Cheing 2005.

Study characteristics
Methods	Type of study: double blind, placebo‐controlled, parallel RCT. Condition and number of participants randomised:  clinical diagnosis of hypersensitive hands due to peripheral nerve injuries (N = 19). Groups: TENS group (N = 10); placebo group (N = 9).
Participants	Demographics: N = 19, mean 35 yrs, range 15 to 58 yrs, 16 male/3 female. TENS group, 32 ± 11 yrs; placebo group, 38 ± 13 yrs (mean ± SD). Setting: outpatients. Inclusion: people who complained of hypersensitive hands within or adjacent to the site of the injury, and who were able to complete the VAS independently. Exclusion: people who had general manifestations of pain as seen in causalgia or shoulder‐hand syndrome; people who had received any TENS or undergone a desensitization programme 1 month prior to the trial; cardiac pacemaker or who had experienced sensory loss in their hands prior to the trial. Withdrawals/dropouts: not detailed.
Interventions	Where applied: in hospital. Applied by: presume by clinician. Waveform: square pulses. Frequency: 100 Hz. Pulse duration: 200 μs. Pulse amplitude/Intensity: adjusted to produce a tingling sensation that was strong but tolerable. Placebo Group: procedures identical to those for TENS group, except that a sham unit was used. Internal circuit of the sham TENS unit disconnected but the indicator lamp lit when unit switched on. All participants told that they might or might not feel a tingling sensation during Rx. Electrodes: 2 rectangular carbon rubber electrodes with gel, 2 cm x 3 cm, anode applied directly over the hypersensitive area and cathode placed proximally along the distribution of the same peripheral nerve. Duration and frequency of Rx: 20 mins, 10 Rxs. Device/manufacturer: 120Z TENS unit (ITO, Tokyo). Adverse effects: not detailed.
Outcomes	Pain outcome: pain intensity using VAS for a brush‐evoked stimulus with a toothbrush. Recorded before Rx on days 1, 4, 7 and 11. ITT/per protocol analysis: not detailed. Statistical analysis: no evaluable data for this review as mixed age population (adults and children). Significantly lower pain scores were found in the TENS group than in the placebo group by Day 7 and Day 11. Both groups demonstrated significant decreases in VAS scores across treatment sessions.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"Subjects were matched by age, history of developing hypersensitivity and baseline VAS scores, and then randomly assigned into either the TENS (n = 10) or placebo group (n = 9) by drawing lots".
Allocation concealment (selection bias)	Unclear risk	No details provided.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No details provided.
Source of funding bias	Unclear risk	No details provided.
Blinding (Participant)	High risk	It is impossible to adequately blind participants who receive electrical stimulation. "All subjects were blind to group allocation. The placebo group had received no active treatment (just placebo TENS) throughout the trial. The treatment procedures for the placebo group were identical to those for the real TENS group, except that a sham unit was used. The appearance of the sham unit was identical to that of a real TENS unit, but the internal circuit of the sham TENS unit was disconnected. When the machine was switched on, there was no output of current, but the indicator lamp lit up. All subjects were told that they might or might not feel a tingling sensation during the treatment". "People who had received any TENS" was an exclusion criteria.
Blinding (Outcome Assessor)	Low risk	"The blinded assessor repeatedly practiced applying the same brushing force on a digital balance prior to the study".
Sample Size	High risk	TENS (N =10); placebo (N = 9).