Ann Bengtsson

Pain Analysis in Patients with Fibromyalgia: Effects of intravenous morphine, lidocaine, and ketamine

Pain intensity, muscle strength, static muscle endurance, pressure pain threshold, and pain tolerance at tender points and control points were assessed in 31 patients with fibromyalgia (FM), before and after intravenous administration of morphine (9 patients), lidocaine (11 patients), and ketamine (11 patients). The three different studies were double-blind and placebo-controlled. The patients were classified as placebo-responders, responders (decrease in pain intensity by > 50%) and non-responders. The morphine test did not show any significant changes. The lidocaine test showed a pain decrease during and after the infusion. The ketamine test showed a significant reduction in pain intensity during and after the test period. Tenderness at tender points decreased and endurance increased significantly, while muscle strength remained unchanged. The present results support the hypothesis that the NMDA receptors are involved in pain mechanisms in fibromyalgia. These findings also suggest that central sensitization is present in FM and that tender points represent secondary hyperalgesia.

Muscle tissue oxygen pressure in primary fibromyalgia.

Trigger points in painful muscle are a characteristic sign in patients with primary fibromyalgia. The MDO oxygen electrode was used to evaluate oxygenation in the subcutaneous tissue and in trigger points in the trapezius and brachioradial muscles. Ten patients and 8 normal controls were studied. The results in the patients were abnormal, with scattered or slalom-slope histograms, indicating low tissue oxygenation. The controls were normal, except in one case. The conclusion is that in patients with primary fibromyalgia, the muscle oxygenation is abnormal or low, at least in the trigger point area of the muscles.

Primary Fibromyalgia: A Clinical and Laboratory Study of 55 Patients

The clinical symptoms of 55 patients with primary fibromyalgia (PF) were studied and compared with 30 patients with rheumatoid arthritis (RA). The PF patients expressed a more intense feeling of illness than did the RA patients. Stiffness occurred just as often in PF as in RA. Trigger points occurred less frequently in RA patients. Muscular fatigue appeared to be one of the most disabling symptoms in PF. Neurophysiological studies indicated that the fatigue was at least partly of central origin. Ischemic forearm exercise test gave no evidence of impaired glycogenolysis. Laboratory investigation revealed normal 25-hydroxyvitamin D, cobalamin, folate, estrogen, testosterone, and myoglobin in the PF patients.

Chronic widespread musculoskeletal pain - a comparison of those who meet criteria for fibromyalgia and those who do not.

Fibromyalgia is currently classified as chronic widespread pain with widespread allodynia to pressure pain. There are few data describing pain characteristics, quality of life, consequences for daily living, and psychosocial status in patients who meet the classification criteria for fibromyalgia proposed by the American College of Rheumatology compared with patients with chronic widespread pain but not widespread allodynia.

Quantitative EMG and muscle tension in painful muscles in fibromyalgia.

&NA; Examinations were performed in 22 female fibromyalgic patients and in 9 healthy controls. The biceps brachii, trapezius, and tibial anterior muscles were examined electromyographically. The changes found were minor and non‐specific. This implies that there is no important loss of motor units and no conspicuous muscle fiber degeneration in fibromyalgia. Our investigation also failed to demonstrate any electrically detectable muscle activity in muscles where the patients during the examination reported pain (paraspinal, trapezius and tibial anterior muscles). This means that muscle tension cannot be a prominent pathogenetic factor in fibromyalgia and that factors other than muscle tension are responsible for maintaining the pain in fibromyalgia.

Prevalence of widespread pain and associations with work status: a population study

BackgroundThis population study based on a representative sample from a Swedish county investigates the prevalence, duration, and determinants of widespread pain (WSP) in the population using two constructs and estimates how WSP affects work status. In addition, this study investigates the prevalence of widespread pain and its relationship to pain intensity, gender, age, income, work status, citizenship, civil status, urban residence, and health care seeking.MethodsA cross-sectional survey using a postal questionnaire was sent to a representative sample (n = 9952) of the target population (284,073 people, 18–74 years) in a county (Östergötland) in the southern Sweden. The questionnaire was mailed and followed by two postal reminders when necessary.ResultsThe participation rate was 76.7% (n = 7637); the non-participants were on the average younger, earned less money, and male. Women had higher prevalences of pain in 10 different predetermined anatomical regions. WSP was generally chronic (90–94%) and depending on definition of WSP the prevalence varied between 4.8–7.4% in the population. Women had significantly higher prevalence of WSP than men and the age effect appeared to be stronger in women than in men. WSP was a significant negative factor – together with age 50–64 years, low annual income, and non-Nordic citizen – for work status in the community and in the group with chronic pain. Chronic pain but not the spreading of pain was related to health care seeking in the population.ConclusionThis study confirms earlier studies that report high prevalences of widespread pain in the population and especially among females and with increasing age. Widespread pain is associated with prominent effects on work status.

Diagnostic epidural opioid blockade in primary fibromyalgia at rest and during exercise

&NA; Nine patients with primary fibromyalgia participated. The patients were studied prior to, during and immediately after 4 identical periods of exercise (bicycle ergometer) each performed 30 min after injection with saline, repeated saline, an opioid and naloxone. All substances were given epidurally, except for naloxone which was given intravenously. Finally, with the patients resting in bed, lignocaine was injected epidurally. Physiological variables, general exertion, dyspnoea, lower extremity exhaustion, pain and tender points in the lower half of the body were examined. Resting pain and tender points diminished significantly after the opioid injection. Lignocaine completely abolished resting pain and tender points. Lower extremity exhaustion was reduced by the opioid. General exertion and dyspnoea were unaffected by the opioid. In conclusion the results support the hypothesis that the pain in fibromyalgia is of peripheral nociceptive or spinal origin. We raise the hypothesis that the fatigability is, at least partly, due to inhibition because of pain.

Muscle metabolism in fibromyalgia studied by P‐31 magnetic resonance spectroscopy during aerobic and anaerobic exercise

Objective: To investigate mechanisms underlying the reduced work capacity of fibromyalgia (FM) patients were compared to healthy controls at specified workloads, using P‐31 magnetic resonance spectroscopy (MRS). Methods: The forearm flexor muscle group was examined with MRS at rest, at sub maximal and at maximal controlled dynamic work as well as at maximal isometric contraction. Aerobic fitness was determined by bicycle ergonometry. Results: Metabolite concentrations and muscle pH were similar for patients and controls at lower workloads. At maximal dynamic and static contractions the concentration of inorganic phosphate was lower and at static contractions the pH decrease was smaller in patients. The performed work by patients was only 50% compared to controls and the patients experienced more pain. Maximal oxygen uptake was lower in the fibromyalgia group. Expired gas‐analysis in this group showed ventilatory equivalents at similar relative levels of maximal work capacity. Conclusion: Fibromyalgia patients seem to utilise less of the energy rich phosphorous metabolites at maximal work despite pH reduction. They seemed to be less aerobic fitted and reached the anaerobic threshold earlier than the controls.

Decreased muscle concentrations of ATP and PCR in the quadriceps muscle of fibromyalgia patients – A 31P-MRS study

Fibromyalgia (FMS) has a prevalence of approximately 2% in the population. Central alterations have been described in FMS, but there is not consensus with respect to the role of peripheral factors for the maintenance of FMS. 31P Magnetic Resonance Spectroscopy (31P‐MRS) has been used to investigate the metabolism of phosphagens in muscles of FMS patients, but the results in the literature are not in consensus. The aim was to investigate the quantitative content of phosphagens and pH in resting quadriceps muscle of patients with FMS (n = 19) and in healthy controls (Controls; n = 14) using 31P‐MRS. It was also investigated whether the concentrations of these substances correlated with measures of pain and/or physical capacity.

Intestinal Permeability to Different-Sized Polyethyleneglycols in Patients with Rheumatoid Arthritis

The intestinal permeability to polyethyleneglycols (PEGs) of varying size in patients with rheumatoid arthritis has been investigated. Permeability was determined by measuring the 6-hour urinary recovery of different-sized PEGs after oral intake of PEG 400, PEG 1000, or PEG 3000. Patients with rheumatoid arthritis excreted significantly less PEG 400 and PEG 1000 than healthy individuals, whereas the excretion of PEG 3000 was the same or even greater than in healthy individuals. These findings point to the possibility that intestinal permeability is altered in rheumatoid arthritis.