Safety and Characterization of a Novel Multi-Channel TMS Stimulator

Background:

Stimulator technology has not changed significantly since the early days of TMS. Stimulation of a single-element coil using the sole channel of a TMS stimulator is standard.

Objective:

In this study, Roth et al. demonstrate the feasibility of a novel multi-channel stimulator device for which the stimulation parameters of each channel are independently controllable.

Methods:

A prototype of this device was assembled with 5 independent channels and a variety of multi-element coils were tested, including those based on deepH-coil design characteristics.

Results:

Significant improvements in stimulation efficiency and coil heating were demonstrated. For example, a 70% reduction of energy dissipated as heat for a 4-channel coil in comparison to a standard single-element (figure-8) coil.

Conclusions:

Furthermore, the flexibility of the multi-channel stimulator enables novel combinations of pulse characteristics and timings. For example, inter-pulse intervals for the technique of paired pulse TMS were demonstrated in the range of 0-1ms, that is impossible to achieve with any other stimulator design known today. The use of this unique range of pulse intervals to exploit a well-known neurophysiological phenomenon indicated the exciting potential of a new approach for achieving enhanced depth penetration with reduced stimulation of intermediate tissues.

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