Electrical Intra-cutaneous Half-sine Stimulation for Optimized Preferential C-fiber Activation

Part I: Threshold detection and Flare response: 6 pulses of 25 ms half-sine are given at 2 Hz each, increasing current intensity (mA) until detection threshold, pain threshold and pain level (3 out of 10 NRS) are reached. Determined intensity values reapplied during 214 impulses. Line scan to visualize changes in local skin blood flow done. Part II: Hyperalgesia, Allodynia, Pain and flare response of 65 minutes. Baseline assessment of local skin perfusion and spatial extent of allodynia by using cotton swab and pinprick hyperalgesia. Current intensity is reapplied, adjusted until pain level of 6 reached. After 5 minutes axon reflex flare, allodynia and secondary hyperalgesia are measured and repeated proximal every 10 minutes with last measurement after 65 minutes. In first 15 minutes current intensity is adapted to maintain NRS level of 6. During this 65 minutes' period, 25 ms half-sine is administered continuously.

Part I: Threshold detection and Flare response: 6 pulses of 500 µs rectangular shaped stimulation are given at 2 Hz each, increasing current intensity (mA) until detection threshold, pain threshold and pain level (3 out of 10 NRS) are reached. Determined intensity values reapplied during 214 impulses. Line scan to visualize changes in local skin blood flow done. Part II: Hyperalgesia, Allodynia, Pain and flare response of 65 minutes. Baseline assessment of local skin perfusion and spatial extent of allodynia by using cotton swab and pinprick hyperalgesia. Current intensity is reapplied, adjusted until pain level of 6 reached. After 5 minutes axon reflex flare, allodynia and secondary hyperalgesia are measured and repeated proximal every 10 minutes with last measurement after 65 minutes. In first 15 minutes current intensity is adapted to maintain NRS level of 6. During this 65 minutes' period, 500 µs rectangular shaped stimulation is administered continuously.