Erica Suzan - Academia.edu (original) (raw)

Papers by Erica Suzan

<p>Patients’ recruitment flowchart.</p

<p>Apomorphine/placebo effects on spontaneous pain and on pain evoked by cold stimulation i... more <p>Apomorphine/placebo effects on spontaneous pain and on pain evoked by cold stimulation in the painful leg.</p

PLOS ONE, 2018

CONSORT 2010 checklist of information to include when reporting a randomised trial* Section/Topic... more CONSORT 2010 checklist of information to include when reporting a randomised trial* Section/Topic Item No Checklist item Reported on page No Title and abstract 1a Identification as a randomised trial in the title 1 1b Structured summary of trial design, methods, results, and conclusions (for specific guidance see CONSORT for abstracts) 2-3

Journal of Pain Research, 2017

Background: People often state that they are "sensitive" or "insensitive" to pain. However, the a... more Background: People often state that they are "sensitive" or "insensitive" to pain. However, the accuracy and clinical relevance of such statements is unclear. Objective: The aim of this study was to search for associations between self-perception of sensitivity to pain and experimental pain measures, including known psychophysical inhibitory or excitatory pain paradigms. Subjects and methods: Subjective sensitivity to pain was reported by 75 healthy participants and included three self-perceived variables: pain threshold, pain sensitivity and pain intensity in response to a hypothetical painful event (hypothetical pain intensity [HPI]). Experimental pain measures consisted of thermal pain threshold (°C), suprathreshold thermal pain intensity (Visual Analog Scale, 0-100) and the psychophysical paradigms of conditioned pain modulation (CPM) and temporal summation (TS), representing inhibitory and excitatory pain processes, respectively. Results: No significant correlations were found between self-perceived pain threshold or pain sensitivity and any of the experimental pain measures. In contrast, the reported HPI correlated with thermal pain threshold (r =-0.282; p = 0.014), suprathreshold thermal pain intensity (r = 0.367; p = 0.001) and CPM (r = 0.233; p = 0.044), but not with TS. Conclusion: Self-perception of pain sensitivity articulated by intangible expressions such as pain threshold or pain sensitivity is unrelated to actual sensitivity to experimental pain. In contrast, when measured by intensity of a hypothetical painful event (HPI), sensitivity to pain is associated with some, but not all, experimental pain reports. Further studies are needed for better understanding of these associations and their potential clinical significance.

The Clinical Journal of Pain, 2018

Objectives: Analgesic trials often fail to show a significant effect even when medications with k... more Objectives: Analgesic trials often fail to show a significant effect even when medications with known efficacy are tested. This could be attributed to insufficient assay sensitivity of analgesic trials, which may be due, in part, to the insensitivity of pain-related outcome measures. The aim of this methodological study was to assess the responsiveness of evoked pain generated by the staircase procedure compared with other commonly used pain outcomes in knee osteoarthritis. Methods: This was a randomized, double-blind, placebo-controlled, cross-over trial of 1-week treatment of naproxen versus placebo. Participants were assigned to one of the 2 treatment sequences (naproxen-placebo or placebo-naproxen). Pain-at-rest, evoked pain using the Staircase-Evoked Pain Procedure (StEPP), pain diary, and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) data were collected before and at the end of each treatment sequence. Results: A total of 55 osteoarthritis patients (30 M, 25 F) completed the study. Among all pain assessments, evoked pain was the most sensitive outcome to detect treatment effects, with Standardized Effect Size (SES) of 0.47 followed by the WOMAC and pain-at-rest with SES of 0.43 and 0.36, respectively. Sample size calculations demonstrated that compared with spontaneous pain, the evoked pain model reduces required number of subjects by 40%. Discussion: Study results support our hypothesis that evoked pain using the StEPP may demonstrate greater responsiveness to treatment effects compared with traditional pain-related outcome measures. Accordingly, these results may facilitate development and validation of other chronic pain-related evoked pain models, which could contribute to future research and development of new analgesics.

International journal of gynecological cancer : official journal of the International Gynecological Cancer Society, 2018

Uterine papillary serous carcinoma (UPSC) is a highly aggressive subtype of endometrial carcinoma... more Uterine papillary serous carcinoma (UPSC) is a highly aggressive subtype of endometrial carcinoma. Histopathologically, it resembles the pattern of serous papillary carcinoma of the ovary. Cancer antigen 125 (CA-125) is the most widely used biomarker in epithelial ovarian carcinoma. Its use in UPSC evaluation has yet to be determined. The purpose of this study was to investigate the significance of preoperative serum CA-125 as a prognostic factor in patients with UPSC. The study cohort included all women with UPSC operated in our institution between January 2002 and June 2016. All patients underwent complete surgical staging. Preoperative CA-125 was reviewed and correlated with clinical and pathological parameters. Sixty-one women met the study criteria. Median preoperative CA-125 was found to be significantly associated with disease stage. Patients with disease stages I to IV had median preoperative CA-125 levels of 12.15, 19.6, 22.6, and 177.5 U/mL (P < 0.0001) respectively. Le...

PAIN Reports, 2017

Introduction: We recently showed that the psycho-stimulant norepinephrine-dopamine reuptake inhib... more Introduction: We recently showed that the psycho-stimulant norepinephrine-dopamine reuptake inhibitor methylphenidate (MP) prolonged cold pain threshold and tolerance in adults with attention-deficit hyperactivity disorder (ADHD). Objectives: The objectives of the present study were to: (1) examine whether MP has antinociceptive properties in healthy men; (2) test MP's effects on responses to aversive auditory stimuli. The underlying aim was to determine whether MP exerts antinociceptive properties or more generalized, nonspecific attenuating effects on different aversive sensory modalities. Methods: This double-blind, crossover, randomized placebo-controlled study consisted of 2 sessions one week apart from each other. In each session, pain threshold (seconds) and tolerance (seconds) in response to painful cold stimulation were measured. Additionally, threshold (dB) and tolerance (seconds) to loud aversive auditory stimuli (500 Hz, 2000 Hz and white noise) were also tested prior to and 2 hours following the administration of a single dose of either 20 mg MP or an identical looking placebo. Results: Forty men, 26.1 6 4.0 (mean 6 SD) years were enrolled in the study. Wilcoxon signed-rank test analyses showed that MP, but not the placebo, produced a significant increase in cold pain threshold (from 4.1 6 2.6 to 5.4 6 3.1 seconds, P 5 0.001 and from 4.5 6 2.6 to 4.3 6 2.7 seconds, P 5 0.2, respectively) and tolerance (from 57.8 6 54.0 to 73.8 6 61.8 seconds, P 5 0.001 and from 52.5 6 53.7 sec to 57.0 6 52.9 seconds, P 5 0.1, respectively). No significant changes were found in any of the auditory parameters. Conclusion: These results suggest that MP has an effect on nociceptive pathways rather than a nonspecific, generalized attenuating effect on aversive sensory stimuli.

Journal of opioid management

Animal studies have shown that in addition to their antinociceptive effects, opioids have attenua... more Animal studies have shown that in addition to their antinociceptive effects, opioids have attenuated the electrophysiological "wind-up" phenomenon. Although effects of opioids on clinical pain and on temporal summation (TS), the human correlatives of this phenomenon, have been tested repeatedly, correlations between these two parameters have not been reported so far. To search for possible correlations between the effects of remifentanil on clinical pain intensity and on the magnitude of TS in patients with chronic pain. A single-blinded prospective study. A tertiary care pain clinic. Thirty-one patients (24 men) with chronic lumbar (radicular) neuropathic pain. Intervenous administration of saline followed by remifentanil infusions. Clinical pain intensity and thermal TS measured at baseline, during infusion of each drug and 20 minutes after termination of remifentnail infusion. Friedman test revealed statistically significant differences in the magnitudes of both clinica...

The Bone & Joint Journal, 2016

Aims Amputation in intractable cases of complex regional pain syndrome (CRPS) remains controversi... more Aims Amputation in intractable cases of complex regional pain syndrome (CRPS) remains controversial. The likelihood of recurrent Complex Regional Pain Syndrome (CRPS), residual and phantom limb pain and persistent disability after amputation is poorly described in the literature. The aims of this study were to compare pain, function, depression and quality of life between patients with intractable CRPS who underwent amputation and those in whom amputation was considered but not performed. s There were 19 patients in each group, with comparable demographic details. The amputated group included 14 men and five women with a mean age of 31 years (sd 12) at the time of CRPS diagnosis. The non-amputated group consisted of 12 men and seven women and their mean age of 36.8 years (sd 8) at CRPS diagnosis. The mean time from CRPS diagnosis to (first) amputation was 5.2 years (sd 4.3) and the mean time from amputation to data collection was 6.6 years (sd 5.8). All participants completed the fo...

Journal of pain research, 2015

A model for measuring temporal summation (TS) by tonic noxious stimulation was recently proposed.... more A model for measuring temporal summation (TS) by tonic noxious stimulation was recently proposed. However, methodological variations between studies make it difficult to reach a consensus regarding the way TS should be applied and calculated. The present study aimed to present a calculation method of TS magnitude produced by a tonic heat model in a large cohort of healthy subjects. Noxious heat stimulation (46.5°C/2 minutes) was applied to the forearm of 154 subjects who continuously rated pain intensity using a computerized visual analog scale. TS was calculated by "mean group" and "individual" approaches. A "typical" pattern of pain response, characterized by a peak pain followed by a decrease in intensity to a nadir and subsequently a progressive increase in pain scores, was exhibited by 86.4% of the subjects. Using the "mean group" and "individual" calculation approaches, the mean ± standard deviation magnitudes of TS were 31.4±2...

Pain physician, 2013

Opioids are the cornerstone therapy for the treatment of moderate to severe pain. Yet, unconfirme... more Opioids are the cornerstone therapy for the treatment of moderate to severe pain. Yet, unconfirmed evidence suggests that chronic exposure to opioids may cause hypersensitivity to pain, a phenomenon known as opioid-induced hyperalgesia (OIH). The current preliminary prospective study was aimed to explore the relationship between experimental OIH and clinical opioid induced analgesia (OIA) in a model of experimental OIH in patients with chronic radicular pain using intermediate-term opioid therapy. Prospective evaluation Interdisciplinary Pain Clinic at a referral Health Care Campus Thirty patients with chronic neuropathic (radicular) pain were assessed prior to and following 4 weeks of an individually titrated dose of oral hydromorphone treatment (4-20 mg/d). The assessments included an evaluation of experimental OIH by testing for heat pain intensity and cold pain tolerance and an assessment of OIA by completing pain and disability questionnaires. Hydromorphone was found to induce ...

Pain Medicine, 2014

Conditioned pain modulation (CPM) and offset analgesia (OA) are considered to represent paradigms... more Conditioned pain modulation (CPM) and offset analgesia (OA) are considered to represent paradigms of descending inhibitory pain modulation in humans. This study tested the effects of hydromorphone therapy on descending inhibitory pain modulation, as measured by changes from baseline in the magnitudes of CPM and OA. Prospective evaluation. Institute of Pain Medicine, Rambam Health Care Campus. Patients with chronic radicular pain. Thirty patients received 4 weeks of oral hydromorphone treatment at an individually titrated dose (mean ± standard deviation dose of 11.6 ± 4.8 mg/day). CPM and OA were assessed before and after hydromorphone treatment. CPM was assessed by subtracting the response to a painful phasic heat stimulus administered simultaneously with a conditioning cold pain stimulus, from the response to the same heat stimulus administered alone. The OA paradigm consisted of a three-temperature stimuli train (T1 = 49°C [5 seconds], T2 = 50°C [5 seconds], and T3 = 49°C [20 seconds]). The magnitude of OA was quantified by subtracting minimal pain scores obtained during T3 from the maximal pain scores obtained during T2. CPM scores changed from a baseline of 17.7 ± 20.6 to 21 ± 20.4 following treatment, and OA scores changed from 7.8 ± 20.5 to 9.7 ± 14.6. Wilcoxon signed rank test indicated that these changes were not significant (CPM: P = 0.22; OA: P = 0.44). McNemar test revealed that the percentage of patients who exhibited a change in the direction of CPM or OA in response to hydromorphone treatment was not significant (CPM: P = 0.37; OA: P = 0.48). These results suggest that the descending inhibitory pain modulation, as manifested in humans by CPM and OA, is unlikely to be mediated by hydromorphone therapy.

Pain Practice, 2014

The 0 to 100 mm visual analogue scale (VAS) and the five-category verbal rating scale (VRS) are c... more The 0 to 100 mm visual analogue scale (VAS) and the five-category verbal rating scale (VRS) are commonly used for measuring pain intensity. An open question remains as to whether these scales can be used interchangeably to allow comparisons between intensities of pain in the clinical setting or increased statistical power in pain research. Seven hundred and ninety-six patients were requested to rate the present intensity of their chronic pain on the two scales. Spearman&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s rank correlation coefficients between VAS and VRS were calculated. For testing interchangeability, VAS was transformed into a discrete ordinal scale by dividing the entire VAS into five categories, either equidistantly (biased) or using frequency distributions of VAS (unbiased). We used Goodman-Kruskal&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s gamma and Wilson&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s e measures of ordinal association quantified the relationships between the transformed VAS and VRS scores and Svensson method to evaluate agreement between biased and unbiased discrete VAS and VRS scales. Average VAS and VRS scores were 76 ± 18 mm and &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;severe,&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; respectively. Spearman&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s rank correlation coefficient values between continuous VAS and VRS were 0.77 to 0.85. Goodman-Kruskal&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s gamma ordinal associations between discrete VAS and VRS were 0.82 to 0.92 and 0.90 to 0.98 for the biased and unbiased VAS, respectively. Wilson&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s e measures were 0.51 to 0.61 and 0.54 to 0.65, accordingly. Svensson analysis showed low probability of agreement between both biased (0.66 to 0.76) and unbiased (0.75 to 0.82) VAS and VRS. Regardless of the relatively high Spearman correlations between original VAS and VRS, the low ordinal association and low probability of agreement between discrete VAS and VRS suggest that they are not interchangeable. Therefore, VAS and VRS should not be used interchangeably in the clinical setting or for increased statistical power in pain research.

Pain Practice, 2013

Evidence suggests tumor necrosis factor-alpha (TNF-α) mediates, at least in part, symptoms and si... more Evidence suggests tumor necrosis factor-alpha (TNF-α) mediates, at least in part, symptoms and signs in complex regional pain syndrome (CRPS). Here, we present a case series of patients with CRPS type 1, in whom the response to the anti-TNF-α adalimumab was assessed. Ten patients with CRPS type 1 were recruited. Assessments were performed before treatment, at 1 week, and 1, 3, and 6 months following 3 biweekly subcutaneous injections (40 mg/0.8 mL) adalimumab (Humira(®) ) and included the followings: Pain intensity using a 0-10 cm visual analog scale; the Short Form of the McGill Pain Questionnaire; the Beck Depression Inventory; the SF-36 questionnaire and mechanical and thermal thresholds (Von frey hair and Thermal Sensory Analyzer, respectively). In addition to the description of individual patient responses, both intention to treat (ITT) and per-protocol (PP) analyses were performed for the entire group. Three subgroups of patients were identified (3 patients in each): &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;nonresponders&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;, &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;partial responders&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;, and &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;robust responders&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; in whom improvement in almost all parameters was noted. Both the ITT and PP analyses demonstrated only a trend toward improvement in mechanical pain thresholds following treatment (ITT χ² = 13.83, P = 0.008; PP χ² = 10.29, P = 0.036). These results suggest adalimumab, and possibly other anti-TNF-α, can be potentially useful in some (although not in all) patients with CRPS type 1. These preliminary results along with the growing body of evidence which points to the involvement of TNF-α in the pathogenesis of CRPS justify further studies in this area.

PAIN, 2015

Evidence has shown that electrical stimulation at the dorsal columns attenuated the &amp;... more Evidence has shown that electrical stimulation at the dorsal columns attenuated the &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;wind-up&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; phenomenon in dorsal horn neurons in nerve-injured rats. This study was aimed to test the effect of spinal cord stimulation (SCS) on temporal summation (TS), the clinical correlate of the wind-up phenomenon in patients with radicular leg pain. Eighteen patients with SCS implants were tested both 30 minutes after SCS activation (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;ON&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;) and 2 hours after turning it off (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;OFF&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;), in a random order. Temporal summation was evaluated in the most painful site in the affected leg and in the corresponding area in the contralateral leg by applying a tonic painful heat stimulus (46.5°C; 120 seconds) and simultaneous recording of the perceived heat pain intensity. Patients were also requested to report their clinical pain intensity (0-100 numerical pain scale) during SCS &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;ON&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; and &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;OFF&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;. The Wilcoxon signed rank test was used in the comparisons between SCS &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;ON&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; and &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;OFF&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;. Spinal cord stimulation activation significantly attenuated clinical pain intensity (from 66 ± 18 to 27 ± 31, P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). In the nonpainful leg, SCS activation failed to produce an effect on TS (24 ± 20 vs 21 ± 24 in SCS &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;OFF&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; and &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;ON&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;, respectively; P = 0.277). In contrast, a significant decrease in the magnitude of TS in the affected leg was observed in response to SCS activation (from 32 ± 33 to 19 ± 24; P = 0.017). These results suggest that attenuation of TS, which likely represents suppression of hyperexcitability in spinal cord neurons, is a possible mechanism underlying SCS analgesia in patients with neuropathic pain.

Current Pain and Headache Reports, 2014

Pharmacotherapy, the main treatment option for neuropathic pain, remains a major clinical challen... more Pharmacotherapy, the main treatment option for neuropathic pain, remains a major clinical challenge. The most commonly studied drug classes in the context of neuropathic pain-antidepressants, anticonvulsants, and opioidshave only limited efficacy and frequent dose-limiting adverse effects. Yet, most guidelines recommend monotherapy as the first line of neuropathic pain treatment. Recent understanding of neuropathic pain pathophysiology suggests that multiple mechanisms, both at the peripheral and the central nervous system levels, underlie neuropathic pain, pointing to the possibility that targeting multiple mechanisms simultaneously can improve treatment outcome. A few clinical trials using various drug combinations for neuropathic pain have already been published but yielded inconsistent results, partially due to methodological problems associated with the conduction of such trials. Nonetheless, combination therapy remains an intriguing treatment option for neuropathic pain, awaiting future high-quality validating trials.

Journal of Pain and Symptom Management, 2015

Although opioid-induced hyperalgesia (OIH) is mentioned as a potential cause of opioid dose escal... more Although opioid-induced hyperalgesia (OIH) is mentioned as a potential cause of opioid dose escalation without adequate analgesia, true evidence in support of this notion is relatively limited. Most studies conducted in the context of acute and experimental pain, which seemingly demonstrated evidence for OIH, actually might have measured other phenomena such as acute opioid withdrawal or tolerance. OIH studies in patients with chronic pain have used various experimental pain models (such as cold pain tolerance or heat pain intensity). Therefore, the fact that they have yielded inconsistent results is hard to interpret. Thus far, with the exception of a few clinical case reports on OIH in patients with cancer pain and one prospective study in patients with chronic neuropathic pain, evidence for OIH in patients with chronic or cancer-related pain is lacking. Whether experimental pain models are necessary for establishing the clinical diagnosis of OIH, and which specific model is preferred, are yet to be determined. J Pain Symptom Manage 2015;49:632e636.

PAIN, 2013

Opioid analgesia is mediated primarily by modulating (inhibiting and enhancing) pain mechanisms a... more Opioid analgesia is mediated primarily by modulating (inhibiting and enhancing) pain mechanisms at the spinal and supraspinal levels. Advanced psychophysical paradigms of temporal summation (TS) and conditioned pain modulation (CPM) likely represent pain mechanisms at both levels. Therefore, the study of opioid effects on TS and CPM can shed light on their analgesic mechanisms in humans. The current randomized, double-blind study tested the effects of oxycodone on the magnitude of both TS and CPM in 40 healthy subjects. TS was tested by measuring increments in pain intensity in response to 10 repetitive painful phasic heat stimuli. CPM was assessed by subtracting the response to a painful phasic heat stimulus administrated simultaneously with a conditioning cold pain stimulus from a painful phasic heat stimulus alone. These paradigms were tested before and at 60, 120, and 180 minutes after administration of a single oral dose of either oxycodone or an active placebo. Repeated-measures analysis of variance revealed significant effects of oxycodone, but not placebo, on the magnitude of TS (F=7.196, P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;.001). Pairwise comparisons revealed that relative to baseline, TS was significantly reduced at 60 minutes (P=.008) and at 180 minutes (P=.017) after oxycodone administration. In contrast, no significant effects of either oxycodone (F=0.871, P=.458) or placebo (F=2.086, P=.106) on the magnitude of CPM were found. These results suggest that under the current experimental conditions, oxycodone exerted spinal, rather than supraspinal, analgesic effects. Furthermore, compared with CPM, TS seems more suitable for studying the mechanisms of opioid analgesia in humans.