Efficacy of Transcranial Magnetic Stimulation (TMS) in Chronic Idiopathic Pain Disorders

• Average pain over the last 24 hours at each visit -pain diary at baseline to see the stability of the measures [ Time Frame: at each visit before the stimulation session ] [ Designated as safety issue: No ]
  Brief Pain inventory
  
  

• Sensory and affective pain scores (McGill pain questionnaire) [ Time Frame: at baseline, then day 1, 5, weeks 3, 9, and 25 after the induction phase ] [ Designated as safety issue: No ]
  Short form MPQ was used
  
  
• Quality of life (brief pain inventory) [ Time Frame: at baseline, days 1, 5,weeks 3, 9, and 25 after the induction phase ] [ Designated as safety issue: No ]
  Brief Pain inventory (Cleeland and Ryan 1992) interference items (7)
  
  
• Disability ( FIQ) [ Time Frame: at days 1, 5, weeks 3, 9 and 25 after the induction phase ] [ Designated as safety issue: No ]
  FIQ only for fibromyalgia patients
  
  
• Comorbidities (HAD) [ Time Frame: at week 3 7, 13, 25 after the induction phase ] [ Designated as safety issue: No ]
  21 item Hospital anxiety and depression scale
  
  
• Catastrophizing (PCS) [ Time Frame: at weeks 3, 7, 13 and 25 after the induction phase ] [ Designated as safety issue: No ]
  Pain Catastrophizing Scale (Sullivan et al 1995)
  
  
• Predictors of the response based on psychological factors and measures of cortical excitability [ Time Frame: at inclusion ] [ Designated as safety issue: No ]
  
• Safety including cognitive evaluation [ Time Frame: at 6 months (cognitive evaluation) ; safety assessed every month for up to 12 months ] [ Designated as safety issue: Yes ]
  Cognitive tests were performed by a neuropsychologists and included measures of attention and memory
  
  
• Comparison of the efficacy of TMS between 3 different pain disorders [ Time Frame: during the whole study period -ie, days 1, 5, then before each stimulation throughout the study ] [ Designated as safety issue: No ]
  this can only be made when the two other groups of patients will have finished the enrollment - for now the study on fibromyalgia is finished and results analysed - the other groups are still being recruited (ie, IBS, burning mouth syndrome)
  
  
• assessment of cortical excitability [ Time Frame: day 1, 5, weeks 3, 9 and 21 after the induction phase ] [ Designated as safety issue: No ]
  determination of rest motor threshold, suprathreshold motor evoiked potentials (MEP), SICI and ICF, for the left hemisphere
  
  

Several lines of evidence suggest that fibromyalgia syndrome, Irritable Bowel syndrome (IBS) and burning mouth syndrome are chronic pain disorders affecting pain modulation. Repetitive transcranial magnetic stimulation (rTMS) is a recent, safe and non-invasive technique for stimulating the cerebral cortex, which has recently been reported to induce short term analgesic effects in patients with chronic focal pain. We have also recently shown in a double blind randomized trial, that rTMS could have short term analgesic effects in patients with fibromyalgia.

Objectives : Our aim is to investigate the long term analgesic effects of repeated sessions of unilateral rTMS in patients with chronic pain syndrome due to fibromyalgia, IBS or burning mouth syndrome. Primary outcome will be numerical pain scores on brief pain inventory at each visit.

Methods : This study will be randomized and performed in parallel groups and double blind versus sham stimulation. It will include at least 30 patients per pain disorder, ie 90 patients. Randomization will be computerized and performed for each of the aetiological groups separately (ie, there will be 3 distinct randomization procedures for fibromyalgia, IBS and stomatodynia);. Stimulation will be applied to the right motor area corresponding to the contralateral hand. The treatment will consist in a first period of 5 consecutive days of stimulation, followed by a stimulation once a week during 3 weeks then a stimulation twice a month during 2 months then stimulation once a month during 3 additional months. Clinical assessment will be performed at baseline, then at day 1, 5, weeks 3, 5, 7, 9, 13 and 25. It will include depending on the visits an assessment of pain intensity and characteristics, quality of life, sleep, depression and anxiety, catastrophizing, and a brief neuropsychological evaluation (focusing on memory, attention and vigilance). In patients with fibromyalgia, the evaluation will also include specifically the number of tender points. In patients with IBS, evaluation of bowel dysfunction will also be performed.

Conclusion : This study should allow to determine for the first time the long term efficacy and safety of rTMS in the treatment of dysfunctional or idiopathic chronic pain syndromes which are often refractory to conventional treatments.