10th World Congress on Pain, List of topics

LOW BACK PAIN, SOMATIC DYSFUNCTION AND SEGMENTAL BMD T-SCORE VARIATION
K. Snider, B. Degenhardt1 E. Johnson, J.>OMM, Kirksville College of Osteopathic Medicine, Kirksville, MO

AIM OF INVESTIGATION Somatic dysfunction (SD) results in altered vertebral biomechanics. Bone mineral density (BMD) in vertebral segments changes with altered mechanics to allow for maximum strength along lines of gravitational force. If persons with chronic low back pain (CLBP) have more SD, they may have more segmental BMD variability than those without. This study investigated the association of SD and BMD T-score variability in subjects with and without CLBP.

METHODS Sixty-four volunteers, ages 20-40, were evaluated for the following aspects of SD from L1 to L4: tissue texture changes, static rotational asymmetry, resistance to anterior springing motion, and tenderness. Severity was rated according to severe, mild to moderate, and no dysfunction. Two examiners evaluated each subject independently and then reached a consensus. Following, each subject received a DEXA scan to assess L1 to L4 BMD T-scores.

RESULTS Mean BMD T-scores for participants with CLBP were higher than for those without LBP (p<0.0001). Those participants with CLBP had more positive somatic dysfunctions findings (p<0.0001). The total number of positive findings was correlated with an increased T-score (p=0.009). Severity of static rotational asymmetry was positively correlated with the segmental T-scores (p=0.004). Severity of motion restriction was also positively related to BMD (p=0.03).

DISCUSSION Volunteers with CLBP had both higher mean BMD T-scores and more somatic dysfunction than those without CLBP. In both groups, those lumbar segments that demonstrated severe rotational asymmetry demonstrated higher BMD T-scores. Since altered position corresponds to altered weight-bearing mechanics, the increased bone may represent the altered bony metabolism that leads to arthritis.

SOMATOSENSORY PERCEPTION IN PATIENTS SUFFERING FROM LONG-TERM TRAPEZIUS MYALGIA AT THE MOST PAINFUL SITE AND IN AN AREA OF PAIN REFERRAL
A. Leffler1< E. Hansson, P.>Karolinska Institutet/Hospital, Section of Clinical Pain Research, 171 76 Stockholm, Sweden

Aim of Investigation: To examine somatosensory processing in patients with remitting trapezius myalgia and with ongoing pain in the most affected trapezius muscle for the last 3 months, in conjunction with ongoing or recurrent referral of pain to the ipsilateral arm.

Methods: Ten patients with trapezius myalgia and ten age- and sex-matched healthy controls participated. Perception thresholds to pressure pain, light touch and noxious as well as non-noxious warm and cold stimuli were assessed at the most painful site in the trapezius muscle and in an area of pain referral in the ipsilateral arm as well as in the corresponding contralateral areas.

Results: A tendency to pressure allodynia was demonstrated in the most affected trapezius muscle and contralaterally compared to controls, whereas the sensitivity to other modalities was unaltered at these sites. In the area of pain referral there was a significantly increased pressure pain sensitivity compared to contralaterally (p<0.01) as well as to the corresponding area in controls (p<0.009), in conjunction with a bilaterally decreased sensitivity to light touch in patients compared to controls (p<0.01). No differences were found in the outcome of thermal testings.

Conclusions: These findings suggest altered central processing of somatosensory input from the area of referred pain. Central mechanisms related to central sensitisation may explain referral of pain and allodynia to pressure. The decrease in light touch sensitivity in the area of referred pain and contralaterally indicated net activation of endogenous inhibitory mechanisms acting bilaterally.

ACUTE WHIPLASH - A PROSPECTIVE RANDOMIZED TRIAL IN FOUR DANISH COUNTIES. DESCRIPTIVE DATA.
A. Kongsted, H. Kasch, T. Bendix, T. Jensen, F. Back1 The Back Research Center, Funen Hospital, Ringe, Denmark , 2 Danish Pain Research Center, University Hospital, Aarhus, Denmark

Aim of Investigation: To compare the effect of three different treatment approaches initiated within one week following a whiplash injury.

Furthermore to identify risk factors for developing handicap following a whiplash injury.

Methods: Individuals presenting to an emergency department between May 1, 2001 and October 31, 2002 following a rear-end or frontal motor vehicle collision are considered for inclusion. Emergency departments in four Danish counties, covering a population of 1.8 mill. inhabitants, are involved.

Participants are randomized to one of three intervention groups. 1)stiff neck collar for a two-weeks period followed by exercise therapy, 2) early mobilization 3) advice to act-as-usual.

Clinical examinations and pressure algometry are performed within one week and at 3 and 12 months.

Questionnaires including SF-36, Illness Perception Questionnaire, Copenhagen Neck Disability Scale and VAS are completed at baseline and at 3, 6 and 12 months.

Subgroups undergo MRI, SPECT-scan, eye movement measurements and neuropsychologic testing.

Results: Descriptive data regarding the study population will be presented including demographic data, data on symptoms, disability and work capability. Status at 3-months follow-up willl be presented in about 250 cases and 1-year status in about 50.

Treatment effects are because of blinding not available at present.

Conclusions: On January 1, 2002 234 participants had been included. It is too early to present any firm conclusions.

Acknowledgments: Funded by Danish Insurance Association and The Danish

Foundation for the Advancement of Chiropractic Research and Postgraduate Education.

DEVELOPMENT OF NECK-SHOULDER PAIN AMONG FEMALE WORKERS IN POULTRY AND FISH INDUSTRY. A 6 MONTH PROSPECTIVE STUDY
P. Madeleine, M. Voigt, L. Arendt-Nielsen Center for Sensory-Motor Interaction, Aalborg University, Aalborg, Denmark , 2 Dept. of Occupational Medicine, Aalborg Hospital, Aalborg, Denmark

Aim of investigation: To investigate prospectively possible changes in sensory manifestations and motor performance during low load repetitive work task simulation in newly employed fish/poultry industry workers.

Methods: 12 female filetering employees without any sign of neck-shoulder tenderness/pain took part in the recording sessions planed within one month of employment and after six months of employment. Sensory-motor aspects were assessed by measuring: pressure pain threshold, work task timing, cutting forces, surface electromyography (EMG), and arm and trunk 3D movements during low load repetitive work simulation.

Results: After six months of employment, six workers out of twelve had developed pain and/or tenderness in the neck-shoulder region. Effects due to employment duration were observed in both groups: decreased sensibility to pressure and work cycle duration, increased arm starting position and decreased arm and trunk range of motion (P<0.05). Among the workers with neck-shoulder complaints, increased sensibility to pressure, lower force level, higher EMG activity, decreased arm movement amplitude and increased trunk posture and movement amplitude were observed compared with workers without complaints (P<0.05).

Conclusions: This study confirmed a high prevalence of neck shoulder complaints. Sensory manifestations and motor control strategy changes after six months work are of importance as they underlined a learning process as employment duration increased. The sensory-motor changes observed among workers with neck-shoulder complaints highlighted the potential physical risk factors associated with low load repetitive work.

BUPRENORPHINE TDS:COMPARISON WITH SUBLINGUAL BUPRENORPHINE IN OSTEOARTHRITIC PAIN
S.J. Ashcroft< A.J. Dietrich,L. O Brien, C.M. Napp Pharmaceuticals, Cambridge, United Kingdom

Aim To compare the efficacy and tolerability of a buprenorphine transdermal system (BTDS) with sublingual buprenorphine in osteoarthritis (OA) patients with pain in their hip(s) and/or knee(s) and to establish equivalence of the two products.

Methods This was a randomised, double-blind, parallel group study. Patients received BTDS (5 mcg/h, 10 mcg/h, and 20 mcg/h seven-day TDS) or sublingual buprenorphine (200 mcg 6 or 8-hourly and 400 mcg tablets 8-hourly) and entered a titration lasting up to 21 days. Patients achieving optimum pain control then entered the 28-day assessment period. The main outcome measures were pain intensity (primary outcome), sleep disturbance, and safety assessments.

Results Two hundred and forty six patients were enrolled; 238 were randomised to treatment (118 with BTDS and 120 with sublingual buprenorphine). One hundred and ten patients completed the study. Patients BS-11 pain scores decreased in both treatment groups. The estimated mean treatment differences for BTDS sublingual buprenorphine, (95% confidence intervals) during the assessment period for the per protocol population were 0.00 (-0.68, 0.69), -0.11 (-0.85,0.63), and -0.13 (-0.95,0.68) for the morning, midday, and evening scores, respectively. All the confidence intervals were within the pre-specified limits for equivalence (-1.5, 1.5). Use of escape medication was low. In both treatment groups, sleep disturbance caused by pain decreased between entry and assessment. The discontinuation rate was 52% for BTDS and 55% for sublingual buprenorphine. The incidence of nausea, dizziness and vomiting for BTDS was 37%, 27% and 18% respectively and for sublingual buprenorphine it was 51%, 41% and 29%.

Conclusion In the context of this study, BTDS appears to be an alternative to sublingual buprenorphine.

ANALGESIC USE, PAIN EXPERIENCE, AND HEALTH-RELATED QUALITY OF LIFE IN PATIENTS WITH OSTEOARTHRITIS OF THE HIP AND/OR KNEE PRESCRIBED ORAL OPIOID ANALGESICS
G. Morrissey-Harding, D. Ollendorf1, E. Dukes, E. Richardson1, G. Oster1 PAI, Brookline, MA , Health Economics Research, Purdue Pharma, L.P., Stamford, CT

Aim of Investigation: To characterize analgesic use, pain experience, and health-related quality of life in patients with osteoarthritis of the hip and/or knee who have been prescribed oral opioid analgesics.

Methods: Subjects had osteoarthritis of the hip and/or knee taking oral opioid analgesics; recruited from the offices of a random sample of US internists and family practitioners. Data were collected via mail survey. Measures included dosage, frequency, and duration of use of oral opioids and other analgesics, pain intensity and interference with activities,satisfaction with pain medication, and health-related quality of life, assessed on a standard 100 point scale.

Results: A total of 229 patients returned completed surveys. Subjects reported moderate to severe levels of pain and interference with activities, and low levels of health-related quality of life. Thirty-one percent reported not currently using opioids; among remaining patients, only 9% of patients reported using a long-acting opioid. Use of over-the-counter (OTC) pain relievers was widespread. One-third of those who reported using an OTC containing acetaminophen (APAP) also took prescription products containing APAP.

Conclusions: Many patients with osteoarthritis of the hip and/or knee who have been prescribed opioid analgesics nonetheless report significant pain, activity interference, and impaired quality of life. The findings suggest that the prescribing of an opioid analgesic is not a final step in pain management; continued medical management is needed to ensure acceptable health outcomes.

Acknowledgements: Research supported by Purdue, Pharma, L.P.

CATASTROPHIZING MEDIATES ELEVATED PAIN AFFECT RATINGS AMONG KNEE OSTEOARTHRITIS (OA) PATIENTS DURING SUPRATHRESHOLD PRESSURE STIMULATION
J. DeBerry1< and Pain on Group Working Fetzer T. McKendree-Smith, N. Cianfrini, L. McLain, D. Rumble, M. Blake, R. Alarcon, G. Bradley, Kersh, B.> Rheumatology, University of Alabama at Birmingham, Birmingham, AL

Aim: Compare responses of patients with knee OA and healthy controls (HC) to pressure stimulation of left (L) and right (R) knees and assess influence of coping strategy usage on McGill Pain Questionnaire (MPQ) ratings of suprathreshold stimulation levels. Methods: 11 patients (1M, 10W) with radiographic and clinical evidence of knee OA and 9 HC (2M, 7W) completed: 1) demographic and clinical symptom interview; 2) pain threshold (PT) procedure (ascending method of limits) at 6 sites on L and R knees, and 3) MPQ and Coping Strategy Questionnaire (CSQ) following 5-minute, suprathreshold (2-3 kg>PT) stimulation of L and R knees. Mean group differences on PT, MPQ sensory and affect scales, and CSQ Catastrophizing scale were analyzed by 2-tailed t-test. Influence of Catastrophizing on group difference in pain affect assessed by ANCOVA. Results: Patients did not differ from HC in age and education level or MPQ sensory ratings. However, patients, compared to HC, produced lower PT as well as higher MPQ pain affect ratings and Catastrophizing scores during suprathreshold stimulation of both knees (P's<.05). Controlling for Castrophizing by ANCOVA eliminated group difference on pain affect. Conclusions: Patients' lower PT are probably due to high nociceptive input produced by stimulation of large, deranged joint. However, patients' high pain affect ratings are mediated by high use of catastrophizing as well as nociceptive input. OA patients with high pain affect levels may benefit from cognitive-behavioral pain management training as an adjunct to standard care.

TEMPOROMANDIBULAR JOINT PAIN AND DYSFUNCTION IN ADULT WITH RHEUMATOID ARTHRITIS: AN EPIDEMIOLOGICAL SURVEY
U. Capurso, A. Russo, L. Vecchiet, I. Marini Dpt. of Oral Surgery, School of Dentistry, University of Bologna, Bologna, Italy , 2 Dpt. of Medicine and Ageing, University of Chieti, Chieti, Italy

Aim of investigation: To evaluate pain and signs of temporomandibular joint (TMJ) dysfunction in patients (pts) with rheumatoid arthritis (RA+).

Methods: This study included 93 randomly selected pts RA+ (71F-22M; age range: 26-75yrs) and 61 healthy subjects as controls (40F-21M; mean age: 52.1yrs). Each subject was evaluated for both pain thresholds and stomatognatic functions. The intensity of pain was measured by the Visual Analogue Scale (VAS), whereas the anamnestic dysfunction index of Helkimo was used to assess stomatognathic dysfunctions. Radiographic examinations were performed through orthopantomographic machine.

Results: Pts RA+ showed low prevalence of pain symptoms (only 30%). Where occurred, pain was localized in both the sides of TMJ, with an intermittent pattern and a VAS score of 7.1. Common clinical findings were crepitus from TMJ (not significant), impaired mandibular mobility (p<0.001), tenderness during both joint and masticatory muscles palpation (p<0.01). A complete joint locking was found in 6% of pts. Radiographic examination showed, in almost all the pts, extreme resorptin and remodeling of the condyle, as well as increase in joint space and erosion of the fossa, otherwise reduced joint space and sclerosis.

Conclusions: RA is a particular disease involving several joints, also TMJ. Both symptoms and systemic involvement are minimal in the affected pts, whereas articular damage may occur quite early. This survey has also shown a functional involvement of masticatory system in pts RA+ (p<0.001), even if spontaneous joint pain was not frequent. More careful diagnostic and therapeutic approaches are necessary.

KNEE OSTEOARTHRITIS (OA) IS ASSOCIATED WITH ALTERED CENTRAL PROCESSING OF PRESSURE STIMULATION OF AFFECTED AND DISTAL SITES
B.C. Kersh, L.A. Bradley, G.S. Alarcn1, D.A. McLain, T. Powell, M. Rumble, B. Corbitt, Working Group on Pain and Suffering Rheumatology, University of Alabama at Birmingham, Birmingham, AL , 2 Fetzer Institute, Kalamazoo, MI

Aim of Investigation: Examine verbal and physiological responses to pressure stimulation of left and right (L,R) knees and distal (arm, shoulder) sites in OA patients and healthy controls (HC).

Methods: 10 knee OA patients (9W,1M) and 10 HC (7W,3M) administered: 1)pressure pain threshold (PT) assessment of 6 L,R knee sites; 2)sensory decision theory (SDT) assessment of L,R distal sites; 3)SPECT imaging of brain regional cerebral blood flow (rCBF) during sensory control (SC; 1kg) and suprathreshold (ST; 3kg>PT) stimulation of L,R knee sites; and 4)McGill Pain Questionnaire (MPQ) assessment of ST stimulation.

Results: Patients did not differ from HC in MPQ sensory ratings. However, patients, compared to HC, produced: 1)lower knee PT; 2)higher SDT discrimination ability at distal sites; and 3)higher MPQ pain affect ratings at knee sites (all P's<.05). During ST stimulation of L,R knee sites, both patients and HC displayed increased rCBF in contralateral somatosensory cortex, whereas only patients displayed increased rCBF in bilateral cingulate cortex (all P's<.05).

Conclusions: 1)PT and SDT results suggest pressure stimulation of knee and distal sites produces greater nociceptive input in knee OA patients compared to HC; 2)Patients' higher pain affect ratings during ST stimulation probably due to greater nociceptive input and activation of brain structures involved in processing pain affect; 3)Knee OA is associated with altered central processing of pressure stimulation at affected and distal sites.

Acknowledgments: Supported by grant from Fetzer Institute.

A PILOT PROSPECTIVE LONGITUDINAL STUDY OF MOTOR DYSFUNCTION FOLLOWING WHIPLASH INJURY
M. Sterling1< R. Vicenzino, B. Jull, G.>Physiotherapy, The University of Queensland, Brisbane, QLD, Australia

AIM OF INVESTIGATION To investigate prospectively the development of whiplash induced changes in motor function.

METHODS 47 subjects with acute whiplash associated disorders (WAD) grade I to III were followed from within 4 weeks of injury to 2 and 3 months post injury. 20 asymptomatic subjects were also monitored. Motor function was measured by active range of motion (ROM), joint position error (JPE) and superficial neck flexor muscle activity (surface EMG) during a low-load cranio-cervical flexion movement. Fear of re-injury (TAMPA) was also measured.The WAD subjects were classified at 3 months post injury using the Neck Disability Index into: recovered (< 8), mild pain and disability (10-28) or moderate/severe pain and disability (>30). A mixed model MANCOVA with a between subjects factor of Group (4 levels: asymptomatic, recovered, mild, moderate/severe) and a within subjects factor of Time with a covariate for fear of re-injury (Tampa) was used for data analysis (p<0.05).

RESULTS Preliminary analysis shows that the group classified as moderate/severe WAD demonstrated decreased ROM, increased EMG activity (superficial neck flexors) and JPE at all time frames. This appeared to be independent of the fear of re-injury. Although the recovered and mild groups demonstrated some changes in motor function (mainly ROM) these were less substantial than the moderate/severe group.

CONCLUSIONS: WAD patients reporting persistent moderate/severe symptoms demonstrate changes in motor system function occurring soon after injury and persisting to 3 months. This may have implications for the selection and timing of rehabilitation strategies in the management of WAD.

ACKNOWLEDGMENTS This study was supported by a grant from Suncorp Metway Insurance.

EFFECT OF LOCAL INJECTION OF 10% XYLOCAINE ON PAINFUL STEOARTHRITIS OF THE KNEE JOINT.
M. Kawasaki1< Y. Toshikazu, T. Takahiro, U.>Orthopaedic Surgery, Kochi Medical School, Nankoku, Japan

Aim of Investigation: Neurotoxicity of high-dose xylocaine has been reported previously. However, clinical use of high-dose xylocaine for painful degenerative disease is not investigated. The aim of this study was to investigate whether local injection of high-dose xylocaine could attenuate tenderness and motion pain existing in chronic osteoarthritis of the knee joint.

Methods: Fourteen patients, who had tenderness and pain during joint movement at the medial side of degenerative femorotibial joint for more than 6 months, were examined in this study. The knee pain during movement was assessed by visual analog scale (VAS) score and pressure pain thresholds for tenderness at the site of the injection were evaluated by means of a hand-held pressure algometer (Hoggan Health Industries, Inc.). As for the treatment, 1 ml of 10% or 1% xylocaine was injected into the periarticular tissue of the most painful tenderness point at the medial femorotibial joint. These pain intensities were measured before (controls), and 2 weeks and 4 weeks after the injection.

Results: Decreased VAS score (p<0.05) and increased pressure pain thresholds (p<0.05) were observed 2 weeks after the injection of 10% xylocaine, compared with controls respectively. On the other hand, there were no significant differences between before and after the injection of 1% xylocaine.

Conclusions: These results suggest that the injection of 10% xylocaine may produce more effective and long-term analgesia for pain following osteoarthritis of the knee, compared with the injection of 1% xylocaine.

CHARACTERICTICS OF PAIN IN A NEW INFLAMMATORY MYOPATHY: MACROPHAGIC MYOFASCIITIS
M. Melse, X. Marsiglia, P. Chrin2, E. Collin Consultation de la Douleur, Hpital Piti-Salptrire, Paris, France , 2 Dpartement de Mdecine Interne, Hpital Piti-Salptrire, Paris, France

Aim of investigation : Macrophagic myofasciitis (MMF), a new type of inflammatory myopathy of unknown cause first described in 1993, shows an increasing incidence. MMF is characterized by muscle infiltration by granular periodic acid-Schiffs reagent-positive macrophages and lymphocytes. Macrophages with inclusions of aluminium hydroxyde, a common vaccine adjuvant, are constantly detected. Clinical symptoms include diffuse pain, marked asthenia, muscular weakness and fever.

The present study investigated the characteristics of pain in patients with diagnostic of MMF in search of improving pain treatment.

METHODS Between April and December 2001, all patients from the Internal Medecine Departement of Piti-Salptrire University Hospital meeting diagnostic criteria for MMF were referred to the pain team of the hospital. Pain assessment included localization (body chart), intensity (EVA), qualitative charactericstics (QDSA) and mood disturbance (HAD scale).

RESULTS Thirty seven patients (twenty four women, thirteen men; mean age 41.3 years) were included. Pain symptoms included myalgia (98%) and arthralgia (44%). The mean intensity of pain was 47 mm in resting condition and 75 mm during activity. The major localizations were arms, legs and proximal articulations. Anxiety was the major mood disorder associated with pain (28 %). None of the classical pain treatments were efficient.

CONCLUSION This study shows that patients with this emerging (new) inflammatory myopathy (MMF) suffer from severe activity-associated pain that resists, at least partly, to classical treaments (analgesics, anticonvulsivants, antidepressants).

NEUROPEPTIDE-IMMUNOREACTIVE NERVE FIBERS IN PAINFUL AND NON-PAINFUL MUSCULAR DISORDERS: AN IMMUNOHISTOCHEMICAL STUDY ON HUMAN MUSCLE BIOPSIES
A. George1< C. Schneider,> Department of Neurology, University Wuerzburg, Wuerzburg, Germany

AIM OF INVESTIGATION: To determine whether the neuropeptide-expression pattern of free nerve fibers and inflammatory processes in their vicinity are relevant for the development of myopathic pain in humans.

METHODS: Fiftytwo patients (24 female, 28 male; mean age 4715) undergoing a muscle biopsy were prospectively studied for muscular pain by verbal assessment including VAS, the McGill Pain questionnaire and a depression score and by pressure-pain-threshold measurement (PPT) using a muscle algometer. Muscle biopsy specimens were analysed with standard methods. The perivascular, endo- and epimysial area immunoreactive (IR) for CD68, Leu4, EvG, CGRP, substance P (SP), nerve growth factor and PGP9.5 was determined morphometrically on cryosections.

RESULTS: Muscular pain was observed in 30/52 patients (58%), muscle tenderness and myaesthesia in 24% and 44%, respectively. Many patients could distinguish between two to ten different pains of varying site and nature: persistent (29 %), intermittent (58%), exercise-related (48%), temperature-dependent (30%). PPT was reduced in 21%. CGRP- and SP-IR was increased in inflammatory muscle disorders which were mostly painful. In non-inflammatory painful myopathies this increase could not almost be observed. Perivascularly, no significant difference for CD68-positive cells was found.

CONCLUSIONS: Clinical data on frequency and character of muscle pain in neuromuscular disorders suggest different underlying peripheral and central mechanisms. Immunohistochemical data suggest that a change in neuropeptide-IR nerve fibers may contribute to the development of myopathic pain in inflammatory settings.

THE ANALGESIC EFFECT OF MORPHINE, LIDOCAINE AND KETAMINE IN WHIPLASH ASSOCIATED DISORDER PATIENTS WITH DIFFERENT PAIN DURATION.
D. Lemming1, rensen, T. Graven-Nielsen, L. Arendt-Nielsen, B. Gerdle, Pain and Rehabilitation Center, Linkping University Hospital, Linköping, Sweden , 2 Division of Rehabilitation Medicine, Department of Neuroscience and Locomotion, Linkping Health University, Linköping, Sweden , 3 Center for Sensory-Motor Interaction, Laboratory for Experimental Pain Research, Aalborg University, Aalborg, Denmark

Aim of investigation: To evaluate the analgesic response to intravenous administration of morphine (MORP), lidocaine (LID) and ketamine (KET) in relation to duration of chronic pain after whiplash trauma.

Methods: Thirtythree patients with whiplash associated disorder grade 2 or 3, according to the Quebec classification, were included. Clinical examination and case history had established diagnoses. The pharmacological evaluation was performed in a randomized, double-blind, cross-over study design and consisted of a 30 min period of i.v. administration of MORP (0.3mg/kg), LID (5mg/kg), KET (0.3mg/kg) or isotonic saline (placebo). Pain intensity ratings on a visual analogue scale were taken before, during and after the infusion. The patients were classified as placebo-responders, non-responders or specific responders (minimum 50% decrease of VAS scores) to the drugs. Responders were divided in 2 groups with different pain duration: 0-2 and longer than 2 years.

Results: Thirty patients completed the study, 2 were placebo-responders and 10 non-responders. Out of 18 responders there were 15 MORP responders, 11 LID responders and 14 KET responders. In patients with WAD less than 2 years, 7 responded to MORP, 5 to LID and 8 to KET. Patients with pain duration longer than 2 years, 8 responded to MORP, 6 to LID and 6 to KET.

Conclusions: We found no significant correlation between pain duration and profile of responders.

MECHANICAL ALLODYNIA BUT DECREASED SENSATION IN PATIENTS WITH CHRONIC ARTHROPATHIES
A.J. Hendiani1, K.N. Westlund1, N. Lawand1, N. Goel1, J. Lisse2, T. McNearney1</SUP< TD> 1 Anat & Neurosci, Univ of TX Med Br, Galveston, TX , 2 Int Med, Univ of Arizona, Tucson, AZ

Aim of Investigation: To measure cutaneous mechanical sensation and pain thresholds overlying joints of arthritic patients.

Methods: Patients with rheumatoid arthritis (RA; N=27) and osteoarthritis (OA; N=28), were compared with those of age- and weight-matched normal subjects (N=27). Sensation and pain thresholds were mapped using von Frey fibers in a 10cm radius grid about the patella. Subjective pain and inflammatory parameters were assessed by VAS, cutaneous temperature and circumference for each knee. Intra- and inter-subject data were analyzed by paired t-test and ANOVA.

Results: Compared to normals, RA and OA patients had (1) significantly higher VAS pain scores, joint circumferences and (for RA only) surface temp,(2) significantly higher thresholds for mechanical sensation (0.0140.003 vs 0.1020.045 and 0.1840.031 grams, for control vs. RA and OA respectively), and (3) decreased thresholds for painful stimuli indicative of mechanical allodynia (446.683 0 vs 272.6640.01 ,353.134.52 grams, for normal vs. RA and OA respectively). The extent of changes for these thresholds was correlated in the same regions. In RA patients, correlations were significant for skin temp and mechanical allodynia.

Conclusions: Patients with symptomatic arthropathies have increased thresholds for sensation but decreased pain thresholds not attributable to medications. Strict correlation of extent of changes in mechanical sensitivity and allodynia may reflect convergent phenomena affecting both peripheral receptors and dorsal horn neurons that can contribute to the abnormal cutaneous sensation associated with arthritic joints.

Acknowledgements: This study was supported by NIH NS11255 and NS32778.

POSTOPERATIVE BUNIONECTOMY PAIN AND ANALGESIC DRUGS: MODEL CHARACTERISTICS
A.A. Jackson1< S.T. Golf, M.H. Baum, D.R. Black, P. Daniels, S.E. Desjardins, P.J.> Clinical Site Operations Analgesia and Psychiatry Research, SCIREX Corporation, Austin, TX

Aim of Investigation: To describe the model characteristics of the bunionectomy acute pain model when analgesic drug dosing occurs on the first post-operative day.

Methods: A double blind, randomized, parallel design study was conducted in 125 patients undergoing first metatarsal bunionectomy (with osteotomy) under regional anesthesia and propofol sedation. Patients were administered repeated doses of local anesthetics for the remainder of the surgical day. On the morning of the next day, when patients experienced moderate or severe pain (VAS > 40 mm), patients were administered a single dose of either placebo, rofecoxib 50 mg, acetaminophen 1000 mg + Oxycodone 10 mg. Pain intensity and relief were measured at specified intervals over the next 8 hours. Rescue medication use was assessed as well as patient global evaluation at the end of 8 hours or at the time of rescue. Onset was measured using a two stopwatch method.

Results: This paper will summarize the patient, surgical and anesthetic characteristics of this acute pain model. Both active treatments (Rofecoxib and Tylox) separated from placebo (p<.05) for total effect (TOTPAR-8), peak effect, duration of effect and patient global evaluation.

Conclusions: This bunionectomy acute pain model appears to provide a robust and practical model with excellent assay sensitivity. These patients medicate for at least 5 days postoperatively and this appears to provide a useful single dose and multiple dose model for evaluation of new analgesics.

Acknowledgments: All authors are employees or consultants of Scirex Corporation. No financial support from any sponsor was received to support this study.

10th World Congress on Pain, List of topics

10th World Congress on Pain. International Association for the Study of Pain, San Diego, California, USA August 17-22, 2002