Assessing Offset Analgesia through electrical stimulations in healthy volunteers

Assessing Offset Analgesia through electrical stimulations in healthy volunteers 178Scientific presentations at the 2017 Annual Meeting / Scandinavian Journal of Pain 16 (2017) 165–188heat pain (HP) stimuli were assessed by visual analogue scale (VAS)and adjusted to elicit approximately 70/100 mm. Alternately pulsestimulations (pulse duration of 40 s; 0.025 Hz) which consisted ofCP, HP, or neutral temperature (32 ◦ C) were applied. Four conditions were tested and subjective sensations were assessed: (1) oneQTSD was applied to non-dominant forearm and cold-heat pulsestimulation was applied.Two QTSDs were applied to (2) non-dominant ipsilateral forearm with 5 cm apart, (3) non-dominant and contralateral forearms,(4) non-dominant forearm and ipsilateral thigh, respectively. Inconditions of (2)–(4), CP-neutral pulse stimulation (C-Neutral) andneutral-HP pulse stimulation (Neutral-H) were applied simultaneously with opposite phase, respectively.Results: CP and HP were 3.9 ± 1.0 ◦ C (mean ± SD) and43.6 ± 0.9 ◦ C (mean ± SD), respectively. The VAS values for CPand HP were 73.4 ± 2.0 mm (mean ± SD) and 76.4 ± 4.8 mm(mean ± SD), respectively. Some subjects could not discriminatecold or heat sensation and some felt cold as heat (paradoxical sensation). The number of subjects with such paradoxical sensation in(1), (2), (3), (4) were 9 (45%), 2 (10%), 0 (0%) and 3 (15%), respectively.Conclusions: In healthy volunteers, simultaneous alternatelycold-heat pulse stimulation on one site triggered paradoxical thermal sensation, which to a much less degree is triggered whenC-Neutral and Neutral-H were applied to different dermatomes.This suggests that the mechanism is primarily triggered peripherally.Acknowledgements: This work was supported by Grants-inAid for Scientific Research (No. 15K20975 and 15K20972) from theJapan Society for the Promotion of Science. There is no conflict ofinterest.http://dx.doi.org/10.1016/j.sjpain.2017.04.039Assessing Offset Analgesia through electricalstimulations in healthy volunteersD. Ligato ∗ , K.K. Petersen, C.D. Mørch, L.Arendt-NielsenCenter for Sensory-Motor Interaction (SMI),Department of Health Science Technology (HST),Aalborg University, Aalborg, DenmarkE-mail address: LAN@hst.aau.dk (D. Ligato).Background and aims: Offset Analgesia (OA) is a disproportionally large decrease of pain perception evoked by a slight decreaseof a painful cutaneous heat stimulus, resulting in a lower painperception compared to a simple constant stimulus at the sametemperature. This study aimed to investigate the possibility ofevoking the same disproportional analgesic effect by applying electrical stimuli.Methods: 24 subjects underwent two control-trials of 30 s constant intensity by applying either heat stimulation at 48 ◦ C oran electrical stimulation at 150% of the individual electrical PainDetection (ePD) on the volar forearm. OA-trials consisted of a 30 sstimulation, divided into three periods: T1 (5 s), T2 (5 s), and T3(20 s), with stimuli intensities of 48 ◦ C, 49 ◦ C and 48 ◦ C or 150% ofePD, 180% of ePD, and 150% of ePD.Subjects were asked to rate the pain intensity on an electronicVisual Analog Scale (VAS; 0: no pain; 10: worst imaginable pain),and were categorized as responders if they showed more than30% lower VAS at heat OA-trials compared to heat control-trial.Repeated measures Analysis of Variance was applied to investigatethe difference in pain intensity to the electrical OA-trials, comparedwith the electrical control-trials.Results: Responders to the heat OA-trial also responded to theelectrical OA-trial compared to the electrical control-trial, with ananalgesic effect of 3.3 ± 0.5 VAS points (P < 0.001). However, whenanalyzing all subjects, no difference was found comparing the electrical OA-trial (VAS 3.8 ± 0.5) to the electrical control-trial (VAS6.2 ± 0.4; P > 0.5).Conclusions: This study suggests that responders to the heatOA-paradigm also respond to the electrical OA-paradigm.http://dx.doi.org/10.1016/j.sjpain.2017.04.040Metastatic lung cancer in patient withnon-malignant neck pain: A case reportW.Z. Pawlak ∗ , L. Svensson, P.F. JensenMultidisciplinary Pain Centre, Department ofAnaesthesia, Næstved Hospital, DenmarkE-mail address: wzp@regionsjaelland.dk (W.Z. Pawlak).Background: Symptoms from disseminated cancer can developvery slowly. This could be very difficult to distinguish those symptoms from chronic disabilities and nuisances in patients withchronic non-malignant pain.Objective: In this report, the case of a woman with both nonmalignant pain and cancer is presented.Case report: A 54 years old woman was referred by a general practitioner to Multidisciplinary Pain Center. The diagnosiswas chronic non-malignant neck pain on the basis of degenerativecolumnar disease. The patient was also suffering from osteoporosis. During the first visit in the Center, the patient complained ofshooting pains in the neck and had tingling sensations in the fingers – most of his right hand. Moreover, the patient experiencedshooting pains in the hips, lower back and spine. The multidisciplinary treatment with medication, physical therapy, TENS andcognitive behavioral therapy was offered. Paracetamol togetherwith gabapentin was used. The patient experienced relief of pain.The doses of gabapentin was escalated up to 2400 mg daily without significant side effects. Afterwards, the dose was graduallyincreased to 3600 mg daily and the patient experienced fatigue,mild headache and dizziness. These symptoms were initiallyinterpreted as side effects of gabapentin. However, the tinglingsensations in the fingers were almost disappeared. The doses ofgabapentin was reduced, but without relief of symptoms. Within 2weeks, the patient developed partial paresis of the right upper limband aphasia. The patient was urgently referred to the neurologicinpatient clinic. CT- and MR-scans showed multiple cerebral metastases. Under the diagnostic workup the lung tumor was found. Thebiopsy showed pulmonary adenocarcinoma.Conclusions: The symptoms of lung cancer with cerebral metastases can mimic side effects of gabapentin.http://dx.doi.org/10.1016/j.sjpain.2017.04.041 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Scandinavian Journal of Pain de Gruyter

Assessing Offset Analgesia through electrical stimulations in healthy volunteers

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© 2017 Scandinavian Association for the Study of Pain
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10.1016/j.sjpain.2017.04.040
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Abstract

178Scientific presentations at the 2017 Annual Meeting / Scandinavian Journal of Pain 16 (2017) 165–188heat pain (HP) stimuli were assessed by visual analogue scale (VAS)and adjusted to elicit approximately 70/100 mm. Alternately pulsestimulations (pulse duration of 40 s; 0.025 Hz) which consisted ofCP, HP, or neutral temperature (32 ◦ C) were applied. Four conditions were tested and subjective sensations were assessed: (1) oneQTSD was applied to non-dominant forearm and cold-heat pulsestimulation was applied.Two QTSDs were applied to (2) non-dominant ipsilateral forearm with 5 cm apart, (3) non-dominant and contralateral forearms,(4) non-dominant forearm and ipsilateral thigh, respectively. Inconditions of (2)–(4), CP-neutral pulse stimulation (C-Neutral) andneutral-HP pulse stimulation (Neutral-H) were applied simultaneously with opposite phase, respectively.Results: CP and HP were 3.9 ± 1.0 ◦ C (mean ± SD) and43.6 ± 0.9 ◦ C (mean ± SD), respectively. The VAS values for CPand HP were 73.4 ± 2.0 mm (mean ± SD) and 76.4 ± 4.8 mm(mean ± SD), respectively. Some subjects could not discriminatecold or heat sensation and some felt cold as heat (paradoxical sensation). The number of subjects with such paradoxical sensation in(1), (2), (3), (4) were 9 (45%), 2 (10%), 0 (0%) and 3 (15%), respectively.Conclusions: In healthy volunteers, simultaneous alternatelycold-heat pulse stimulation on one site triggered paradoxical thermal sensation, which to a much less degree is triggered whenC-Neutral and Neutral-H were applied to different dermatomes.This suggests that the mechanism is primarily triggered peripherally.Acknowledgements: This work was supported by Grants-inAid for Scientific Research (No. 15K20975 and 15K20972) from theJapan Society for the Promotion of Science. There is no conflict ofinterest.http://dx.doi.org/10.1016/j.sjpain.2017.04.039Assessing Offset Analgesia through electricalstimulations in healthy volunteersD. Ligato ∗ , K.K. Petersen, C.D. Mørch, L.Arendt-NielsenCenter for Sensory-Motor Interaction (SMI),Department of Health Science Technology (HST),Aalborg University, Aalborg, DenmarkE-mail address: LAN@hst.aau.dk (D. Ligato).Background and aims: Offset Analgesia (OA) is a disproportionally large decrease of pain perception evoked by a slight decreaseof a painful cutaneous heat stimulus, resulting in a lower painperception compared to a simple constant stimulus at the sametemperature. This study aimed to investigate the possibility ofevoking the same disproportional analgesic effect by applying electrical stimuli.Methods: 24 subjects underwent two control-trials of 30 s constant intensity by applying either heat stimulation at 48 ◦ C oran electrical stimulation at 150% of the individual electrical PainDetection (ePD) on the volar forearm. OA-trials consisted of a 30 sstimulation, divided into three periods: T1 (5 s), T2 (5 s), and T3(20 s), with stimuli intensities of 48 ◦ C, 49 ◦ C and 48 ◦ C or 150% ofePD, 180% of ePD, and 150% of ePD.Subjects were asked to rate the pain intensity on an electronicVisual Analog Scale (VAS; 0: no pain; 10: worst imaginable pain),and were categorized as responders if they showed more than30% lower VAS at heat OA-trials compared to heat control-trial.Repeated measures Analysis of Variance was applied to investigatethe difference in pain intensity to the electrical OA-trials, comparedwith the electrical control-trials.Results: Responders to the heat OA-trial also responded to theelectrical OA-trial compared to the electrical control-trial, with ananalgesic effect of 3.3 ± 0.5 VAS points (P < 0.001). However, whenanalyzing all subjects, no difference was found comparing the electrical OA-trial (VAS 3.8 ± 0.5) to the electrical control-trial (VAS6.2 ± 0.4; P > 0.5).Conclusions: This study suggests that responders to the heatOA-paradigm also respond to the electrical OA-paradigm.http://dx.doi.org/10.1016/j.sjpain.2017.04.040Metastatic lung cancer in patient withnon-malignant neck pain: A case reportW.Z. Pawlak ∗ , L. Svensson, P.F. JensenMultidisciplinary Pain Centre, Department ofAnaesthesia, Næstved Hospital, DenmarkE-mail address: wzp@regionsjaelland.dk (W.Z. Pawlak).Background: Symptoms from disseminated cancer can developvery slowly. This could be very difficult to distinguish those symptoms from chronic disabilities and nuisances in patients withchronic non-malignant pain.Objective: In this report, the case of a woman with both nonmalignant pain and cancer is presented.Case report: A 54 years old woman was referred by a general practitioner to Multidisciplinary Pain Center. The diagnosiswas chronic non-malignant neck pain on the basis of degenerativecolumnar disease. The patient was also suffering from osteoporosis. During the first visit in the Center, the patient complained ofshooting pains in the neck and had tingling sensations in the fingers – most of his right hand. Moreover, the patient experiencedshooting pains in the hips, lower back and spine. The multidisciplinary treatment with medication, physical therapy, TENS andcognitive behavioral therapy was offered. Paracetamol togetherwith gabapentin was used. The patient experienced relief of pain.The doses of gabapentin was escalated up to 2400 mg daily without significant side effects. Afterwards, the dose was graduallyincreased to 3600 mg daily and the patient experienced fatigue,mild headache and dizziness. These symptoms were initiallyinterpreted as side effects of gabapentin. However, the tinglingsensations in the fingers were almost disappeared. The doses ofgabapentin was reduced, but without relief of symptoms. Within 2weeks, the patient developed partial paresis of the right upper limband aphasia. The patient was urgently referred to the neurologicinpatient clinic. CT- and MR-scans showed multiple cerebral metastases. Under the diagnostic workup the lung tumor was found. Thebiopsy showed pulmonary adenocarcinoma.Conclusions: The symptoms of lung cancer with cerebral metastases can mimic side effects of gabapentin.http://dx.doi.org/10.1016/j.sjpain.2017.04.041

Journal

Scandinavian Journal of Painde Gruyter

Published: Dec 29, 2017

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