Difference in Pain and Discomfort of Comparable Wrist Movements Induced by Magnetic or Electrical Stimulation for Peripheral Nerves in the Dorsal Forearm

Figures & data

Figure 1 Stimulus instruments.

Notes: Left is rPMS and right is TES. Both instruments were portable and easy to use.

Abbreviations: rPMS, repetitive peripheral magnetic stimulation; TES, transcutaneous electrical current stimulation.

Table 1 Experimental Conditions

	Conditions
	TES	rPMS
Stimulation intensity	From 1 mA to endurable value: 1) 1 mA lower than the intensity associated with a pain or discomfort score of 10 or 2) 3 mA greater than the intensity reaching the angle of maximum voluntary movement of the wrist	10 levels from 10% to 100% of the maximum stimulus intensity
Stimulation frequency	30 Hz	30 Hz
Pulse width	300 µs	350 µs
Stimulation and pause time	2 sec, 8 sec	2 sec, 8 sec
Stimulus count	4 times	4 times

Notes: Stimulus parameters (frequency, pulse width, stimulation and pause time, stimulus count) were set as same as possible.

Abbreviations: rPMS, repetitive peripheral magnetic stimulation; TES, transcutaneous electrical current stimulation.

Figure 2 Definitions of the analytical parameters.

Abbreviations: AS, analysis section from 0 to 2 seconds; σ, integral value of wrist joint angle during; deg, degree.

Figure 3 An example of a subject’s regression curve using the sigmoid function.

Notes: (A) is rPMS and (B) is TES. X-axis shows stimulus intensity, which the unit of rPMS is “%” and it of TES is “mA”. Y-axis shows iROM, which the units are “°s”. Both rPMS and TES condition, stimulus intensity and iROM were strongly correlated using by regression curve of sigmoid function.

Abbreviations: rPMS, repetitive peripheral magnetic stimulation; TES, transcutaneous electrical current stimulation; iROM (°s), integrated range of movement (degree multiplied by second).

Figure 4 Pain caused by the differences in the integral value of the wrist movements and the stimulus conditions.

Notes: The two-factor repeated measures analysis of variance (ANOVA) revealed significant main effects with respect to both the types of stimulus devices and the iROM. ×, mean value; -, median value; *p < 0.05; **p < 0.01.

Abbreviations: NRS, numerical rating scale; iROM (°s), integrated range of movement (degree multiplied by second); rPMS, repetitive peripheral magnetic stimulation; TES, transcutaneous electrical current stimulation.

Figure 5 Discomfort caused by the differences in the integral value of the wrist movements and the stimulus conditions.

Notes: The two-factor repeated measures analysis of variance (ANOVA) revealed significant main effects with respect to both the types of stimulus devices and the iROM. ×, mean value; -, median value; *p < 0.05; **p < 0.01.

Abbreviations: NRS, numerical rating scale; iROM (°s), integrated range of movement (degree multiplied by second); rPMS, repetitive peripheral magnetic stimulation; TES, transcutaneous electrical current stimulation.