Ann L. Persson

TENDER OR NOT TENDER: TEST-RETEST REPEATABILITY OF PRESSURE PAIN THRESHOLDS IN THE TRAPEZIUS AND DELTOID MUSCLES OF HEALTHY WOMEN

OBJECTIVE To examine the test-retest repeatability of pressure pain thresholds in the shoulder muscles of healthy women. DESIGN Four experimental sessions (days 1, 3, 28, 30), each including 4 consecutive pressure pain threshold measurements at 10-minute intervals. SUBJECTS Twenty-four healthy female volunteers, mean age 42 years. METHODS Two examiners measured pressure pain thresholds bilaterally over the trapezius and deltoid muscles with an electronic algometer. Students paired t-test, intraclass correlation coefficient, ANOVA repeated measures, 95% confidence interval and mean maximal absolute measurement error, were used for statistics. RESULTS Reliability for each point in all sessions was high; ICC range 0.70-0.94, mean maximal differences; 53-102 kPa (all 4 muscles), and between points in each muscle: ICC right trapezius 0.59-0.77, left 0.67-0.84, right deltoid 0.66-0.83, left 0.70-0.90. Mean maximal differences were 69-101 kPa and 65-111 kPa for the trapezius and deltoid muscles, respectively. The inter-individual variation was 5-fold (trapezius 88-574 kPa; deltoid 91-529 kPa). At the group level, the variation was limited when the first measurement was excluded. Inter-rater and intra-rater repeatability was high without significant differences. Only small side-to-side differences were seen. CONCLUSION Repeated measurements show stable intra-individual values. The method can be recommended when used by trained and experienced examiners.

Pressure pain thresholds and electromyographically defined muscular fatigue induced by a muscular endurance test in normal women.

OBJECTIVE This study was undertaken to examine the relation between muscular tenderness measured as pressure pain thresholds (PPTs) and electromyographic (EMG) signs of fatigue before and after a local standardized static muscle contraction. DESIGN Pressure pain thresholds were measured in the shoulder region before, immediately after, and 10 minutes after a standardized static endurance test while monitoring the EMG signs of local muscular fatigue and its recovery. The study did not address local biochemical issues. SETTING The study was conducted at the Department of Rehabilitation, Lund University Hospital, Lund, Sweden. SUBJECTS Twenty-five healthy female volunteers without musculoskeletal problems participated in this study. INTERVENTION A static endurance test was performed, which consisted of a submaximal unilateral activation of the right trapezius and deltoid muscles for as long as possible. OUTCOME MEASURES Bilateral PPTs over the trapezius and deltoid muscles were measured with an electronic pressure algometer. Established surface EMG parameters of local muscular fatigue were assessed. The Borg Rating of Perceived Exertion scale was used. RESULTS The average endurance time was 330 seconds. Immediately after the test, significant bilateral increases in the normalized PPTs over both muscles were found, although the increase was more pronounced on the test side: over the right trapezius muscle by 13% (p <0.001), over the right deltoid muscle by 23% (p <0.001), and over the left trapezius and deltoid muscles by 6% (p = 0.04) and (p = 0.009), respectively. These increases persisted 10 minutes after the end of the test. The subjects developed significant signs of fatigue as defined by EMG criteria in both muscles on the right side during the test. The recovery from fatigue was approximately half complete 15 seconds after the end of the test and complete or almost complete 10 minutes thereafter. CONCLUSIONS Pressure pain thresholds over shoulder muscles remained elevated up to 10 minutes after a unilateral static endurance test. This time course was completely different from that of EMG-defined muscle fatigue, which showed a fast recovery. These findings indicate that the mechanisms of recovery from fatigue and nociception are independent of each other. The bilateral PPT increases might be explained by central antinociceptive mechanisms activated by static muscle work.

Specific spinal stabilisation exercises in patients with low back pain – a systematic review

Abstract The aim of this review was to evaluate the effects of specific spinal stabilisation exercises in patients with low back pain (LBP). PubMed and PEDro databases were searched. Ten relevant randomised controlled trials (RCTs) with a study population of patients with acute, sub-acute or chronic LBP were reviewed and quality assessed. The intervention method should have included specific spinal stabilisation exercises including co-contraction of multifidus muscles and transversus abdominis muscles. Seven RCTs were high quality and three were low quality. The results indicate moderate evidence of improved disability and/or pain level, increased multifidi cross-sectional area, and limited evidence for improved quality of life after treatment. The outcome measures used showed extensive heterogeneity. Larger, randomised, controlled trials of high quality, in different subgroups of LBP patients, with long-term follow-up are warranted. A standardisation of outcome measures would be beneficial in order to facilitate comparability among studies.

An increased response to experimental muscle pain is related to psychological status in women with chronic non-traumatic neck-shoulder pain.

BackgroundNeck-shoulder pain conditions, e.g., chronic trapezius myalgia, have been associated with sensory disturbances such as increased sensitivity to experimentally induced pain. This study investigated pain sensitivity in terms of bilateral pressure pain thresholds over the trapezius and tibialis anterior muscles and pain responses after a unilateral hypertonic saline infusion into the right legs tibialis anterior muscle and related those parameters to intensity and area size of the clinical pain and to psychological factors (sleeping problems, depression, anxiety, catastrophizing and fear-avoidance).MethodsNineteen women with chronic non-traumatic neck-shoulder pain but without simultaneous anatomically widespread clinical pain (NSP) and 30 age-matched pain-free female control subjects (CON) participated in the study.ResultsNSP had lower pressure pain thresholds over the trapezius and over the tibialis anterior muscles and experienced hypertonic saline-evoked pain in the tibialis anterior muscle to be significantly more intense and locally more widespread than CON. More intense symptoms of anxiety and depression together with a higher disability level were associated with increased pain responses to experimental pain induction and a larger area size of the clinical neck-shoulder pain at its worst.ConclusionThese results indicate that central mechanisms e.g., central sensitization and altered descending control, are involved in chronic neck-shoulder pain since sensory hypersensitivity was found in areas distant to the site of clinical pain. Psychological status was found to interact with the perception, intensity, duration and distribution of induced pain (hypertonic saline) together with the spreading of clinical pain. The duration and intensity of pain correlated negatively with pressure pain thresholds.

Clinical findings in men with chronic pain after falanga torture.

ObjectivesTo explore clinical findings in men with chronic pain after falanga torture as compared with controls, and to try to understand the nature of the pain mechanisms responsible. MethodsEleven male torture victims from the Middle East with chronic pain after falanga, and 11 age, sex, and ethnically matched controls with no history of torture were recruited. All participants were interviewed regarding pain characteristics in the feet and lower legs at rest and when walking. Structural changes and motor and sensory function were clinically assessed according to a standardized protocol. The walking pattern was observed for compensatory gait patterns. ResultsThe torture victims had pain in their feet and lower legs and a compensated gait pattern, usually with severe pain during walking. Reduced light touch and thermal sensation, tactile dysesthesia, allodynia, and tenderness on palpation were common findings. Structural changes in the feet were found in more than half of the victims, but did not correlate with pain reports. These clinical findings were nonexistent or seen only rarely in controls. DiscussionWe found clear clinical signs of nerve injury in the feet. The sensory findings indicated 2 neuropathic pain mechanisms, one dominated by a peripheral pain generator and other by irritative phenomena (dysesthesia, allodynia), indicating central sensitization. It is reasonable to assume that these changes are due to the falanga exposure. A nociceptive contribution cannot be excluded. It is important to perform an individual diagnostic analysis to facilitate adequate treatment.

Are auricular maps reliable for chronic musculoskeletal pain disorders?: A double-blind evaluation

Aim To examine the proposed somatotopic relation between the regions in which patients report musculoskeletal pain and tender points located on the external ears according to a map based on commonly used auricular acupuncture maps. Methods Twenty-five patients (16 women) from a chronic pain clinic were included. Patients were asked, before examination of the external ears, if they had past or present musculoskeletal pain in any of 11 body regions. An ear map, collapsed into 11 zones representing the musculoskeletal system, was used. The ear examiner was blinded to the patients’ pain conditions, medical history and ongoing treatment. Patients communicated with the examiner only to express if tenderness was present in the external ear on palpation using a spring-loaded pressure stylus commonly used for auricular acupuncture. The degree of tenderness was registered on a 5-point scale and dichotomised (no tenderness or tenderness). Agreements between the patients’ painful body regions and tenderness in the external ear zones were presented as percentage, kappa values, sensitivity and specificity. Results The 25 patients reported 116 past or present musculoskeletal pain regions and had 110 tender ear zones. No statistically significant agreements were found between the painful body regions and the corresponding tender ear zones. Conclusions Our results did not show agreements between patients’ reported musculoskeletal pain regions and tender zones in the external ears assessed according to commonly used maps in auricular acupuncture using a pressure stylus. However, very tender points occur on the external ear in a population with chronic musculoskeletal pain.

Relaxation as treatment for chronic musculoskeletal pain - a systematic review of randomised controlled studies

Abstract Objectives: To review studies on relaxation treatment for chronic musculoskeletal pain. Methods: Searches in the databases PubMed, PEDro, CINAHL, Amed, the electronic library information navigator (ELIN), and the British Medical Journal and Science Direct, found 12 relevant studies. Inclusion criteria were: randomised controlled trials (RCTs); studies including a total of at least 25 subjects at the end of intervention; relaxation techniques as single treatment, or combined with education, with the participants being active in the treatment. Results: A total of 12 studies fulfilled all inclusion criteria and were reviewed. Quality assessment showed that all studies were of medium quality. The relaxation techniques used were: progressive muscle relaxation ad modum Jacobson (most common), autogenic training ad modum Schultz, hypnosis, guided imagery and biofeedback. Positive effects were found regarding decreases in pain intensity, anxiety, depression, and fatigue (in fibromyalgia). Even decreases in medication and health costs were seen. Increased mobility and use of coping strategies were also reported. Conclusion: Relaxation training could be effective for patients with chronic musculoskeletal pain. The experimental study designs need to be of improved scientific quality and should, for example, include clear self-training relaxation protocols and suitable control groups. RCTs of high quality are necessary.

Sensory functions in the foot soles in victims of generalized torture, in victims also beaten under the feet (falanga) and in healthy controls – A blinded study using quantitative sensory testing

BackgroundFalanga torture (beatings on the foot soles) produces local chronic pain and severe walking difficulties. We have previously reported signs of neuropathic pain in the feet of falanga victims. The objective here was to clarify underlying pain mechanisms by quantifying sensory impairments in the feet of torture victims who had experienced both generalized torture and those who had been exposed to falanga in addition. An ethnically matched control group was available.MethodsWe employed quantitative sensory testing (QST) by investigators blinded to whether the patients, 32 male torture victims from the Middle East, had (n=15), or had not (n=17) been exposed to falanga. Pain intensity, area and stimulus dependence were used to characterize the pain as were interview data on sensory symptoms. QST included thresholds for touch, cold, warmth, cold-pain, heat-pain, deep pressure pain and wind-up to cutaneous noxious stimuli in the foot soles. Clinical data on anxiety and depression were retrieved.ResultsAlmost all falanga victims had moderate or strong pain in their feet and in twice as large an area of their foot soles as other torture victims. One-third of the latter had no pain in their feet and many reported slight pain; in spite of this, there were no differences in foot sole QST data between the tortured groups. A comparison with normal data indicated that both tortured groups had hypoesthesia for all cutaneous sensory fibre groups except those transmitting cold and heat pain, in addition to deep mechano-nociceptive hyperalgesia.ConclusionA comparison of the QST data between victims having been exposed to generalized torture and victims who in addition had been exposed to falanga, showed no differences on the group level. The sensory disturbances in relation to our control group are compatible with central sensitization and de-sensitization, pointing to a core role of central mechanisms. A further analysis to create individual sensory profiles from our measurements is in progress.

Pain when walking: individual sensory profiles in the foot soles of torture victims - a controlled study using quantitative sensory testing

BackgroundWith quantitative sensory testing (QST) we recently found no differences in sensory function of the foot soles between groups of torture victims with or without exposure to falanga (beatings under the feet). Compared to matched controls the torture victims had hyperalgesia to deep mechano-nociceptive stimuli and hypoesthesia to non-noxious cutaneous stimuli. The purpose of the present paper was to extend the group analysis into individual sensory profiles of victims’ feet to explore possible relations between external violence (torture), reported pain, sensory symptoms and QST data to help clarify the underlying mechanisms.MethodsWe employed interviews and assessments of the pain and sensory symptoms and QST by investigators blinded to whether the patients, 32 male torture victims from the Middle East, had (n=15), or had not (n=17) been exposed to falanga. Pain intensity, area and stimulus dependence were used to characterize the pain. QST included thresholds for touch, cold, warmth, cold-pain, heat-pain, deep pressure pain and wind-up to cutaneous noxious stimuli. An ethnically matched control group was available.The normality criterion, from our control group data, was set as the mean +/− 1.28SD, thus including 80% of all values.QST data were transformed into three categories in relation to our normality range; hypoesthesia, normoesthesia or hyperesthesia/hyperalgesia.ResultsMost patients, irrespective of having been exposed to falanga or not, reported severe pain when walking. This was often associated with hyperalgesia to deep mechanical pressure. Hypoesthesia to mechanical stimuli co-occurred with numbness, burning and with deep mechanical hyperalgesia more often than not, but otherwise, a hypoesthesia to cutaneous sensory modalities did not co-occur systematically to falanga, pain or sensory symptoms.ConclusionIn torture victims, there seem to be overriding mechanisms, manifested by hyperalgesia to pressure pain, which is usually considered a sign of centralization. In addition there was cutaneous hypoesthesia, but since there was no obvious correlation to the localization of trauma, these findings may indicate centrally evoked disturbances in sensory transmission, that is, central inhibition. We interpret these findings as a sign of changes in central sensory processing as the unifying pathological mechanism of chronic pain in these persons.

Validity of electrical stimulus magnitude matching in chronic pain

OBJECTIVE To examine the validity of the PainMatcher in chronic pain. DESIGN Comparison of parallel pain estimates from visual analogue scales with electrical stimulus magnitude matching. PATIENTS Thirty-one patients with chronic musculoskeletal pain. METHODS Twice a day ongoing pain was rated on a standard 100-mm visual analogue scale, and thereafter magnitude matching was performed using a PainMatcher. The sensory threshold to electrical stimulation was tested twice on separate occasions. RESULTS In 438 observations visual analogue scale ranged from 3 to 95 (median 41) mm, and PainMatcher magnitudes from 2.67 to 27.67 (median 6.67; mean 7.78) steps. There was little correlation between visual analogue scale and magnitude data (r = 0.29; p < 0.0001). The mean sensory threshold was 3.67 steps, indicating that the PainMatcher, on average, stimulated at 2.1 times the perception threshold at matching point. CONCLUSION Electrical magnitude matching of chronic pain intensity elicited limited activation of nerve fibres at 2.0-2.2 times sensory threshold, indicating that the induced pain was evoked by coarse nociceptive Adelta fibres. While the visual analogue scale estimates covered the whole range of the instrument, the PainMatcher readings utilized only a small part of the instrument range and, importantly, had little or no relation to the visual analogue scale estimates. The validity of the PainMatcher procedure is doubtful.