Occipital nerve stimulation for chronic migraine: a randomized trial on subthreshold stimulation.

INTRODUCTION Occipital nerve stimulation (ONS) may provide pain relief in migraine patients. In this double-blinded trial we investigated the significance of paresthesia and possible placebo effects. METHODS Patients already treated with ONS reporting stable treatment effect were included. "Effective stimulation," "subthreshold stimulation" and "no stimulation" were compared. Patients cycled through all three treatment groups. Outcome was measured using the visual analog scale (VAS) for pain, McGill Pain Questionnaire and SF-36. RESULTS Eight patients were included, mean preoperative VAS was 8.20 ± 1.22. A significant improvement in pain was observed in favor of suprathreshold stimulation compared to subthreshold stimulation (1.98 ± 1.56 vs 5.65 ± 2.11). Pain also significantly improved under subthreshold stimulation compared to no stimulation (5.65 ± 2.11 vs 8.45 ± 0.99). No changes in SF-36 were observed. CONCLUSIONS Paresthesia is not required to achieve pain reduction but suprathreshold stimulation yields better results, underlining the significance of stimulation parameter customization.