title: Lidocaine patch (5%) is no more potent than placebo in treating chronic back pain when tested in a randomised double blind placebo controlled brain imaging study.
abstract: BACKGROUND
  The 5% Lidocaine patch is used for treating chronic neuropathic pain conditions such as chronic back pain (CBP), diabetic neuropathy and complex regional pain syndrome, but is effective in a variable proportion of patients. Our lab has reported that this treatment reduces CBP intensity and associated brain activations when tested in an open labelled preliminary study. Notably, effectiveness of the 5% Lidocaine patch has not been tested against placebo for treating CBP. In this study, effectiveness of the 5% Lidocaine patch was compared with placebo in 30 CBP patients in a randomised double-blind study where 15 patients received 5% Lidocaine patches and the remaining patients received placebo patches. Functional MRI was used to identify brain activity for fluctuations of spontaneous pain, at baseline and at two time points after start of treatment (6 hours and 2 weeks).
  
  
  RESULTS
  There was no significant difference between the treatment groups in either pain intensity, sensory and affective qualities of pain or in pain related brain activation at any time point. However, 50% patients in both the Lidocaine and placebo arms reported a greater than 50% decrease in pain suggesting a marked placebo effect. When tested against an untreated CBP group at similar time points, the patch treated subjects showed significantly greater decrease in pain compared to the untreated group (n = 15).
  
  
  CONCLUSIONS
  These findings suggest that although the 5% Lidocaine is not better than placebo in its effectiveness for treating pain, the patch itself induces a potent placebo effect in a significant proportion of CBP patients.
authors.affiliation: Department of Physiology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois 60611, USA.
authors.forename: Javeria A
authors.initials: JA
authors.lastname: Hashmi
authors.forename: Marwan N
authors.initials: MN
authors.lastname: Baliki
authors.forename: Lejian
authors.initials: L
authors.lastname: Huang
authors.forename: Elle L
authors.initials: EL
authors.lastname: Parks
authors.forename: Mona L
authors.initials: ML
authors.lastname: Chanda
authors.forename: Thomas
authors.initials: T
authors.lastname: Schnitzer
authors.forename: A Vania
authors.initials: AV
authors.lastname: Apkarian
mesh_terms: D001416:Back Pain / Q000188:drug therapy* / Q000503:physiopathology; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D059350:Chronic Pain / Q000188:drug therapy* / Q000503:physiopathology; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008012:Lidocaine / Q000008:administration & dosage / Q000627:therapeutic use*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D059906:Neuroimaging; D015990:Placebo Effect; D057968:Transdermal Patch
chemical_list: D008012:Lidocaine