Papers of the Week

The aim of the present study was to compare the efficacy of burst-like conditioning electrical stimulation versus continuous stimulation of cutaneous nociceptors for inducing increased pinprick sensitivity in the surrounding unstimulated skin (a phenomenon referred to as secondary hyperalgesia). In a first experiment (N=30) we compared the increase in mechanical pinprick sensitivity induced by 50 Hz burst-like stimulation (N=15) versus 5 Hz continuous stimulation (N=15), while maintaining constant the total number of stimuli and the total duration of stimulation. We found a significantly greater increase in mechanical pinprick sensitivity in the surrounding unstimulated skin after 50 Hz burst-like stimulation compared to 5 Hz continuous stimulation (=.013, Cohen's =.970). Importantly, to control for the different frequency of stimulation we compared in a second experiment (N=40) 5 Hz continuous stimulation (N=20) versus 5 Hz burst-like stimulation (N=20), this time while keeping the total number of stimuli as well as the frequency of stimulation identical. Again we found a significantly greater increase in pinprick sensitivity after 5 Hz burst-like stimulation compared to 5 Hz continuous stimulation (=.009, Cohen's =.868). To conclude, our data shows indicate that burst-like conditioning electrical stimulation is more efficacious than continuous stimulation for inducing secondary hyperalgesia.