Frequency-dependent effects of sine-wave cranial transcutaneous electrical nerve stimulation in human subjects

In a double-blind protocol, ninety healthy volunteer subjects received 30 minutes of constant current sine-wave cranial transcutaneous electrical nerve stimulation (TENS) of 5 Hertz (Hz), 100 Hz, or 2000 Hz frequency (current maintained below .5 mA for safety), placebo TENS, or no treatment. The five groups were compared on pre- to posttreatment changes in blood pressure, heart rate, peripheral temperature, and anxiety. Analysis showed significant reductions in systolic and diastolic blood pressure and heart rate after 100 Hz cranial TENS as compared to the other groups. No other differences achieved significance.