Effectiveness of Repetitive Transcranial Magnetic Stimulation in Patients With Failed Back Surgery Syndrome: A Double-Blind Randomized Placebo-Controlled Study.

Background: Failed back surgery syndrome (FBSS) is the term of persistent back and/or leg pain after lumbar surgery. Repetitive transcranial magnetic stimulation (r-TMS) is a technique that allows noninvasive and relatively painless stimulation of cerebral cortex. It can reduce the experience of chronic pain by producing the small electrical currents in the cortex via magnetic field.
Objectives: The aim of this study is to determine the effectiveness of r-TMS treatment on patients with FBSS.
Study Design: A double-blind, randomized, placebo-controlled trial.
Setting: The Physical Medicine and Rehabilitation Clinic of Istanbul Fatih Sultan Mehmet Training and Research Hospital, Istanbul, Turkey.
Methods: In this double-blinded, randomized, placebo-controlled trial, 20 patients (aged 34-65 years) clinically diagnosed as FBSS who had a history of surgery for lumbar disc herniation with persistent back and leg pain were reviewed. Only patients with no root compression and/or spinal stenosis in postoperative magnetic resonance imaging of lumbar spine were included. Patients were randomly assigned to r-TMS (n:10) and sham (n:10) groups. Patients in the r-TMS group received 5 Hz of r-TMS as a 20-minute (1,000 pulses) daily session, 5 days per week, for a total of 10 sessions. r-TMS was applied with MagVenture device (MagPro X100, Denmark, 2009) and figure 8 coil (MMC 140 parabolic, MagVenture). Control group received sham r-TMS with the same protocol. Each patient was evaluated at baseline, days 5 and 10 of treatment, and 1 and 3 months after treatment. Visual Analog Scale (VAS), DN4 (Douleur Neuropathique en 4 Questions), Oswestry Disability Index (ODI), Beck Depression Inventory (BDI), and the Pittsburgh Sleep Quality Index (PSQI) were used for evaluation.
Results: There were no statistically significant differences between the groups for age, gender, number of surgeries, pain duration, working status, and drug usage. Significant improvements were achieved in DN4, ODI, BDI, and PSQI scores in the r-TMS group in comparison to the sham group. Both groups displayed improvements in VAS scores, whereas improvement in the sham group was limited to the first month. Achieved improvements in the r-TMS group in terms of VAS, DN4, ODI, BDI, and PSQI scores were sustained at the third month.
Limitations: The limited number of patients and the short follow-up periods are the main limitations of our study. Further placebo-controlled studies with longer follow-up periods and greater number of cases would be beneficial for examining r-TMS application as a new treatment option in patients with FBSS.
Conclusions: r-TMS might be an effective alternative treatment in patients with FBSS, further studies with larger groups are needed.