Spinal Magnetic Stimulation in Neuropathic Pain

SMS was delivered with a repetitive magnetic stimulator connected to a figure of eight coil capable of delivering a maximum output of 2 Tesla per pulse. The coil measured 90 mm in each wing and was centered over the surface landmark corresponding to the cauda equina region. SMS was performed with the patient lying comfortably in the prone position and a soft pillow supported the lower abdomen. The coil was placed flat over the back with the handle pointing cranially. Each patient on active treatment received 200 trains of 5 pulses delivered at 10 Hz, at an interval of 5 s between each train. As this was a pilot study, each only received 1000 pulses in a single session.

The placebo arm consisted of 'sham' SMS delivered with the coil angled vertically and one of the wing edges in contact with the stimulation point. As this coil type allows maximum magnetic flux at the center of the intersection, we believe minimum or no stimulation was effected at the edge of the coil in contact with the patient. Stimulation parameters and duration were unchanged in this arm.