High-frequency rTMS using a double cone coil for gait disturbance

It is difficult to stimulate leg motor areas with magnetic current using a figure-of-eight coil due to the deep anatomical location of the areas. However, a double cone coil is useful for stimulating deep brain regions. We postulated that the use of the same coil may allow repetitive transcranial magnetic stimulation (rTMS) to modulate the neural activity of the same areas. The purpose of this study is to investigate the effect of high-frequency rTMS applied over bilateral leg motor areas with a double cone coil on walking function after stroke.

Eighteen post-stroke hemiparetic patients with gait disturbances attended two experimental sessions with more than 24 h apart, in a cross-over, double-blind paradigm. In one session, high-frequency rTMS of 10 Hz was applied over the leg motor area bilaterally in a 10-s train using a double cone coil for 20 min (total 2,000 pulses). In the other session, sham stimulation was applied for 20 min at the same site. To assess walking function, walking velocity, and Physiological Cost Index (PCI) were evaluated serially before, immediately after, and 10 and 20 min after each stimulation.

The walking velocity was significantly higher for 20 min after stimulation in the high-frequency rTMS group than the sham group. PCI was lower in the high-frequency rTMS group than the sham group, but this was significant only immediately after stimulation.

High-frequency rTMS of bilateral leg motor areas using a double cone coil can potentially improve walking function in post-stroke hemiparetic patients.