Jan Ekholm

Sensory dysfunction in fibromyalgia patients with implications for pathogenic mechanisms.

&NA; This study, addressing etiologic and pathogenic aspects of fibromyalgia (FM), aimed at examining whether sensory abnormalities in FM patients are generalized or confined to areas with spontaneous pain. Ten female FM patients and 10 healthy, age‐matched females participated. The patients were asked to rate the intensity of ongoing pain using a visual analogue scale (VAS) at the site of maximal pain, the homologous contralateral site and two homologous sites with no or minimal pain. Quantitative sensory testing was performed for assessment of perception thresholds in these four sites. Von Frey filaments were used to test low‐threshold mechanoreceptive function. Pressure pain sensitivity was assessed with a pressure algometer and thermal sensitivity with a Thermotest®. In addition the stimulus‐response curve of pain intensity as a function of graded nociceptive heat stimulation was studied at the site of maximal pain and at the homologous contralateral site. FM patients had increased sensitivity to non‐painful warmth (P < 0.01) over painful sites and a tendency to increased sensitivity to non‐painful cold (P < 0.06) at all sites compared to controls, but there was no difference between groups regarding tactile perception thresholds. Compared to controls, patients demonstrated increased sensitivity to pressure pain (P < 0.001), cold pain (P < 0.001) and heat pain (P < 0.02) over all tested sites. The stimulus‐response curve was parallely shifted to the left of the curve obtained from controls (P < 0.003). Intragroup comparisons showed that patients had increased sensitivity to pressure pain (P < 0.01) and light touch (P < 0.05) in the site of maximal pain compared to the homologous contralateral site. These findings could be explained in terms of sensitization of primary afferent pathways or as a dysfunction of endogenous systems modulating afferent activity. However, the generalized increase in sensitivity found in FM patients was unrelated to spontaneous pain and thus most likely due to a central nervous system (CNS) dysfunction. The additional hyperphenomena related to spontaneous pain are probably dependent on disinhibition/facilitation of nociceptive afferent input from normal (or ischemic) muscles.

Modulation of pressure pain thresholds during and following isometric contraction in patients with fibromyalgia and in healthy controls

&NA; This study aimed at evaluating the influence of submaximal isometric contraction on pressure pain thresholds (PPTs) in 14 fibromyalgia (FM) patients and 14 healthy volunteers, before and after skin hypoesthesia. PPTs were determined with pressure algometry over m. quadriceps femoris before, during and following an isometric contraction. Maximum voluntary contraction (MVC) was assessed using a computerized dynamometer. A contraction of 22% MVC on average was held until exhaustion (max. 5 min) and PPTs were assessed every 30 sec. A local anesthetic cream and a control cream were applied following a double‐blind design and PPTs were reassessed. In healthy volunteers,PPTs increased during contraction (P < 0.001), then decreased after the end of contraction (P < 0.001) but remained above precontraction values during the 5 min of post‐contraction assessments (P < 0.001). In FM patients PPTs decreased in the middle of the contraction period (P < 0.05) and remained below precontraction levels during the rest of the contraction period (P < 0.05) and during the 5 min of post‐contraction assessment (immediately post‐contraction NS; 2.5 min post‐contraction P < 0.01; 5 min post‐contraction P < 0.05). The normalized PPTs were significantly lower in patients than in controls during contraction (start P < 0.01; middle P < 0.001; end P < 0.001.) and at all times during post‐contraction assessments (P < 0.001). Anesthetic cream raised PPTs at rest in controls (P < 0.01) but not in FM patients, and did not influence contraction or post‐contraction PPTs in either group. Therefore, the increased pressure pain sensibility in FM patients is more pronounced deep to the skin. The observed decrease of PPTs during isometric contraction in FM patients could be due to sensitization of mechanonociceptors caused by muscle ischemia and/or dysfunction in pain modulation during muscle contraction.

Effects of changes in sitting work posture on static neck and shoulder muscle activity

Abstract In order to analyse the effect of changing the sitting posture on the level of neck and shoulder muscular activity, an electromyographic (EMG) study of ten healthy experienced female workers from an electronics plant was undertaken. A standardized, simulated task was performed in eight different sitting work postures. Using surface electrodes, the level of muscular activity was recorded as normalized, full-wave rectified low-pass filtered EMG. The results showed that the whole spine flexed sitting posture gave higher levels of static activity in several neck and shoulder muscles than the posture with a straight and vertical spine, which in turn gave higher levels than the posture with slightly backward-inclined thoraco-lumbar spine.

Load moments and myoelectric activity when the cervical spine is held in full flexion and extension

Abstract Sustained joint load in extreme positions (namely maximally flexed or extended positions) has been described as causing pain. The aim of the present study is to analyse eight different sitting work postures with respect to extreme positions, and to assess the mechanical load and the levels of muscular activity arising in defined extreme positions of the cervical spine. Ten healthy female workers from an electronics plant took part in laboratory experiments. For seven of these, levels of neck and shoulder muscular activity in sitting postures with the cervical spine in different manually-adjusted extreme positions were recorded using surface electrodes. Loading moments of force about the bilateral motion axis of the atlanto-occipital joint (Occ-C1) and the spinal cervico-thoractc motion segments (C7-T1) were calculated. Extreme or almost extreme positions occurred in sitting postures with the thoracolumbar back inclined slightly backwards or with the whole spine flexed. Electromyographic (EMG) act...

Tibiofemoral joint forces during isokinetic knee extension

Using a Cybex II, eight healthy male subjects performed isokinetic knee extensions at two different speeds (30 and 180 deg/sec) and two different positions of the resistance pad (proximal and distal). A sagittal plane, biomechanical model was used for calculating the mag nitude of the tibiofemoral joint compressive and shear forces. The magnitude of isokinetic knee extending moments was found to be significantly lower with the resistance pad placed proximally on the leg instead of distally. The tibiofemoral compressive force was of the same magnitude as the patellar tendon force, with a maximum of 6300 N or close to 9 times body weight (BW). The tibiofemoral shear force changed direction from being negative (tibia tends to move posteriorly in relation to femur) to a positive magnitude of about 700 N or close to 1 BW, indicating that high forces arise in the ACL when the knee is extended more than 60°. The anteriorly directed shear force was lowered consid erably by locating the resistance pad to a proximal position on the leg. This model may be used when it is desirable to control stress on the ACL, e.g., in the rehabilitative period after ACL repairs or reconstruc tions.

FROM SHAME TO RESPECT: MUSCULOSKELETAL PAIN PATIENTS' EXPERIENCE OF A REHABILITATION PROGRAMME, A QUALITATIVE STUDY

OBJECTIVE This study aimed to describe and analyse how participants with fibromyalgia or chronic, widespread, musculoskeletal pain, 1 year after completion, experienced a rehabilitation programme; and what knowledge and strategies they had gained. DESIGN, METHODS AND SUBJECTS: Semi-structured interviews with 16 female patients were analysed using the grounded theory method of constant comparison. RESULTS One core category, from shame to respect, and 4 categories, developing body awareness/knowledge, setting limits, changing self-image and negative counterbalancing factors, and hopelessness and frustration over ones employment situation emerged from the data. The core category represents a process where the informants changed emotionally. Three categories were identified as important for starting and maintaining the process, one category affected the process negatively. CONCLUSION The rehabilitation programme started the process of change, from shame to respect. The informants learned new strategies for handling their pain and other symptoms; they improved their self-image and communication in their social environment.

Modulation of pressure pain thresholds during and following isometric contraction

&NA; This study aimed at evaluating the influence of submaximal isometric contraction on pressure pain thresholds (PPTs) in 14 healthy volunteers before and after skin hypoesthesia. PPTs were determined with pressure algometry over m. quadriceps femoris before, during, and following an isometric contraction. Maximum voluntary contraction (MVC) was assessed using a computerized dynamometer. A contraction of 21% MVC was held until exhaustion (max: 5 min) and PPTs were assessed every 30 sec. A local anesthetic cream and a control cream were applied following a double‐blind design and PPTs were reassessed. PPTs increased significantly at the start of contraction and continued to increase until the middle of the contraction period, then remaining at this level. After contraction PPTs decreased significantly but for 5 min remained slightly above precontraction levels. Anesthetic cream raised PPT at rest but not during and following contraction. The relative increase in PPTs during and immediately following isometric contraction was lower with anesthetic cream. Isometric contraction of m. quadriceps femoris increase PPTs during and following contraction. The results suggest that input from cutaneous and deeper tissues interacts with nociceptive activity set up by the pressure stimulus. Determining the degree of sensory modulation in muscle and skin in different chronic pain syndromes could become a functional method of patient assessment important for differential diagnosis, treatment evaluation, and follow‐up.

Pain Assessment with Different Intensity Scales in Response to Loading of Joint Structures.

&NA; The purpose of the present study was to compare intensity levels assessed on Borgs Category Scale for Ratings of Perceived Pain (BRPP) (1982) (a verbal scale using adjectives and adverbs combined with the numbers 0–10), with assessments on the Visual Analogue Scale (VAS) (a 10 cm horizontal line). Eight healthy subjects volunteered in an experimental study, where pain was provoked by load on passive soft tissue elbow joint structures. Each subject participated 4 times on different occasions in the same experimental set‐up, which was divided into six 2 min periods; 3 periods with load induced by applied external weights causing load moments of 3.4 Nm, 4.5 Nm and 6.8 Nm plus that induced by the weight of the lower arm and hand (average 2.9 Nm), followed by 3 periods without external weights. Each series consisted of 12 assessments given during the last 10 sec period of each minute on either the BRPP or the VAS. No significant difference was found between the first and second time a scale was used by the same subject and none between the assessments on the VAS and the BRPP. Intensity levels of pain increased with load and time and decreased after reduction of the load moments. It is concluded that both scales can be used to reliably assess intensity levels of perceived pain elicited by loading joint structures. Intensity levels, as assessed on both scales, are associated with applied external load and time for exposure.

'A constant struggle' : successful strategies of women in work despite fibromyalgia.

Purpose. This study aimed to explore, and obtain increased knowledge of, the strategies used by working women with fibromyalgia regarding control of pain, fatigue and other symptoms. Method. Qualitative methods with an emergent design were used. The informants were women with fibromyalgia who had participated in rehabilitation 6–8 years earlier, and were still in work. Diaries, focus groups and individual interviews were used for data collection. Content analysis and grounded theory were used for the analyses. Results. A model with three categories emerged. The core category ‘constant struggle’ contains eight sub-categories: enjoying life, taking care of oneself, positive thinking, setting limits, using pain as a guide, creative solutions, learning/being knowledgeable and ‘walking a tightrope’. The category ‘grieving process’ was a prerequisite for managing the struggle and the category ‘social support’ contained what facilitated the struggle. Conclusion. The informants fought a constant struggle against the symptoms and the consequences of their fibromyalgia. Their strategies were action-oriented and evinced a positive spirit. To have grieved and accepted their situation was a prerequisite for managing, and support from the family was a help in the struggle.

Power output and work in different muscle groups during ergometer cycling.

SummaryThe aim of this study was to calculate the magnitude of the instantaneous muscular power output at the hip, knee and ankle joints during ergometer cycling. Six healthy subjects pedalled a weight-braked bicycle ergometer at 120 watts (W) and 60 revolutions per minute (rpm). The subjects were filmed with a cine camera, and pedal reaction forces were recorded from a force transducer mounted in the pedal. The muscular work at the hip, knee and ankle joint was calculated using a model based upon dynamic mechanics described elsewhere. The mean peak concentric power output was, for the hip extensors, 74.4 W, hip flexors, 18.0 W, knee extensors, 110.1 W, knee flexors, 30.0 W and ankle plantar flexors, 59.4 W. At the ankle joint, energy absorption through eccentric plantar flexor action was observed, with a mean peak power of 11.4 W and negative work of 3.4 J for each limb and complete pedal revolution. The energy production relationships between the different major muscle groups were computed and the contributions to the total positive work were: hip extensors, 27%; hip flexors, 4%; knee extensors, 39%; knee flexors, 10%; and ankle plantar flexors 20%.