Is the tender point concept valid?

Gender differences in pressure pain threshold in a repeated measures assessment

The objective of this study was to evaluate gender differences in the pain threshold, considering the type of pressure point, its location and the repetition of the assessment. The pressure pain threshold was evaluated in 30 healthy volunteers (12 men and 18 women) in three assessment sessions separated by 15 min and 7 days, respectively. Each assessment session was in turn composed of two trials in each of which 24 different pressure points (symmetrically located), representing the 18 tender points for the diagnosis of fibromyalgia and six control points, were assessed. Gender differences were found in the pain threshold for all of the points and the measures taken, women showing a lower pain threshold in comparison to men and being these differences more pronounced for control points than for tender points, the former reaching statistical significance in all cases. The analysis of the influence of repeated measures on gender differences in the pain threshold showed a distinct pattern of recuperation in men than in women, although only one difference in pain threshold was significant. The utility of the tender point concept to study gender differences in pain threshold and the mechanisms that may explain different patterns of recuperation between genders are discussed.

[Clinical evaluation of fibromyalgia]

OBJECTIVES

Fibromyalgia is characterized by diffuse, persistent and unexplained muscle pain associated with tenderness (mechanical allodynia) and unspecific symptoms. Diagnosis criteria as well as pathophysiological mechanisms are still unclear, justifying appropriate questionnaires and clinical investigations.

ACTUAL TOPICS

Several questionnaires including visual analogic scales with respect to pain, fatigue, sleep or mood disorders have been used in fibromyalgia such as Fibromyalgia Impact Questionnaire (30 items) and the European List for Fibromyalgia Evaluation (53 items). Similarly several methods have been proposed to evaluate tenderness in fibromyalgia patients: The study of tender points involves their number (normal value < 4/18), or their pain mean intensity score and the sum of their sensitivities defining the tender point index (normal value < 11/72); The average pain threshold (normal value > 4 kg/cm(2)) is more precise, requiring sophisticated devices (mechanical algometers) and physician training; Less complex than pain threshold measurement, more reliable than the tender points number or index, the tensiometer induced myalgia (normal value > 210 mmHg) is probably a promising new alternative way to screen for fibromyalgia.

PROSPECTS

Even if further studies are needed, diagnosis approach of fibromyalgia could be improved by new tools such as the European List for Fibromyalgia Evaluation and algotensiometry.

Trigger points and tender points: one and the same? Does injection treatment help?

Trigger points are defined as areas of muscle that are painful to palpation and are characterized by the presence of taut bands and the generation of a referral pattern of pain. Tender points are areas of tenderness occurring in muscle, muscle-tendon junction, bursa, or fat pad. When tender points occur in a widespread manner, they are usually considered characteristic of fibromyalgia. Trigger points, which typically occur in a more restricted regional pattern, are indicative of myofascial pain syndrome. In some patients the two phenomena may coexists, and overlap syndromes can occur. Although experienced examiners can generally identify the same tender points, interrater reliability of trigger points has been low in most studies. There is continued controversy regarding the defining characteristics and homogeneity of myofascial pain because of the variability of the examination findings. In appropriately selected patients, it appears that myofascial trigger point injections can be helpful in decreasing pain and improving range of motion in conjunction with a comprehensive exercise and rehabilitation program.

Are tender point scores assessed by manual palpation in fibromyalgia reliable? An investigation into the variance of tender point scores

To determine the reliability of tender point assessment by manual palpation in patients with fibromyalgia, and to investigate the sources of variance, tender point scores by manual palpation were obtained in 30 fibromyalgia patients by 2 investigators; the assessments were repeated after 1 week. Test-retest stability and inter-observer agreement of tender point scores was moderate to high. The most important sources of variance were inter-individual patient differences in (1) mean tenderness (pain thresholds) and (2) tender point profiles (consistent intra-individual differences between the 14 tender point scores), and (3) residual variance, not attributable to any systematic effect (error). It is concluded that the reliability of tender point assessment by manual palpation is acceptable. It seems to be not less than reliability of assessment by pressure algometer. Tender point scores in fibromyalgia reflect individual differences in mean pain thresholds as well as individual tender point profiles.

Effect of zopiclone on sleep quality, morning stiffness, widespread tenderness and pain and general discomfort in primary fibromyalgia patients. A double-blind randomized trial

Thirty-three patients fulfilling the diagnostic criteria for primary fibromyalgia completed an eight-week double-blind treatment trial with the drug zopiclone. Of outcome measures studied a score expressing subjective sleep quality showed improvement in more than ninety percent of zopiclone patients at 4 weeks and nearly eighty percent at 8 weeks, but similar improvement was also reported by more than sixty percent of the patients on placebo. Patient self-assessment of a treatment effect also showed an advantage for zopiclone, with most patients in the placebo group considering their state as unchanged at 8 weeks. According to examiner assessment, however, half the patients in both groups showed improvement at 8 weeks. For other assessment variables, e.g. dolorimeter assessment of widespread tenderness, visual analogue scales and pain drawings for pain and other subjective feelings of discomfort, the effects of zopiclone treatment were at the same level as those of placebo.

Pressure pain threshold in pain-free subjects, in patients with chronic regional pain syndromes, and in patients with fibromyalgia syndrome

OBJECTIVE

We hypothesized that change in pain threshold to pressure reflects a generalized change in the pain system affecting both tender and control points.

METHODS

We assessed 18 tender points and 4 control points using an algometer in 60 patients with generalized fibromyalgia/fibrositis syndrome, 60 patients with localized chronic pain syndromes, and in 60 pain-free subjects.

RESULTS

A significant correlation was found between myalgia scores at tender points and control points in these subjects.

CONCLUSION

These results suggest that there is a diffuse change in pain modulation in fibromyalgia, as hypothesized, but the tender point is still clinically useful.

Fibromyalgia syndrome

Fibromyalgia is a chronic rheumatologic disorder. The primary symptoms include musculoskeletal pain and aching, disturbed sleep, fatigue, morning stiffness, and local tenderness. It is frequently misdiagnosed, despite being a fairly common, chronic disorder in most primary care clinics. Failure to make this diagnosis often leads to unnecessary medical and surgical treatment. The treatment of fibromyalgia syndrome is multifaceted. Goals include reassurance, education about pain management and modification, and symptom reduction. Exercise may be beneficial. Amitriptyline is effective in reducing certain symptoms of fibromyalgia, such as pain and lack of restful sleep. Narcotics, steroids, and nonsteroidal anti-inflammatory drugs (NSAIDs) should be avoided.

Tenderness in 75 anatomic sites. Distinguishing fibromyalgia patients from controls

We studied tenderness at 75 unilateral anatomic locations in 10 fibromyalgia patients and 10 normal control subjects to determine which sites best identified patients with fibromyalgia. Using a dolorimeter, the mean amount of pressure required to elicit tenderness was significantly lower in patients than in controls at 19 sites (P less than 0.001). Of the previously proposed tender points, only 2 were included in those 19 best discriminating points. Fifteen of the 19 best discriminating points were clustered in regions around the anterior shoulder, anterior chest, posterior scapula, and medial knee. The 19 sites that we have identified best separate patients with fibromyalgia from controls, although the discriminating power of these sites in other chronic pain syndromes will require further study. Examination of specific regions may be more useful clinically than the exact anatomic sites within these regions.

Development of criteria for the diagnosis of fibrositis

The essential symptoms of fibrositis--widespread aching and pain, disturbed sleep, morning stiffness, and fatigue--are common in both rheumatic and nonrheumatic patients. But the essential sign of fibrositis--widespread local tenderness over specific anatomic sites ("tender points")--is rare in any patients except those with fibrositis. Clinical criteria for the diagnosis of fibrositis rely heavily on a high tender point count in the presence of characteristic fibrositic symptoms. Multiple tender points are uncommon in normal subjects and in those with rheumatic and nonrheumatic disorders. The tender point count thus also serves to distinguish fibrositis from other musculoskeletal diseases.