solution at a concentration of 0.5% (MB group) and 59 received an equivalent volume of normal saline (control group). Primary outcomes were the control of LBP with or without radicular pain, which was evaluated preoperatively and at 24 hours and 3 months after surgery with the use of a visual analog scale (VAS), and the improvement of QOL, which was assessed preoperatively and 3 months postoperatively by means of the Persian translation of the Oswestry Disability Index questionnaire.
  
  
  RESULTS
  The mean VAS scores for LBP were significantly lower in the MB group compared with the control group at 24 hours (1.25 ± 0.97 vs 2.80 ± 0.69, p < 0.001) and 3 months (1.02 ± 1.29 vs 2.07 ± 1.10, p = 0.019) after treatment. The mean radicular pain scores decreased significantly in the 2 groups at 24 hours after surgery, but the mean radicular pain score was significantly lower in the MB-treated patients than the control group. However, the difference between radicular pain scores in the MB group (1 ± 1.1) and the control group (1.2 ± 1) was not statistically significant (p = 0.64). The reduction in LBP was greater in the MB group than the control group (8.11 ± 1.74 vs 6.07 ± 1.52, p = 0.023, CI 95% -1.37 to -0.10). The functional QOL improved significantly 3 months after the operation in both groups (p < 0.001). Moderate disability occurred more frequently in the control group than in the MB group (14.5% vs 7.7%, p = 0.004). No toxicity, adverse effects, or complications were found in the group of patients treated with MB injection.
  
  
  CONCLUSIONS
  A single dose of MB (1 ml 0.5%) for coating the dura and surrounding tissues (facet and muscle) shows promising results in terms of safety, reduction of postoperative pain, and functional outcome compared with placebo.
authors.affiliation: Shiraz Neuroscience Research Center and Neurosurgery Department, and.
authors.forename: Majid Reza
authors.initials: MR
authors.lastname: Farrokhi
authors.affiliation: Radiology Department, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Mehrzad
authors.initials: M
authors.lastname: Lotfi
authors.affiliation: Shiraz Neuroscience Research Center and Neurosurgery Department, and.
authors.forename: Mohammad Sadegh
authors.initials: MS
authors.lastname: Masoudi
authors.affiliation: Shiraz Neuroscience Research Center and Neurosurgery Department, and.
authors.forename: Mehrnaz
authors.initials: M
authors.lastname: Gholami
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D004185:Disability Evaluation; D017586:Diskectomy / Q000379:methods; D005260:Female; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000601:surgery; D017116:Low Back Pain / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D008751:Methylene Blue / Q000494:pharmacology*; D008875:Middle Aged; D011446:Prospective Studies; D011788:Quality of Life; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D008751:Methylene Blue
keywords: 5-HT = 5-hydroxytryptamine (serotonin); BMI = body mass index; LBP = low-back pain; MAO = monoamine oxidase; MB = methylene blue; ODI = Oswestry Disability Index; QOL = quality of life; SSRI = selective serotonin reuptake inhibitor; ST = serotonin toxicity; VAS = visual analog scale; low-back pain; lumbar discectomy; methylene blue; postoperative pain; quality of life