The effects of transcutaneous electrical nerve stimulation (TENS) on spasticity in multiple sclerosis

Spasticity is a common and often disabling symptom associated with multiple sclerosis (MS). Transcutaneous electrical nerve stimulation (TENS) has been found effective in reducing spasticity in conditions such as stroke, but there is little evidence to support its use in MS. The aim of this study was to evaluate the effectiveness of TENS on spasticity in MS and, furthermore, to compare two different application times. Thirty-two subjects were randomized into two groups, and a single, blind, crossover design was used to compare two weeks of 60 minutes and 8 hours daily of TENS applications (100 Hz and 0.125 ms pulse width). Outcomes were examined using the Global Spasticity Score (GSS), the Penn Spasm Score (PSS), and a visual analogue scale (VAS) for pain. The results of the study demonstrated that there were no statistically significant differences in the GSS following either 60 minutes or 8 hours daily of TENS (P=0.433 and 0.217, respectively). The 8-hour application time led to a significant reduction in muscle spasm (P=0.038) and pain (P = 0.008). Thus, this study suggests that, whilst TENS does not appear to be effective in reducing spasticity, longer applications may be useful in treating MS patients with pain and muscle spasm.