Transcutaneous electrical nerve stimulation and transcutaneous spinal electroanalgesia: A preliminary efficacy and mechanisms-based investigation
published online 16 July 2009.
Abstract
Objectives
To determine the effects of transcutaneous electrical nerve stimulation (TENS) and transcutaneous spinal electroanalgesia (TSE) on mechanical pain threshold (MPT) and vibration threshold (VT).
Design
A prospective, single-blind, randomised, placebo-controlled trial.
Setting
Laboratory based.
Participants
Thirty-four healthy volunteers (12 men and 22 women; mean age±standard deviation 30±8 years). Exclusion criteria were conditions affecting upper limb sensation and contraindications to electrical stimulation.
Interventions
Participants were allocated at random to receive TENS (n=8), TSE (n=8), placebo (n=9) or control (n=9). Electrical stimulation was applied for 30minutes (from time 18minutes to 48minutes) via electrodes (5cm×5cm) placed centrally above and below the space between the C6 and C7 spinous processes, with 5cm between electrodes.
Main outcome measures
MPT (using an algometer) and VT (using a vibrameter) were recorded on seven occasions from the first dorsal interosseous muscle of the right hand – at baseline (0minutes) and then at 10-minute intervals until the end of the 60-minute testing period.
Results
There were no statistically significant group differences in MPT (all p>0.05). Significant group differences in VT were found at 20, 30 and 40minutes (all p<0.05). Post-hoc tests showed that the TENS group had significantly greater VT than both the placebo [median difference 0.30μm, 95% confidence interval (CI) −0.05 to 0.66] and control (0.51μm, 95% CI 0.05 to 0.97) groups at 20minutes, and significantly greater VT than the control group (0.69μm, 95% CI 0.20 to 1.17) at 30minutes (all p<0.008).
Conclusions
Electrical stimulation did not alter MPT. The increase in VT during TENS may be due to distraction or antidromic block of large-diameter nerve fibres. TSE failed to alter either outcome measure significantly.
ABSTRACT