Spasticity management is pivotal for achieving functional recovery of stroke patients. The purpose of this study was to investigate the effects of a single trial of transcutaneous electrical nerve stimulation (TENS) on spasticity and balance in chronic stroke patients. Forty-two chronic stroke patients were randomly allocated into the TENS (n = 22) or the placebo-TENS (n = 20) group. TENS stimulation was applied to the gastrocnemius for 60 min at 100 Hz, 200 μs with 2 to 3 times the sensory threshold (the minimal threshold in detecting electrical stimulation for subjects) after received physical therapy for 30 min. In the placebo-TENS group, electrodes were placed but no electrical stimulation was administered. For measuring
spasticity, the resistance encountered during passive muscle stretching of ankle joint was assessed using
the Modified Ashworth Scale, and the Hand held dynamometer was used to assess the resistive force
caused by spasticity. Balance ability was measured using a force platform that measures postural sway
generated by postural imbalance. The TENS group showed a significantly greater reduction in spasticity of
the gastrocnemius, compared to the placebo-TENS group (p < 0.05). TENS resulted in greater balance
ability improvements, especially during the eyes closed condition (p < 0.05). However, these effects
returned to baseline values within one day. This study shows that TENS provides an immediately effective
means of reducing spasticity and of improving balance in chronic stroke patients. The present data may be
useful to establish the standard parameters for TENS application in the clinical setting of stroke.