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452 Inhibition of cortical laser evoked potentials by transcutaneous electrical nerve stimulation
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Poster Presentations / Human studies / European Journal of Pain 11(S1) (2007) S59–S207
and pain tolerance thresholds to heat, cold and pressure. Pain rating scales include Pain Castastrophizing Scale, Coping Strategies Questionnaire and McGill Pain Questionnaire. Anxiety and depression are measured with Symptom Checklist-92, Hamilton Depression and Anxiety Rating Scales, Major Depression Inventory, Anxiety Inventory GAD-10 and SF-36 Health Survey. The patients are compared to 25 age- and gender-matched healthy controls. Results. Data collection is ongoing. Preliminary results will be ready for presentation at the conference. doi:10.1016/j.ejpain.2007.03.465
ceptive plasticity, and easily overrides competing homosynaptic LTD. (Supported by DFG-Tr236/16-2 & BMBF-01EM0506). doi:10.1016/j.ejpain.2007.03.466
452 INHIBITION OF CORTICAL LASER EVOKED POTENTIALS BY TRANSCUTANEOUS ELECTRICAL NERVE STIMULATION G. Jonker *,a, C.F. Van Swol b, D. Brandsma c, E.H. Boezeman c, H.P.A. Van Dongen a, H.J.A. Nijhuis a a
451 SPATIAL AND TEMPORAL STIMULUS PARAMETERS OF CONDITIONING STIMULATION AFFECT THE MAGNITUDE AND DIRECTION OF HUMAN PAIN PLASTICITY R.M. Gracien *, W. Magerl, T. Klein, R.-D. Treede Institute of Physiology and Pathophysiology, Johannes Gutenberg University Mainz, Germany Memory-like long-term potentiation (LTP) and depression (LTD) rule nociceptive plasticity. In a recently established model of LTP- and LTD-like bidirectional plasticity of human pain perception [Klein et al., J Neurosci 2004; 24: 964–71.] we investigated the impact of variations in spatial and temporal stimulus parameters on the magnitude and direction of plasticity. The skin of the thigh was stimulated through a multipolar electrode array (? 30 mm area, 48 pin electrodes) with 500 or 1000 conditioning electrical pulses at 1, 10 and 100 Hz in 12 healthy human volunteers (intensity: 10· detection threshold). LTP magnitude grew linearly with the frequency of conditioning stimulation (significantly different between frequencies, at least p < 0.05). Longer pulse trains (1000 pulses) tended to give stronger LTP (p = 0.07). Unexpectedly, LTD-like responses at low frequency (1 Hz) were never seen. Testing at the conditioned and an adjacent (unconditioned) test site revealed highly correlated responses of similar magnitude (r = 0.91) suggesting that heterosynaptic facilitation was the dominant underlying process at both test sites. The direction and magnitude of the response depended significantly on the number of electrodes and on the size of the stimulated skin area. Namely, stimulation through a small 10 pin electrode resulted in significant LTD, while stimulation through the large 48 pin electrode resulted in significant LTP. We conclude that spatial and temporal stimulus parameters affect the magnitude and direction of pain plasticity. Heterosynaptic facilitation leading to frequency-dependent LTP plays a substantial role in noci-
Department of Anaesthesiology, Intensive Care and Pain Medicine, St. Antonius Hospital, Nieuwegein, The Netherlands b Department of Medical Physics, St. Antonius Hospital, Nieuwegein, The Netherlands c Department of Clinical Neurophysiology, St. Antonius Hospital, Nieuwegein, The Netherlands Introduction. Laser evoked potentials (LEPs), consisting of a N2 and P2 component are seen in the EEG 175– 500 ms after laser stimulation of the skin. The amplitude of LEP relates to subjective pain rating. With transcutaneous electrical nerve stimulation (TENS) tactile afferent input is thought to inhibit nociceptive processing. Are LEP characteristics a means to evaluate the effects of TENS? Methods. With a 980 nm diode laser, 10 stimuli (0.25– 0.6 W, 50 ms) were delivered to the blackened dorsum of the hand of 13 volunteers and averaged offline. Area under the curve (AUC175 – 500 ms) and total amplitude of N2 and P2 (N2–P2) were calculated. TENS (110 Hz) was applied to the dorsolateral forearm. LEPs were recorded following 1 and 10 min of TENS and 10 min after stopping TENS. For each stimulus, the intensity of pain was recorded on a numeric rating scale (NRS: 0–10, 0: no pain, 10: worst imaginable pain). Results. A significant reduction in the AUC175 – 500 ms was found after 10 min of TENS (mean reduction 26%; 95% CI: 1.2–50.4), but not after 1 min of TENS. The AUC reduction remained significant 10 min after stopping TENS (mean decrease 28%, 95% CI:3.0–52.9). There was no reduction in N2P2 during or after TENS. The mean NRS decreased by 1 point (range 2.5 to 3) during TENS. Ten min after stopping TENS, the mean NRS increased by 1 point (range 0–2). Conclusions. TENS is accompanied by a significant reduction in AUC of LEP. doi:10.1016/j.ejpain.2007.03.467
Poster Presentations / Human studies / European Journal of Pain 11(S1) (2007) S59–S207
and pain tolerance thresholds to heat, cold and pressure. Pain rating scales include Pain Castastrophizing Scale, Coping Strategies Questionnaire and McGill Pain Questionnaire. Anxiety and depression are measured with Symptom Checklist-92, Hamilton Depression and Anxiety Rating Scales, Major Depression Inventory, Anxiety Inventory GAD-10 and SF-36 Health Survey. The patients are compared to 25 age- and gender-matched healthy controls. Results. Data collection is ongoing. Preliminary results will be ready for presentation at the conference. doi:10.1016/j.ejpain.2007.03.465
ceptive plasticity, and easily overrides competing homosynaptic LTD. (Supported by DFG-Tr236/16-2 & BMBF-01EM0506). doi:10.1016/j.ejpain.2007.03.466
452 INHIBITION OF CORTICAL LASER EVOKED POTENTIALS BY TRANSCUTANEOUS ELECTRICAL NERVE STIMULATION G. Jonker *,a, C.F. Van Swol b, D. Brandsma c, E.H. Boezeman c, H.P.A. Van Dongen a, H.J.A. Nijhuis a a
451 SPATIAL AND TEMPORAL STIMULUS PARAMETERS OF CONDITIONING STIMULATION AFFECT THE MAGNITUDE AND DIRECTION OF HUMAN PAIN PLASTICITY R.M. Gracien *, W. Magerl, T. Klein, R.-D. Treede Institute of Physiology and Pathophysiology, Johannes Gutenberg University Mainz, Germany Memory-like long-term potentiation (LTP) and depression (LTD) rule nociceptive plasticity. In a recently established model of LTP- and LTD-like bidirectional plasticity of human pain perception [Klein et al., J Neurosci 2004; 24: 964–71.] we investigated the impact of variations in spatial and temporal stimulus parameters on the magnitude and direction of plasticity. The skin of the thigh was stimulated through a multipolar electrode array (? 30 mm area, 48 pin electrodes) with 500 or 1000 conditioning electrical pulses at 1, 10 and 100 Hz in 12 healthy human volunteers (intensity: 10· detection threshold). LTP magnitude grew linearly with the frequency of conditioning stimulation (significantly different between frequencies, at least p < 0.05). Longer pulse trains (1000 pulses) tended to give stronger LTP (p = 0.07). Unexpectedly, LTD-like responses at low frequency (1 Hz) were never seen. Testing at the conditioned and an adjacent (unconditioned) test site revealed highly correlated responses of similar magnitude (r = 0.91) suggesting that heterosynaptic facilitation was the dominant underlying process at both test sites. The direction and magnitude of the response depended significantly on the number of electrodes and on the size of the stimulated skin area. Namely, stimulation through a small 10 pin electrode resulted in significant LTD, while stimulation through the large 48 pin electrode resulted in significant LTP. We conclude that spatial and temporal stimulus parameters affect the magnitude and direction of pain plasticity. Heterosynaptic facilitation leading to frequency-dependent LTP plays a substantial role in noci-
Department of Anaesthesiology, Intensive Care and Pain Medicine, St. Antonius Hospital, Nieuwegein, The Netherlands b Department of Medical Physics, St. Antonius Hospital, Nieuwegein, The Netherlands c Department of Clinical Neurophysiology, St. Antonius Hospital, Nieuwegein, The Netherlands Introduction. Laser evoked potentials (LEPs), consisting of a N2 and P2 component are seen in the EEG 175– 500 ms after laser stimulation of the skin. The amplitude of LEP relates to subjective pain rating. With transcutaneous electrical nerve stimulation (TENS) tactile afferent input is thought to inhibit nociceptive processing. Are LEP characteristics a means to evaluate the effects of TENS? Methods. With a 980 nm diode laser, 10 stimuli (0.25– 0.6 W, 50 ms) were delivered to the blackened dorsum of the hand of 13 volunteers and averaged offline. Area under the curve (AUC175 – 500 ms) and total amplitude of N2 and P2 (N2–P2) were calculated. TENS (110 Hz) was applied to the dorsolateral forearm. LEPs were recorded following 1 and 10 min of TENS and 10 min after stopping TENS. For each stimulus, the intensity of pain was recorded on a numeric rating scale (NRS: 0–10, 0: no pain, 10: worst imaginable pain). Results. A significant reduction in the AUC175 – 500 ms was found after 10 min of TENS (mean reduction 26%; 95% CI: 1.2–50.4), but not after 1 min of TENS. The AUC reduction remained significant 10 min after stopping TENS (mean decrease 28%, 95% CI:3.0–52.9). There was no reduction in N2P2 during or after TENS. The mean NRS decreased by 1 point (range 2.5 to 3) during TENS. Ten min after stopping TENS, the mean NRS increased by 1 point (range 0–2). Conclusions. TENS is accompanied by a significant reduction in AUC of LEP. doi:10.1016/j.ejpain.2007.03.467