title: Action potential simulation (APS) in patients with fibromyalgia syndrome (FMS): a controlled single subject experimental design.
abstract: OBJECTIVE
  Action potential simulation (APS) is becoming a popular method of pain reduction. Nevertheless, little is known about the efficacy of this relatively new treatment. The aim of this study was to investigate whether APS helps to reduce pain, improves patients' perception of daily functioning and social participation in patients with fibromyalgia syndrome (FMS).
  
  
  METHODS
  Ten patients with FMS according to the American College of Rheumatology (ACR) criteria entered this double blind crossover single-case study. In a period of 20 weeks, the patients underwent two treatment periods of 4 weeks, one with verum and one with placebo, at random, in a double blind fashion. Outcome measures were evaluated on a weekly basis. Primary outcome measure was pain measured with the Fibromyalgia Impact Questionnaire (FIQ) questions 4 and 5, the number of tender points and the total tender point pain intensity score. Both visual inspection and statistical analysis were done to analyse the data from this single-subject design.
  
  
  RESULTS
  Performing visual inspection and statistical analysis, no positive results of the APS treatment were found in this study. Remarkable is the fact that placebo APS had significantly better results than verum APS.
  
  
  CONCLUSIONS
  In this single-case study with ten patients (all female), APS was not a helpful method to reduce pain, to improve patients' perception of daily functioning and social participation in patients with FMS.
authors: Rudolf Magnus Institute of Neuroscience, Department of Neurology and Neurosurgery, Section Rehabilitation, University Medical Center Utrecht, Heidelberglaan, The Netherlands. rfengler@umcutrecht.nl
authors: R K B
authors: RK
authors: Fengler
authors: J W G
authors: JW
authors: Jacobs
authors: M
authors: M
authors: Bac
authors: A J M
authors: AJ
authors: van Wijck
authors: N L U
authors: NL
authors: van Meeteren