Table 2 RSS treatment parameters and key findings from included articles

Celnik et al., 2007 [12]

2

2

One-off session of RSS

Each train = 5 pulses of 1-ms duration delivered at 10 Hz

2 electrode bars to stimulate ulnar and median nerves

1 h and 24 h post-test

RSS reduced JTFTH (seconds) at 1 (44.9 ± 8.2) and 24 h (43.57 ± 7.9) post-test (p < 0.5)

Conforto et al., 2010 [11]

24

2

3 days a week for 1 month (total of 12 sessions)

Each train = 5 pulses of 1-ms duration delivered at 10 Hz (sub/suprasensory)

2 electrode bars to stimulate median nerve

1 month and 2–3 months

RSS reduced JTHFT (seconds)

1 month: Subsensory: 49.5 ± 5.1

Suprasensory: 61.4 ± 4.9 at 1 month (p < 0.05)

3 months: Subsensory: 64.7 ± 5.2

Suprasensory: 54.6 ± 4.8 (ns)

Conforto et al., 2007 [29]

2

2

One-off session of RSS

1-ms duration delivered at 10 Hz

Surface electrodes to stimulate median nerve

Immediately after RSS and 1 month later

JTHFT (modified)

ANOVA showed significant improvements after RSS in comparison to control with respect to the intervention (p < 0.001) and time (p < 0.0001).

Conforto et al., 2002 [30]

2

2

One-off session of RSS

Each train = 5 pulses of 1-ms duration delivered at 10 Hz

Surface electrodes to stimulate median nerve

Immediately after/24 h after RSS

Increased pinch muscle strength seen following RSS (+ 2.41 ± 0.7 N p = 0.017). No comparison between control and RSS group.

Ghaziani, et al. 2018 [10]

12.5

1

Daily throughout hospital stay (max 4 weeks)

Suprasensory:

Continuous delivery of 10 Hz pulse width 250 μs subsensory: 10 Hz devlivered over 3 s every 2.5 min pulse width 250 μs, frequency = 10 H

Surface electrodes on wrist, elbow, and shoulder.

Post intervention and 6 months

No statistically significant differences between the sub and supra-sensory groups at any time point for any outcome measure.

Box and block test (blocks/min)

Subsensory, after treatment: 19.9 ± 16.2, follow up: 26.7 ± 16.7

Suprasensory: 25.9 ± 15.7,

Effect size after treatment {95%CI]: − 0.8 [− 3.9, 2.3], .at follow-up: − 0.5 [− 5.2, 4.1].

Kattenstroth et al., 2018 [31]

7.5

0.75

5 days a week for 2 weeks

Each train delivered at 20 Hz burst for 1.4 s with 5 s inter-train intervals

Glove with built in electrodes contacting each finger tip

Mean 2.9 ± 1.4 days.

Significant differences in grip strength (Kg) after the intervention between sham and RSS groups.

RSS: 20.2 ± 12.3 Sham: 21.3 ± 10.9 (p < 0.05)

Klaiput et al., 2009 [13]

2

2

One-off session of RSS

Each train = 5 pulses of 1-ms duration delivered at 10 Hz for 500 ms

Carbon rubberised electrodes overlaying ulnar and median nerve sites

Immediately after RSS only

Significant improvements compared to sham in lateral and tip pinch strength (pounds):

Lateral: RSS: 14.1 ± 4.9 Sham: 12.9 ± 2.3 (p < 0.001) Tip: RSS: 10.8 ± 3.6

Sham: 9.8 ± 2.2 (p < 0.02)

Peurala et al., 2002 [32]

14.7

2 × 0.33 day

3-week inpatient period. Average 21.6 ± 6 sessions

Monophasic constant current twin pulses at 50 Hz.

Glove or shock electrode (wrist)

Unclear

?immediately after 3 week period only

MMAS - not compared to non-stimulated control:

MMAS hand sensation (reported in RSS group only): Pre: 11.2 ± 6

Post: 13.7 ± 4 p < 0.01