Longlasting antalgic effects of daily sessions of repetitive transcranial magnetic stimulation in central and peripheral neuropathic pain

Background and objective: A single session of repetitive transcranial magnetic stimulation (rTMS) over motor cortex had been reported to produce short term relief of some types of chronic pain. The present study investigated whether five consecutive days of rTMS would lead to longer lasting pain relief in unilateral chronic intractable neuropathic pain. Patients and methods: Forty eight patients with therapy resistant chronic unilateral pain syndromes (24 each with trigeminal neuralgia (TGN) and post-stroke pain syndrome (PSP)) participated. Fourteen from each group received 10 minutes real rTMS over the hand area of motor cortex (20 Hz, 10x10 s trains, intensity 80% of motor threshold) every day for five consecutive days. The remaining patients received sham stimulation. Pain was assessed using a visual analogue scale (VAS) and the Leeds assessment of neuropathic symptoms and signs (LANSS) scale, before, after the first, fourth, and fifth sessions, and two weeks after the last session. Results: No significant differences were found in basal pain ratings between patients receiving real- and sham-rTMS. However, a two factor ANOVA revealed a significant "± TMS" x "time" interaction indicating that real and sham rTMS had different effects on the VAS and LANSS scales. Post hoc testing showed that in both groups of patients, real-rTMS led to a greater improvement in scales than sham-rTMS, evident even two weeks after the end of the treatment. No patient experienced adverse effects. Conclusion: These results confirm that five daily sessions of rTMS over motor cortex can produce longlasting pain relief in patients with TGN or PSP.