Robot-Guided Neuronavigated Repetitive Transcranial Magnetic Stimulation (rTMS) in Central Neuropathic Pain.

Objectives: To confirm and extend previous results involving repetitive transcranial magnetic stimulation (rTMS) aimed at alleviating refractory central neuropathic pain (CNP). To evaluate pain relief in detail and to assess ongoing benefits after one year of treatment.

Design: Prospective observational study.

Setting: University hospital. Outpatient settings.

Participants: Patients (N=80) with chronic central pain after brain or spinal cord injuries.

Interventions: High-frequency (20Hz) neuronavigated-rTMS sessions were applied on the primary motor cortex using a figure-of-eight coil positioned by a robotized arm. Patients received a minimum of 4 consecutive sessions, each separated by 3-4 weeks.

Main Outcome Measures: Percentage of pain relief (%R), duration of pain relief (DPR), numeric rating scale (NRS), neuropathic pain symptom inventory (NPSI), and pain relief score (PRS).

Results: Seventy-one patients completed the study. On average, after the first 4 sessions, %R was 28% and DPR was 11 days. Fifty-four patients (76%) were responders with a permissive threshold of ≥10%R and 61% (43 patients) with a stringent threshold ≥30%R. After 12 months of treatment (15 sessions) we observed a cumulative effect on %R (48%), DPR (20d), and on the prevailing NPSI sub-score (-28%). This effect reached significance after 4 sessions and was further maintained over 12 months. Across participants, more than 1000 rTMS sessions were delivered over 6 years without any adverse effect.

Conclusion: These results confirm that multiple rTMS sessions are both safe and have potential as a treatment for CNP. An ongoing randomized controlled trial will allow teasing out of this effect from placebo analgesia.