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760 PHYSIOTHERAPISTS' INITIAL TELEPHONE CONSULTATIONS REGARDING BACK PAIN – A METHOD TO ANALYSE SCREENING FOR RISK FACTORS
Poster Sessions / European Journal of Pain 13 (2009) S55–S285
when he/she presents pain behaviours conveying distress or when medical evidence (ME) of pathology is absent (Tait et al., 2009). We aimed at understanding whether the influence of such variables might be moderated by the patient’s sex. In fact, findings suggest that perceptions of members of low-status groups, like women, are more dependent on contextual cues than perceptions of members of high-status groups (Lorenzi-Cioldi, 2002). Consequently, we expected that judgments of a woman’s pain would be more influenced by her pain behaviours and the ME than judgments of a man’s pain. Method: 126 female nurses participated in an experimental between-subjects design, 2 (patient’s sex) ×2 (stoicism pain behaviours: absent vs. present) ×2 (ME: absent vs. present). These variables were manipulated by written vignettes depicting a chronic low-back pain patient going into an E.R. Nurses judged the patient’s pain on several dimensions: 1) credibility; 2) disability; 3) severity of the clinical situation; 4) psychological attributions (alpha >0.80) Results: Nurses under-valued the patient’s pain in the absence of stoicism behaviours or ME. However, only the effect of ME was moderated by the patient’s sex; in the absence of ME the woman’s pain was perceived as more psychological, less credible and disabling Conclusion: These findings highlight the need to further explore the extent to which women are more vulnerable to providers’ pain assessment biases than men 758 COGNITIVE PERFORMANCE AND MEMORY COMPLAINTS: DIFFERENCES BETWEEN CHRONIC PAIN PATIENTS AND HEALTHY CONTROLS A. Castel *, R. Cascon, A. Padrol, J. Sala, N. Aragones, M. Perez, ´ M. Rull. Pain Clinic. Hospital Universitari de Tarragona Joan XXIII. Spain, Tarragona, Spain Background and Aims: Memory complaints are usual in chronic pain patients. Aims: 1) To compare cognitive performance in chronic pain patients (CPP) and healthy controls (HC). 2) To compare cognitive complaints in both groups of subjects. Subjects: 204 participants (21–64 years old). 160 patients with chronic pain and 44 control subjects. Mean age 48.5 (S.D. 9.6). 26.5% men,73.5% women. Method: Subjects were individually examined by a psychologist. Verbal memory was measured with the Verbal Learning Test – TAVEC, attention with the Toulouse-Pieron ´ Test, interference with the Stroop Color and Word Test, and memory complaints with the Memory Failures in Everyday Memory Test. Results: 1) Demographic variables: There were no differences in educational level between both groups. HC were younger than CPP [t (202) = 5.23; p < 0.05]. 2) Cognitive performance: CPP have worse cognitive performance in immediate memory [t (200) = 2.166; p < 0.0001], free short term recall [t (200) = 0.693; p < 0.05], free long term recall [t (200) = 2.240; p < 0.05], semantic organization in long term recall [t (200) = 1.218; p < 0.05], attention [t (200) = 0.754; p < 0.0001], color-Stroop [t (200) = 0.061; p < 0.05], and word-colorStroop [t (200) = 1.635; p < 0.05]. 3) Subjective symptoms: CPP expressed more memory complaints than HC [t (202) = 37.18; p < 0.0001]. Conclusions: 1) CPP have a worse cognitive performance than HC in some aspects of verbal memory, attention and interference. 2) CPP have more memory complaints than HC. 3) One important limitation of this work was the age difference between CPP and HC.
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759 COGNITIVE PERFORMANCE AND MEMORY COMPLAINTS IN CHRONIC PAIN PATIENTS: PREDICTOR VARIABLES A. Castel *, M. Salvat, A. Padrol, R. Perin˜ an, ´ J. Sala, M. Segura, R. Maria. Pain Clinic. Hospital Universitari de Tarragona Joan XXIII. Spain, Tarragona, Spain Background and Aims: Memory complaints and specific cognitive deficit seems usual in chronic pain patients. Aims: 1) To determinate the predictor variables about cognitive performance in chronic pain patients. 2) To determinate the predictor variables about memory complaints. Subjects: 160 patients (21–64 years old). Mean age 49.2 (S.D. 9.0). 26.9% men, 73.1% women. 26.3% not completed primary school, 46.9% completed primary education, 18.8% completed secondary education, 8.1% completed higher education. Method: Subjects were individually examined by a psychologist. Verbal memory was measured with the Verbal Learning Test – TAVEC, attention with the Toulouse-Pieron ´ Test, memory complaints with the Memory Failures in Everyday Memory Test. Anxiety and depression with the Hospital Anxiety and Depression Scale. Regression analysis was performed (stepwise method). Results: Pain intensity does not explain cognitive impairment in chronic pain patients. Educational level explains the 10.7% of the variance in immediate memory. In short term memory, depression and anxiety explain the 5.9%. In long term memory educational level explains the 4.9% of the variance, and depression the 4.1%. Respect to attention, educational level explains the 14.7% of the variance, and age the 6.2%. Depression explains the 29.8% of the memory complaints in chronic pain patients. Anxiety explains the 2.8% of the variance. None other variable was predictor of memory complaints. Conclusions: 1) Pain intensity is not a predictive variable of the grade of cognitive impairment. 2) In our sample, educational level seems to be the more important predictive variable for some cognitive performance. 3) Memory complaints are related to depression. 760 PHYSIOTHERAPISTS’ INITIAL TELEPHONE CONSULTATIONS REGARDING BACK PAIN – A METHOD TO ANALYSE SCREENING FOR RISK FACTORS ˚ of. ¨ Uppsala I. Demmelmaier *, P. Lindberg, E. Denison, P. Asenl University, Uppsala, Sweden Background and Aim: There is a gap between guidelines and clinical management of psychosocial risk factors for prolonged disability in back pain. This study concerns physiotherapists’ screening of risk factors in initial telephone consultations regarding back pain. The aim was to develop and test a reliable method to analyse such consultations within primary health care. Method: The material consisted of 17 initial telephone consultations regarding back pain that were recorded by five physiotherapists during 2007 and 2008. A protocol was developed that covered eight evidence-based risk factors. The first author and two independent investigators performed separate analyses according to the protocol. Consultation time spent on six predefined topics was measured. Results: Intraclass correlation of how many risk factors were investigated was 0.82 (p < 0.001.) Kappa values (pair-wise) of which risk factors that were examined were 0.79, 0.73 and 0.66 (p < 0.001). A median of 2 (range 0–4) risk factors were examined; most frequent was history/signs of serious spinal pathology, followed by sick leave, disability and coping. Rating of pain intensity, the patient’s beliefs about pain, depression and expectations of longterm pain were not examined. The consultation time (mean 8.5 minutes, range 3–21 minutes) was spent on description of pain (35%), administrative matters (30%), actions (21%), risk factors (11%), general health behaviour (2%) and patient expectations (1%).
S220
Poster Sessions / European Journal of Pain 13 (2009) S55–S285
Conclusions: The method of analysis appears reliable. It will be used in an intervention study that evaluates to what extent physiotherapists can learn to screen in concordance with guidelines in initial telephone consultations.
tissue during muscle pain perception suggests that the sensitivity of mechanosensitive nociceptors in the deep tissue is lower than the nociceptors in the superficial layers.
761 VALIDATING IMPACT RECOMMENDATIONS FOR MINIMAL, MODERATE OR SUBSTANTIAL BENEFIT S. Derry1 , A. Moore1 *, S. Straube2 , H. McQuay1 . 1 University of Oxford, Oxford, United Kingdom; 2 University of G¨ ottingen, G¨ ottingen, Germany
763 RELIABILITY AND VALIDITY OF THE SPANISH VERSION OF THE TAMPA SCALE FOR KINESIOPHOBIA (TSK) IN CHRONIC AND ACUTE PAIN PATIENTS L. Gomez ´ Perez ´ *, A.E. Lopez ´ Mart´ınez, G.T. Ru´ız Parraga. ´ Departamento de Personalidad, Evaluaci´ on y Tratamiento psicol´ ogico. Universidad de M´ alaga., M´ alaga, Spain
Background: In 2008 the IMMPACT group defined provisional benchmarks for interpreting change in chronic pain clinical trial outcome measures. For pain intensity (PI), a moderately important change was defined as ≥ 30% decrease in PI, and a substantial improvement was ≥ 50% decrease. For patient global impression of change (PGIC) a moderately important change was much improved, and substantial was very much improved. Methods: Individual patient meta-analysis of four randomised trials of pregabalin in fibromyalgia with 2757 patients over 8–12 weeks. IMMPACT criteria of minimal, moderate, and substantial benefit were calculated for each patient using baseline and end of trial weekly average PI measures, and PGIC at end of trial. Results were calculated separately for placebo, and 300, 450, and 600 mg pregabalin daily. Results: For minimal benefit, PGIG and PI gave the same proportion of patients for pregablin 600 mg, but about 50% more for placebo and pregabalin 300 and 450 mg doses. For moderate benefit, PGIC and PI gave very similar results. For substantial benefit, PGIC consistently produced fewer patients than PI, by 30–50%. Conclusions: IMMPACT provisional benchmarks for minimal, moderate, and substantial benefits can be measured by using reduction in PI and by PGIC at the end of the trial. For moderate improvement there is good evidence that both scales produce the same result in fibromyalgia, but PGIC definitions overstate minimal benefit and understate substantial benefit relative to PI definitions. Validation in other pain conditions is needed.
Background and Aims: studies analysing the psychometric properties of the Spanish version of the TSK have not been conducted up to now. The aim of this study was to analyse the reliability and validity of the Spanish version of the TSK-11 in two different samples: a chronic pain sample (n = 125) and a musculoskeletal acute pain sample (n = 86). Method: patients completed the TSK-11, Pain Numerical rating scale, Fear Avoidance Beliefs Questionnaire, Pain Catastrophizing Scale, Hospital Anxiety and Depression Scale (HADS) and the Impairment and Functioning Inventory (IFI) in their clinical setting. Results: TSK-11 as well as its two factors (named Activity Avoidance and Harm) shows good reliability (internal consistency and stability) and validity (convergent and predictive). In addition, evidence on discriminant validity between TSK-11 factors is provided. The Harm factor shows the best predictive validity, as it predicts pain persistence, catastrophizing, depression, and pain intensity scores 6 months later. The Changes in Activity Avoidance factor are positively correlated with changes in catastrophizing and anxiety, and negatively associated with changes in functional status. Conclusions: the results of this study show that TSK-11 is suitable to measure pain-related fear in both chronic and acute pain patients. Evidence that supports the contribution of both components of pain-related fear to pain adjustment is provided, highlighting the fact that both dimensions play an important role in the evolution and maintenance of pain.
762 THE RELATION BETWEEN MECHANICAL PROPERTIES OF TISSUES AND THE SENSATION OF MUSCLE PAIN DURING PRESSURE STIMULATION S. Finocchietti *, M. Nielsen, T. Graven-Nielsen. Center for Sensory-Motor Interaction, Aalborg University, Aalborg, Denmark
764 REPRODUCIBILITY OF PAIN VISION M. Ito1 *, H. Yamamoto2 , K. Ohtsuka2 , T. Matsushita1 . 1 Department of Orthopaedics, Teikyo University, Tokyo, Japan; 2 Ageo Central General Hospital, Ageo, Japan
Background: Pressure algometry is a common method for deep tissue sensitivity assessment. In this study, the perception of muscle pain is related to the stress and strain distribution in tissues undergoing pressure stimulation with different probe diameters. Methods: A 3 dimensional finite-element model is developed to describe the stress and strain distribution in the human lower leg tissues during pressure algometry with different probe diameters (0.5;1.0;1.5 cm). To validate the model, the relation between tissue indentation and pressure stimulation intensity is extracted and compared with data obtained by experimentally recorded pressure pain thresholds (PPTs) from 8 subjects. Results: PPTs were associated with indentations in the range of 0.8–1.2 cm which are comparable with the simulation model. The principal stress peaked in the skin layer and was reduced to about 10% in the muscle tissue. The principal strain peaked in the adipose tissue and was reduced in the muscle tissue to about 66% (thinner probe) and 80% (larger probe). The percentage of maximal vonMises stress is increasing from 1% with the 0.5 cm probe to 5% with the 1.5 cm probe. Conclusion: The higher values of strain versus stress suggest that muscle pain evoked by pressure stimulation is mainly related to the strain and that larger probes are most useful for pressureinduced muscle pain. The general higher stress in the superficial
There is no appropriate method other than a subjective evaluationbased parameter, the VAS score. Pain Vision (Nipro, Inc.) became commercially available as a new device to objectively assess pain. We investigated clinical reproducibility of this device. The subjects were 152 adults. Pain Vision facilitates the measurement of pain as the value with electric current that does not stimulate C fibers. Electric current perceived as the same volume as pain is determined, and divided by the reference value (threshold) which is the minimum current volume to express the grade of pain as numerical values (pain score). We measured the threshold 4 times to investigate its variations. Furthermore we prepared 100, 200, and 300 g stimulation device, measured pain score and the VAS score. The above procedure was performed twice on different days. On the first day of measurement, the thresholds on the 1st , 2nd , 3rd , and 4th measurements were 9.8±2.2, 8.8±2.2, 8.7±2.5, and 8.8±2.3, respectively. On the second day, the thresholds were 9.7±2.5, 8.7±2.3, 8.8±2.5, and 8.9±2.5 with no significant differences. However, the values on the 1st measurement were slightly higher. The pain scores for 100, 200, and 300 g showed no significant differences between the two days, confirming the reproducibility of this parameter. The VAS scores for 100 and 200 g on the first day of measurement were 32.2±22.1 and 31.1±18 with no marked difference, the score for 200 g was lower.
when he/she presents pain behaviours conveying distress or when medical evidence (ME) of pathology is absent (Tait et al., 2009). We aimed at understanding whether the influence of such variables might be moderated by the patient’s sex. In fact, findings suggest that perceptions of members of low-status groups, like women, are more dependent on contextual cues than perceptions of members of high-status groups (Lorenzi-Cioldi, 2002). Consequently, we expected that judgments of a woman’s pain would be more influenced by her pain behaviours and the ME than judgments of a man’s pain. Method: 126 female nurses participated in an experimental between-subjects design, 2 (patient’s sex) ×2 (stoicism pain behaviours: absent vs. present) ×2 (ME: absent vs. present). These variables were manipulated by written vignettes depicting a chronic low-back pain patient going into an E.R. Nurses judged the patient’s pain on several dimensions: 1) credibility; 2) disability; 3) severity of the clinical situation; 4) psychological attributions (alpha >0.80) Results: Nurses under-valued the patient’s pain in the absence of stoicism behaviours or ME. However, only the effect of ME was moderated by the patient’s sex; in the absence of ME the woman’s pain was perceived as more psychological, less credible and disabling Conclusion: These findings highlight the need to further explore the extent to which women are more vulnerable to providers’ pain assessment biases than men 758 COGNITIVE PERFORMANCE AND MEMORY COMPLAINTS: DIFFERENCES BETWEEN CHRONIC PAIN PATIENTS AND HEALTHY CONTROLS A. Castel *, R. Cascon, A. Padrol, J. Sala, N. Aragones, M. Perez, ´ M. Rull. Pain Clinic. Hospital Universitari de Tarragona Joan XXIII. Spain, Tarragona, Spain Background and Aims: Memory complaints are usual in chronic pain patients. Aims: 1) To compare cognitive performance in chronic pain patients (CPP) and healthy controls (HC). 2) To compare cognitive complaints in both groups of subjects. Subjects: 204 participants (21–64 years old). 160 patients with chronic pain and 44 control subjects. Mean age 48.5 (S.D. 9.6). 26.5% men,73.5% women. Method: Subjects were individually examined by a psychologist. Verbal memory was measured with the Verbal Learning Test – TAVEC, attention with the Toulouse-Pieron ´ Test, interference with the Stroop Color and Word Test, and memory complaints with the Memory Failures in Everyday Memory Test. Results: 1) Demographic variables: There were no differences in educational level between both groups. HC were younger than CPP [t (202) = 5.23; p < 0.05]. 2) Cognitive performance: CPP have worse cognitive performance in immediate memory [t (200) = 2.166; p < 0.0001], free short term recall [t (200) = 0.693; p < 0.05], free long term recall [t (200) = 2.240; p < 0.05], semantic organization in long term recall [t (200) = 1.218; p < 0.05], attention [t (200) = 0.754; p < 0.0001], color-Stroop [t (200) = 0.061; p < 0.05], and word-colorStroop [t (200) = 1.635; p < 0.05]. 3) Subjective symptoms: CPP expressed more memory complaints than HC [t (202) = 37.18; p < 0.0001]. Conclusions: 1) CPP have a worse cognitive performance than HC in some aspects of verbal memory, attention and interference. 2) CPP have more memory complaints than HC. 3) One important limitation of this work was the age difference between CPP and HC.
S219
759 COGNITIVE PERFORMANCE AND MEMORY COMPLAINTS IN CHRONIC PAIN PATIENTS: PREDICTOR VARIABLES A. Castel *, M. Salvat, A. Padrol, R. Perin˜ an, ´ J. Sala, M. Segura, R. Maria. Pain Clinic. Hospital Universitari de Tarragona Joan XXIII. Spain, Tarragona, Spain Background and Aims: Memory complaints and specific cognitive deficit seems usual in chronic pain patients. Aims: 1) To determinate the predictor variables about cognitive performance in chronic pain patients. 2) To determinate the predictor variables about memory complaints. Subjects: 160 patients (21–64 years old). Mean age 49.2 (S.D. 9.0). 26.9% men, 73.1% women. 26.3% not completed primary school, 46.9% completed primary education, 18.8% completed secondary education, 8.1% completed higher education. Method: Subjects were individually examined by a psychologist. Verbal memory was measured with the Verbal Learning Test – TAVEC, attention with the Toulouse-Pieron ´ Test, memory complaints with the Memory Failures in Everyday Memory Test. Anxiety and depression with the Hospital Anxiety and Depression Scale. Regression analysis was performed (stepwise method). Results: Pain intensity does not explain cognitive impairment in chronic pain patients. Educational level explains the 10.7% of the variance in immediate memory. In short term memory, depression and anxiety explain the 5.9%. In long term memory educational level explains the 4.9% of the variance, and depression the 4.1%. Respect to attention, educational level explains the 14.7% of the variance, and age the 6.2%. Depression explains the 29.8% of the memory complaints in chronic pain patients. Anxiety explains the 2.8% of the variance. None other variable was predictor of memory complaints. Conclusions: 1) Pain intensity is not a predictive variable of the grade of cognitive impairment. 2) In our sample, educational level seems to be the more important predictive variable for some cognitive performance. 3) Memory complaints are related to depression. 760 PHYSIOTHERAPISTS’ INITIAL TELEPHONE CONSULTATIONS REGARDING BACK PAIN – A METHOD TO ANALYSE SCREENING FOR RISK FACTORS ˚ of. ¨ Uppsala I. Demmelmaier *, P. Lindberg, E. Denison, P. Asenl University, Uppsala, Sweden Background and Aim: There is a gap between guidelines and clinical management of psychosocial risk factors for prolonged disability in back pain. This study concerns physiotherapists’ screening of risk factors in initial telephone consultations regarding back pain. The aim was to develop and test a reliable method to analyse such consultations within primary health care. Method: The material consisted of 17 initial telephone consultations regarding back pain that were recorded by five physiotherapists during 2007 and 2008. A protocol was developed that covered eight evidence-based risk factors. The first author and two independent investigators performed separate analyses according to the protocol. Consultation time spent on six predefined topics was measured. Results: Intraclass correlation of how many risk factors were investigated was 0.82 (p < 0.001.) Kappa values (pair-wise) of which risk factors that were examined were 0.79, 0.73 and 0.66 (p < 0.001). A median of 2 (range 0–4) risk factors were examined; most frequent was history/signs of serious spinal pathology, followed by sick leave, disability and coping. Rating of pain intensity, the patient’s beliefs about pain, depression and expectations of longterm pain were not examined. The consultation time (mean 8.5 minutes, range 3–21 minutes) was spent on description of pain (35%), administrative matters (30%), actions (21%), risk factors (11%), general health behaviour (2%) and patient expectations (1%).
S220
Poster Sessions / European Journal of Pain 13 (2009) S55–S285
Conclusions: The method of analysis appears reliable. It will be used in an intervention study that evaluates to what extent physiotherapists can learn to screen in concordance with guidelines in initial telephone consultations.
tissue during muscle pain perception suggests that the sensitivity of mechanosensitive nociceptors in the deep tissue is lower than the nociceptors in the superficial layers.
761 VALIDATING IMPACT RECOMMENDATIONS FOR MINIMAL, MODERATE OR SUBSTANTIAL BENEFIT S. Derry1 , A. Moore1 *, S. Straube2 , H. McQuay1 . 1 University of Oxford, Oxford, United Kingdom; 2 University of G¨ ottingen, G¨ ottingen, Germany
763 RELIABILITY AND VALIDITY OF THE SPANISH VERSION OF THE TAMPA SCALE FOR KINESIOPHOBIA (TSK) IN CHRONIC AND ACUTE PAIN PATIENTS L. Gomez ´ Perez ´ *, A.E. Lopez ´ Mart´ınez, G.T. Ru´ız Parraga. ´ Departamento de Personalidad, Evaluaci´ on y Tratamiento psicol´ ogico. Universidad de M´ alaga., M´ alaga, Spain
Background: In 2008 the IMMPACT group defined provisional benchmarks for interpreting change in chronic pain clinical trial outcome measures. For pain intensity (PI), a moderately important change was defined as ≥ 30% decrease in PI, and a substantial improvement was ≥ 50% decrease. For patient global impression of change (PGIC) a moderately important change was much improved, and substantial was very much improved. Methods: Individual patient meta-analysis of four randomised trials of pregabalin in fibromyalgia with 2757 patients over 8–12 weeks. IMMPACT criteria of minimal, moderate, and substantial benefit were calculated for each patient using baseline and end of trial weekly average PI measures, and PGIC at end of trial. Results were calculated separately for placebo, and 300, 450, and 600 mg pregabalin daily. Results: For minimal benefit, PGIG and PI gave the same proportion of patients for pregablin 600 mg, but about 50% more for placebo and pregabalin 300 and 450 mg doses. For moderate benefit, PGIC and PI gave very similar results. For substantial benefit, PGIC consistently produced fewer patients than PI, by 30–50%. Conclusions: IMMPACT provisional benchmarks for minimal, moderate, and substantial benefits can be measured by using reduction in PI and by PGIC at the end of the trial. For moderate improvement there is good evidence that both scales produce the same result in fibromyalgia, but PGIC definitions overstate minimal benefit and understate substantial benefit relative to PI definitions. Validation in other pain conditions is needed.
Background and Aims: studies analysing the psychometric properties of the Spanish version of the TSK have not been conducted up to now. The aim of this study was to analyse the reliability and validity of the Spanish version of the TSK-11 in two different samples: a chronic pain sample (n = 125) and a musculoskeletal acute pain sample (n = 86). Method: patients completed the TSK-11, Pain Numerical rating scale, Fear Avoidance Beliefs Questionnaire, Pain Catastrophizing Scale, Hospital Anxiety and Depression Scale (HADS) and the Impairment and Functioning Inventory (IFI) in their clinical setting. Results: TSK-11 as well as its two factors (named Activity Avoidance and Harm) shows good reliability (internal consistency and stability) and validity (convergent and predictive). In addition, evidence on discriminant validity between TSK-11 factors is provided. The Harm factor shows the best predictive validity, as it predicts pain persistence, catastrophizing, depression, and pain intensity scores 6 months later. The Changes in Activity Avoidance factor are positively correlated with changes in catastrophizing and anxiety, and negatively associated with changes in functional status. Conclusions: the results of this study show that TSK-11 is suitable to measure pain-related fear in both chronic and acute pain patients. Evidence that supports the contribution of both components of pain-related fear to pain adjustment is provided, highlighting the fact that both dimensions play an important role in the evolution and maintenance of pain.
762 THE RELATION BETWEEN MECHANICAL PROPERTIES OF TISSUES AND THE SENSATION OF MUSCLE PAIN DURING PRESSURE STIMULATION S. Finocchietti *, M. Nielsen, T. Graven-Nielsen. Center for Sensory-Motor Interaction, Aalborg University, Aalborg, Denmark
764 REPRODUCIBILITY OF PAIN VISION M. Ito1 *, H. Yamamoto2 , K. Ohtsuka2 , T. Matsushita1 . 1 Department of Orthopaedics, Teikyo University, Tokyo, Japan; 2 Ageo Central General Hospital, Ageo, Japan
Background: Pressure algometry is a common method for deep tissue sensitivity assessment. In this study, the perception of muscle pain is related to the stress and strain distribution in tissues undergoing pressure stimulation with different probe diameters. Methods: A 3 dimensional finite-element model is developed to describe the stress and strain distribution in the human lower leg tissues during pressure algometry with different probe diameters (0.5;1.0;1.5 cm). To validate the model, the relation between tissue indentation and pressure stimulation intensity is extracted and compared with data obtained by experimentally recorded pressure pain thresholds (PPTs) from 8 subjects. Results: PPTs were associated with indentations in the range of 0.8–1.2 cm which are comparable with the simulation model. The principal stress peaked in the skin layer and was reduced to about 10% in the muscle tissue. The principal strain peaked in the adipose tissue and was reduced in the muscle tissue to about 66% (thinner probe) and 80% (larger probe). The percentage of maximal vonMises stress is increasing from 1% with the 0.5 cm probe to 5% with the 1.5 cm probe. Conclusion: The higher values of strain versus stress suggest that muscle pain evoked by pressure stimulation is mainly related to the strain and that larger probes are most useful for pressureinduced muscle pain. The general higher stress in the superficial
There is no appropriate method other than a subjective evaluationbased parameter, the VAS score. Pain Vision (Nipro, Inc.) became commercially available as a new device to objectively assess pain. We investigated clinical reproducibility of this device. The subjects were 152 adults. Pain Vision facilitates the measurement of pain as the value with electric current that does not stimulate C fibers. Electric current perceived as the same volume as pain is determined, and divided by the reference value (threshold) which is the minimum current volume to express the grade of pain as numerical values (pain score). We measured the threshold 4 times to investigate its variations. Furthermore we prepared 100, 200, and 300 g stimulation device, measured pain score and the VAS score. The above procedure was performed twice on different days. On the first day of measurement, the thresholds on the 1st , 2nd , 3rd , and 4th measurements were 9.8±2.2, 8.8±2.2, 8.7±2.5, and 8.8±2.3, respectively. On the second day, the thresholds were 9.7±2.5, 8.7±2.3, 8.8±2.5, and 8.9±2.5 with no significant differences. However, the values on the 1st measurement were slightly higher. The pain scores for 100, 200, and 300 g showed no significant differences between the two days, confirming the reproducibility of this parameter. The VAS scores for 100 and 200 g on the first day of measurement were 32.2±22.1 and 31.1±18 with no marked difference, the score for 200 g was lower.