Comparison of the hypoalgesic efficacy of low-frequency and burst-modulated kilohertz frequency currents.

BACKGROUND AND PURPOSE A within-subject randomized controlled trial was conducted to compare monophasic pulsed current (PC) with a frequency of 50 Hz and a phase duration of 500 microseconds with burst-modulated alternating current (BMAC) (1-kHz alternating current, burst modulated at a frequency of 50 Hz with a 20% duty cycle) to establish whether there were differences in hypoalgesic efficacy as assessed by cold pain threshold measurements. SUBJECTS Twenty-two young adults who were healthy and drawn from a population of students of La Trobe University volunteered to participate in the study. Nineteen subjects (7 male, 12 female) met the inclusion criteria. METHOD Each participant experienced monophasic PC and BMAC. Time to cold pain threshold was measured before, during, and after the electrical stimulation intervention. RESULTS Both PC and BMAC currents were effective at elevating the cold pain threshold, although there was no statistically significant difference between the 2 currents during stimulation. DISCUSSION AND CONCLUSION Pulsed current and BMAC appear to be equally effective at elevating the cold pain threshold. Analysis indicated that if any real difference exists, it would only be apparent with large (100) subject numbers. Any differences in hypoalgesic efficacy thus are not likely to be clinically important.