10th World Congress on Pain, List of topics

THE EVALUATION OF CLINICAL EFFECTIVENESS OF EAST-WEST MEDICAL MANAGEMENT FOR THE CENTRAL POSTSTROKE PAIN
D. Lee1 D. Kim, K. East-West Pain Clinic, Kyung Hee University Medical Center, Seoul, South Korea

Aim of Investigation: Central poststroke pain (CPSP) can occur as a result of lesion or dysfunction of the brain from stroke and may cause many difficulties in the social activities and daily life. In this study, we evaluate the clinical effectiveness of east-west medical management for CPSP through VAS (Visual Analogue Scale), infrared thermography, MBI (Modified Barthel Index) and Rankin scale.

Methods: We treated thirty patients with oriental (eastern) medical treatment and western & oriental medical (combined) treatment. Each group has fifteen patients of the CPSP. We evaluated their pain through VAS pain score, the skin temperature of pain site by infrared thermography and assessed their mobility & rehabilitation ability through MBI, Rankin scale before and after pain treatment.

Results: The skin temperature of pain site was lower than non-pain site. The difference of skin temperature improved from 0.65C to 0.39C after oriental treatment and 0.68C to 0.27C after combined treatment. VAS scores improved from 7.9 to 4.7 after oriental treatment and 8.1 to 4.6 after combined treatment. MBI scores improved from 61.40 to 85.00 after oriental treatment and 52.26 to 77.13 after combined treatment.

Conclusions: The difference of skin temperature and Rankin scale scores more significantly improved after western & oriental medical treatment than oriental medical treatment. According to the results, we thought east-west medical management is very useful treatment for CPSP and rehabilitation of the patients with stroke.

REDUCED HEAT PAIN THRESHOLDS IN PARKINSON'S DISEASE
A. Shifrin, R. Djaldetti, E. Sprecher¹, E. Melamed, D. Yarnitsky Neurology, Rambam Medical Center, Haifa, Israel , ² Neurology, Rabin Medical Center, Petah-Tiqva, Israel

Aim of investigation: To assess pain perception in patients with parkinson's disease, in an attempt to understand the pain phenomena in this disease.

Methods: Pain psychophysics were performed on two arms by measuring contact heat pain thresholds. Disease severity was assessed by UPDRS, and mean endogenous ongoing pain was estimated on VAS.

Results: 22 hemiparkinsonian patients (age 60.0+-11) and 27 age matched controls (58.4+-6.3) were studied. 17 patients reported spontaneous pain of various distributions. Mean heat pain threshold (both sides) was 42.9+-0.65 degree C for patients, and 46.1+-0.62 for controls (p=0.0008, t-test). Within patients, thresholds in the more affected parkinsonian side were lower than the other side (42.12+-0.41 vs.43.6+-0.41, p=0.012). Disease duration and presence or absence of spontaneous pain did not correlate with pain tresholds. Correlation between delta heat pain (side to side) and delta UPDRS tended to be correlated, with r=0.42, p=0.08.

Conclusions: Pain system seems to be sensitized in parkinson's disease, mainly in the affected hemiparkinsonian side. This can underlie the frequent unexplained complaints of pain in these patients.

NEURONAL HYPEREXCITABILITY: POSSIBLE INVOLVEMENT IN SPINAL CORD INJURY PAIN
N.B. Finnerup, A. Fuglsang-Frederiksen, C. Gyldensted4, F.W. Bach, T.S. Jensen Danish Pain Research Center, Aarhus University Hospital, Aarhus, Denmark , ² Department of Rhematology, Viborg Hospital, Viborg, Denmark , ³ Department of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark , ⁴ Department of Neuroradiology, Aarhus University Hospital, Aarhus, Denmark

Aim of investigation: To determine the degree of sensory hypersensitivity in spinal cord injury (SCI) patients with and without central neuropathic pain.

Methods: 20 SCI patients with central neuropathic pain and 20 SCI patients without pain were studied for brush and cold evoked pain, pinprick hyperalgesia, and pain to repetitive pinprick stimuli. Extent of SCI was confirmed by quantitative sensory testing, recording of somatosensory evoked potentials, and magnetic resonance imaging.

Results: More SCI pain patients than pain free patients had brush or cold evoked pain or dysesthesia (p < 0.00). Intensities of evoked sensations to brush and pinprick at level were significantly higher in patients with pain than in patients without pain, whereas there was no difference in evoked pain intensity to repetitive pinprick stimuli. Intensities of evoked sensations to brush and pinprick at level were significantly correlated to intensity of spontaneous central pain below level (p < 0.00).

Conclusions: There is a significant relation between evoked pain at level and spontaneous pain below level in SCI patients. Hyperexcitability of central neurons may play a significant role in generating central pain in patients with SCI.

Acknowledgments: Supported by grants from Ludvig og Sara Elsass Foundation, Institute of Experimental Clinical Research Aarhus University, Danish Medical Research Council, Foundation for Research in Neurology, and Danish Society of Polio and Accident Victims (PTU).

EFFECTS OF SURGERY ON CENTRAL PAIN AND SENSORY DEFICITS ASSOCIATED WITH SYRINGOMYELIA: A LONG-TERM PROSPECTIVE PSYCHOPHYSICAL STUDY
N. Attal1, M. Tadi, D. Bouhassira Centre d'Evaluation et de Traitement de la Douleur, Hpital Ambroise Par, Boulogne, France , ² Service de Neurochirurgie, Hpital Kremlin-Bictre, Kremlin-Bicêtre, France

AIM OF INVESTIGATION: This prospective study evaluated the outcome of the pain and sensory deficits associated with the syringomyeliaChiari complex or post-traumatic syringomyelia after surgical decompression.

METHODS: Fifteeen consecutive patients presenting with clinical and radiological evidence of cervico-dorsal syringomyelia were evaluated before surgery, then at 6 months and 2 years. The extent of thermal deficits was measured using thermo-rollers. Quantitative sensory tests (QST) were used to measure the mechanical, vibration and thermal detection thresholds and the mechanical, thermal pain threholds. MRI was performed before and after surgery to measure the syrinx dimensions.

RESULTS: There was a significant effect of surgery on proprioceptive deficits, but not on the magnitude of thermo-algesic deficits. Pain evoked by effort/movement, but not pain at rest, was reduced at 2 years. The syrinx was collapsed in 80 % of cases and the foramen stenosis and the syrinx/canal index were improved. The evolution of pain, thermoalgesic deficits proprioceptive deficits, syrinx dimensions were not correlated. There was a significant correlation between the duration of symptoms and the effects of surgery on the magnitude of thermal deficits. Notably patients operated within less than 2 years were improved or stabilized.

CONCLUSIONS: This study shows that 1/ neuropathic pain due to syringomyelia is not correlated to thermoagesic deficits 2/ the mechanisms of pain, thermoalgesic deficits and proprioceptive deficits are distinct ; 3/ early surgical management may result in a better outcome.

TWO MECHANISMS FOR COLD ALLODYNIA IN CENTRAL PAIN
E. Sarlani, J. Greenspan OCBS Dept., Dental Sch., Univ. of MD, Baltimore, MD , ² Neurosurgery Dept., Johns Hopkins Hosp., Baltimore, MD

Aim of Investigation: One proposed mechanism for allodynia is disinhibition, where disruption of innocuous somesthetic input hampers an inhibitory process that normally attenuates nociceptive signaling to the cortex. Specifically, injury to the innocuous thermal sensory system would 1) diminish cool perception, and 2) reduce cool-mediated inhibition of cold-evoked pain, thus producing cold allodynia (A.D. Craig, Pain Forum, 7:1-14, 1998). Our study tested this model by evaluating the cold sensitivity of central pain patients.

Methods: Ten central pain patients immersed a hand in water baths ranging from 10-30C, and rated the intensities of their cold sensations and pain intensity on two VAS's.

Results: Four patients exhibited cold allodynia. Three appeared similar, in perceiving 20-25C baths as mild to moderately painful. At the same time, they reported normal cool intensity ratings to mildly cool temperatures (25-30C). The 4th subject exhibited extreme cold allodynia, perceiving even 30C as intolerably painful.

Conclusions: These results suggest two models of cold allodynia. First, "mild" allodynia, exhibited by the 3 patients, may be due to disinhibition, but this can occur independently of cool sensory pathway compromise, since these patients showed little or no cool perception deficits. Second, "extreme" cold allodynia, exhibited by the 4th patient, is not explained by disinhibition. Instead, we propose a model of central sensitization that has been ascribed to tactile allodynia. Specifically, innocuous cool input not only fails to inhibit the nociceptive system, it reverses, and is now excitatory. Thus, cold allodynia may result from two different neural mechanisms, distinguishable by severity.

Acknowledgments: Supported by NIH grants NS-39337 & NS-38493.

COLD SENSATION IN CENTRAL POST STROKE PAIN
T.S. Jensen, A.D. Kristensen, G. Andersen, K. Vestergaard Neurology & DPRC, Aarhus University Hospital, Aarhus, Denmark , ² Neurology, Aalborg Hospital, Aalborg, Denmark

Aim of Investigation: Central post stroke pain (CPSP) is a classical example of a neuropathic pain syndrome characterised by burning pain, sensory loss in body parts corresponding to brain sites that have lost sensory input by the stroke. Under normal conditions cold responding neurons may exert an inhibitory effect on pain. In this study we tested the hypothesis that reduced cold sensation play a role for the presence of pain in CPSP.

Methods: 28 patients, 12 F and 16 M,(mean age: 59.98.6 years)with MRI or CT verified stroke were examined using quantitative sensory testing for thermal and mechanical stimuli using Thermotest (Somedic) and calibrated von Frey hairs, respectively. Sensory thresholds were determined in the most painful body part and in homologue normal body parts and compared to perceived VAS pain.

Results: Pain duration was 26.218.8 months with an ongoing pain score: 6.41.9 (VAS:0-10) and evoked pain score:4.13.2. Cold detection threshold was reduced in all patients on the painful side compared to the non-painful side: 24.17.50C vs. 27.91.80C, P<0.02. Heat pain threshold was also increased on the painful side compared to the non-painful side: 44.11.20C vs. 43.64.10C. Cold pain threshold, heat detection threshold and mechanical threshold did not differ between the two sides. There was no correlation between ongoing pain and cold detection or cold pain threshold.

Conclusion: The disrupted thermal sensation in post stroke pain is not associated with a corresponding relationship between altered cold perception and ongoing pain.

Acknowledgement: Supported by grants from Danish Medical Research Council, Karen Elise Jensens Foundation.

CENTRAL POST STROKE PAIN: CLINICAL-ENCEPHALIC IMAGING CORRELATIONS
R.A. Oliveira, M.J. Teixeira1 Pain Center, So Paulo University Medical School, São Paulo, Brazil

Aim of investigations: To evaluate the symptomatic expression of the central post-stroke pain (CPSP) patients and to correlate with the encephalic lesion sites.

Methods: Forty CPSP patients were prospectively characterized according to the clinical aspects and symptomatic expression of pain and were correlated with the magnetic resonance (MR) (n=24) or computerized tomography (CT) (n=16) imaging of the encephalum. The lesion sites were classified as thalamic (8), thalamus-capsular (5), supratentorial extra-thalamic (15), brain stem (8) and undetermined (4).

Results: The strokes were ischemic in 87.5% patients and haemorragic in 12.5%. Twenty-one (52.5%) had multiple encephalic lesions. Pain installed insidiously in 77.5% of the cases, had continuous character in 85.0% and was described as burning by 71.7% of the patients. Pain was felt during the first three months after the stroke in 75.0% of the patients. Thermosensorial deficits were detected in all cases. Hyperalgesia (22.5%), hyperpathia (75.0%), thermal and or tactile and or kynestesic allodynea (75.0%) were detected. Myofascial pain syndrome (MPS) was diagnosed in 67.5% of the patients, had segmentar distribution in 57.5% and predominated in the supra-tentorial extra-thalamic lesion group (P<0.001).

Conclusions: CPSP was necessarily associated with thermosensorial deficits despite the encephalic lesion site. Multiple encephalic lesions were predominant, however CPSP also occurred in the absence of abnormalities detected by MR or CT scans. No correlation between the encephalic images and the occurrence of CPSP was found. The muscle-skeletal abnormalities must be recognized in the CPSP patients. The MPS were found in more than 2/3 of this series; this aspect has not been described yet and have straight therapeutic implications.

INTRACEREBROVENTRICULAR ADMINISTRATION OF MORPHINE FOR CONTROL OF IRREDUCIBLE CANCER PAIN
C.E. Cavalcanti Castro A. Dept of Neurosurgery/Neurology, University Hospital, Sao Luis, Brazil

AIM OF INVESTIGATION: Intracerebroventricular morphine analgesic was used for the treatment of cancer pain and administered using implanted access ports in 30 patients from 1995 to January 2001. This treatment has the advantage of effective control of pain, and was achieved in nearly all of the patients.

METHODS: Since 1995 thirty patients underwent 30 intracerebroventricular morphine analgesic procedures for the treatment of cancer pain that was refractory to other treatment.

RESULTS: Immediate relief of pain was achieved in 25 patients with another 5 patients reporting improvement. Long-term results were similar.

CONCLUSIONS: This method of intraventricular administration is invasive and must be considered only after the failure or limitation of lumbar intrathecal administration. The choice of technique used depends mainly on the site of the pain. Indications for ICV morphine administration must be limited to irreductible neoplastic pain.

AN EXPLORATION OF PAIN ASSOCIATED WITH AMPUTATION AND PROSTHETIC USE
A.S. Whyte Scottish Network for Chronic Pain Research, Univ of Stirling, Stirling, United Kingdom , ² Dept of Psychology, Glasgow Caledonian Univ, Glasgow, United Kingdom

AIM OF INVESTIGATION: To explore the extent, and types of pain experienced by long-term, lower-limb prosthetic users and to examine the impact of such pain on quality of life.

METHOD: This study utilised a semi-structured interview format containing both closed and open questions. The interviewer also invited participants to discuss additional topics participants defined as relevant that were not contained within the interview. Interviews were taped and subsequently transcribed for analysis. Tapes were then deleted. Forty-five amputees participated in this study. Mean age was 51 and 82% percent of the sample was male.

RESULTS: All participants reported ongoing phantom pain on a regular basis. Fifty three percent of the sample reported daily episodes, the remaining 47% ranging from every few days to approximately monthly. On a 100-point numerical rating scale the average level of pain was 76. Twenty-eight percent of the sample reported regular episodes of stump pain, however, the entire sample reported that the experience discomfort or pain within the stump while adjusting to a new prosthesis. Seventy-five percent of the sample reported pain in the hip and/or back that they attributed to regular prosthesis use. This pain was generally described as less intense than phantom pain; but also as more distressing because of it's incessant nature.

CONCLUSIONS: Although there has been a great deal of research on phantom limb pain, there is little looking at other types of pain experienced by this group. Future research should address the distress reported by this sample in relation to hip/back pain.

A SURVEY OF KNOWLEDGE, ATTITUDES, AND BELIEFS OF HEALTH CARE PROFESSIONALS REGARDING PHANTOM LIMB PAIN AND OTHER POST AMPUTATION PHENOMENA
C. Richardson, S. Glenn Pain Relief Foundation, University Hospital Aintree, Liverpool, United Kingdom , ² School of Health and Human Sciences, Liverpool John Moores University, Liverpool, United Kingdom

Aim Studies on the incidence of phantom limb pain (PLP)amongst amputees has shown variation between 2-80% (Jensen and Nikolajsen 1999). One suggested reason for this variation are the attitudes and beliefs of amputees, health care professionals and researchers towards phantom phenomena (Sherman 1994; Vaida & Friedman 1991). This survey was designed to identify attitudes and beliefs, of health care professionals involved in pain management, regarding PLP.

Method A questionnaire based on reported post amputation phenomena, was devised and distributed to members of The British Pain Society and local General Practitioners. Questions examined phantom sensations (e.g. kinetic, kinaesthetic and telescopic quality), PLP and its management, and stump pain.

Results 1017 questionnaires were returned (61%). Most pain management professionals see less than 10 amputees per year, which may reflect the results. Phantom sensations are ubiquitous (Hill 1999; Stannard 1993), however only one third of pain specialist doctors identified this. Similar profiles were found for PLP and stump pain. There were differences between professional groups concerning qualities of phantom phenomena and predisposing factors. Professionals not treating amputees sometimes gave more accurate answers. Antidepressants, anticonvulsants and TENS are the preferred treatments.

Conclusion The diversity found within the literature is reflected in these results. These findings could result in fragmented and sub-optimal care for some suffers of PLP. There is urgent need for a rationalisation of the teaching and treatment of PLP.

EPIDURAL ANALGESIA AND PHANTOM PAIN AFTER LEG AMPUTATIONS
W.T. Edwards, D.G. Smith, K.M. Campbell, J.M. Czerniecki, M.P. Jensen, L.R. Robinson, Anesthesiology, University of Washington, Seattle, WA , ² Rehabilitation Medicine, University of Washington, Seattle, WA , ³ Orthopedics, University of Washington, Seattle, WA

Aim of Investigation: Epidural blocks have been thought to reduce phantom pain. We undertook to determine the effect of perioperative epidural treatment on phantom pain at times up to one year after amputation.

Methods: 89 patients undergoing lower extremity amputation were studied in two groups. Group 1: 22 patients were randomized to active (bupivacaine) or placebo (normal saline) epidural. Catheters were inserted and treatment was started 1 hr before incision. This continued for 72 hours. All patients had opioid PCA. Group 2: 67 patients agreed to be studied but declined randomization. They were treated like the active patients in Group 1 if they requested epidural (31) or with just PCA if they declined epidural (36). All got general anesthesia. Pain, opioid use, complications, length of stay were measured. At 1 mo, 6 mos, and 1 yr post amputation, pain intensity and patterns, medication use, pain interference, and disability were assessed.

Results: Pain, opioid use and length of hospital stay were reduced for patients with active epidural compared to those receiving opioid alone. No differences in any variable existed among groups at any time during follow-up.

Conclusion: Epidural analgesia reduces postoperative pain, opioid consumption and length of stay in patients undergoing elective leg amputation. It offers no advantage in prevention of phantom or residual limb pain in this population.

Acknowledgements: Supported by grant PO1 HD/NS33988 Nat Inst of Child Health and Human Development and the National Institute of Neurological Disorders and Stroke

RECURRENCE OF PHANTOM PAIN IN APUTEES DECADES AFTER ORIGIONAL SURGERY
W.P. Mulloy Department Of Medicine, Thomas Jefferson University Hospital, Philadelphia, PA

AIM OF INVESTIGATION: To determine the etiology of reappearance of phantom pain in amputated extremity decades after the original surgery.

METHODS: This study was conducted among veterans of the past century. The results are based upon research of those involved, mostly survivors of Korean and Vietnam combat. When the original amputation was performed, the nerve sheath was retracted and the involved nerve was severed above the level of the sheath, which was then elongated to cover the nerve ending and give protection from surrounding tissue and possible future trauma. The current pain is due to growth of the nerve over the years and its ability to penetrate the distal extremity of the sheath. This gives rise of localized pain the area.

RESULTS: The locally appreciated pain can be alleviated by procaine or other locally administered analgesics, but it not responsive to opium derivatives which act centrally.

THE EVALUATION OF CLINICAL EFFECTIVENESS OF EAST-WEST MEDICAL MANAGEMENT FOR THE CENTRAL POSTSTROKE PAIN
D. Lee1 D. Kim, K. East-West Pain Clinic, Kyung Hee University Medical Center, Seoul, South Korea

Aim of Investigation: Central poststroke pain (CPSP) can occur as a result of lesion or dysfunction of the brain from stroke and may cause many difficulties in the social activities and daily life. In this study, we evaluate the clinical effectiveness of east-west medical management for CPSP through VAS (Visual Analogue Scale), infrared thermography, MBI (Modified Barthel Index) and Rankin scale.

Methods: We treated thirty patients with oriental (eastern) medical treatment and western & oriental medical (combined) treatment. Each group has fifteen patients of the CPSP. We evaluated their pain through VAS pain score, the skin temperature of pain site by infrared thermography and assessed their mobility & rehabilitation ability through MBI, Rankin scale before and after pain treatment.

Results: The skin temperature of pain site was lower than non-pain site. The difference of skin temperature improved from 0.65C to 0.39C after oriental treatment and 0.68C to 0.27C after combined treatment. VAS scores improved from 7.9 to 4.7 after oriental treatment and 8.1 to 4.6 after combined treatment. MBI scores improved from 61.40 to 85.00 after oriental treatment and 52.26 to 77.13 after combined treatment.

Conclusions: The difference of skin temperature and Rankin scale scores more significantly improved after western & oriental medical treatment than oriental medical treatment. According to the results, we thought east-west medical management is very useful treatment for CPSP and rehabilitation of the patients with stroke.

PREVENTIVE AND TREATMENT EFFECTS OF THE NMDA-RECEPTOR ANTAGONIST MEMANTINE ON PHANTOM LIMB PAIN
K. Wiech, W. Birbaumer, N. Unertl, K. Preissl, H. Haerle, M. Kiefer, R.T. Toepfner, S. Institute of Medical Psychology & Behavioral Neurobiology, MEG-Center, Tuebingen, Germany

Aim: To evaluate the preventive (study 1) and treatment (study 2) effect of the NMDA-receptor antagonist memantine (p.o.) on phantom limb pain (PLP) after planned or traumatic upper limb amputation.

Methods: In the first study 19 patients scheduled for amputation were randomly assigned to two groups. Group I (N=10) received long-term regional anesthesia (ropivacaine intraoperatively until 7 days after amputation) and the NMDA-antagonist memantine. In group II (N=9) long-term regional anesthesia was combined with placebo. The twelve patients of study 2 who suffered from moderate chronic PLP received memantine or placebo in a cross-over design. In both studies memantine and/or placebo were given over 4 weeks and dose was increased weekly from 10 mg (1st week: 10 mg, 2nd week: 20mg) to 30 mg (3rd and 4th week). The intensity of PLP was rated hourly on a Visual Analogue Scale (0-100) by the patient.

Results: The incidence of PLP in acute patients (study 1) was significantly lower in the memantine than in the placebo group at the one-year follow-up. Moreover, memantine also successfully reduced PLP in patients who had developed PLP early after amputation. PLP intensity did not differ significantly between both groups of study 1 and was < 25 on a VAS at all times of observation. In chronic patients memantine was not able to decrease PLP in comparison to baseline level or placebo.

Conclusions: After upper extremity amputation the NMDA-receptor antagonist memantine should be given as early as possible to prevent the induction and maintenance of phantom limb pain.

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