Deymed DuoMAG QPS*

Quadripulse Monophasic TMS

The DuoMAG Quadripulse System (QPS) combines four DuoMAG MP stimulators to provide a fully configurable quadripulse TMS stimulator. This combination allows individual control of the amplitude of all stimulators as well as the capability of setting inter stimulus interval (ISI) and delivering the defined quadripulse TMS through a single coil.

The quadripulse functionality allows users to deliver precise sub- and supra-threshold conditioning and test pulses which is a vital component when studying Inter- and Intra-Cortical Inhibition and Facilitation. The inter stimulus interval for the four pulses is adjustable either in the supplied control software or external control via TTL inputs, offering the ultimate flexibility in ISI control.

DuoMAG MP-Quad allows users to combine the four stimulator pulses into a single pulse providing a pulse amplitude that equates to 140% of a single DuoMAG MP output. The DuoMAG MP-Quad can also be used with four separate coils to carryout interhemispheric (quadrilateral) stimulation.

"Regular rTMS (repetitive application of single pulses at a single frequency, e.g. 1 Hz or 20 Hz) is already known to show some long-term effects. In addition, theta burst stimulation (TBS) is already important but its effect are not that robust and sometimes variable. QPS was derived from studies that showed that repetitive paired-pulse stimulation could evoke some long-term effects. The concept of QPS was to increase the number of pulses to four.

The technique was created around the same time as theta burst to try and develop a stimulation paradigm that had a more robust, less variable results. With QPS, the effect off stimulation is larger but the duration is similar. The most important part is the low variability. This means that we can induce the expected effect very reproducibly. There is less variability with the QPS technique than there is with the theta burst technique." Professor Ugawa, pioneer of the QPS.