MR imaging of muscle and tender points in fibromyalgia

Ultrasonographic evaluation of muscle thickness in female patients with fibromyalgia and its relationship with clinical parameters

OBJECTIVE

The aim of this study was to compare the ultrasonographic thickness of selected major muscles of patients with fibromyalgia syndrome (FMS) and asymptomatic control subjects and to evaluate the relationship between muscle thickness and muscle strength, physical performance, kinesiophobia, and clinical variables.

METHODS

Twenty-two FMS patients and 18 asymptomatic control cases who applied to the physical medicine and rehabilitation outpatient clinic were included. The thickness of the gastrocnemius medialis/lateralis, trapezius, and upper arm muscle was evaluated with ultrasonography. Muscle strength was evaluated with hand grip strength, muscle performance with chair stand test (CST), walking performance with 10 m walking test, disease severity with Fibromyalgia Impact Questionnaire-Revised, pain severity with VAS, and kinesiophobia with TAMPA kinesiophobia scale.

RESULTS

The mean thickness values of all the muscles measured were significantly decreased in the FMS group compared with the control (p<0.05). There were positive correlations between gastrocnemius medialis/lateralis and upper arm muscle thickness with hand grip strength (p<0.01, r=0.602, r=0.663, r=0.567, respectively) and positive correlations between gastrocnemius medialis/lateralis muscle thickness with CST (p<0.05, r=0.507, r=0.512, respectively). TAMPA was significantly negatively correlated with gastrocnemius medialis/lateralis and upper arm muscle thickness.

CONCLUSION

Muscle thickness, strength, and performance decrease in FMS patients. This reduction in muscle strength, performance, and size is associated with kinesiophobia. Strengthening exercises should be included in the management of FMS patients. However, caution should be exercised when prescribing exercises that require extreme muscle performance, considering that it may cause kinesiophobia.

Machine Learning Diagnostic Modeling for Classifying Fibromyalgia Using B-mode Ultrasound Images

Fibromyalgia (FM) diagnosis remains a challenge for clinicians due to a lack of objective diagnostic tools. One proposed solution is the use of quantitative ultrasound (US) techniques, such as image texture analysis, which has demonstrated discriminatory capabilities with other chronic pain conditions. From this, we propose the use of image texture variables to construct and compare two machine learning models (support vector machine [SVM] and logistic regression) for differentiating between the trapezius muscle in healthy and FM patients. US videos of the right and left trapezius muscle were acquired from healthy (n = 51) participants and those with FM (n = 57). The videos were converted into 64,800 skeletal muscle regions of interest (ROIs) using MATLAB. The ROIs were filtered by an algorithm using the complex wavelet structural similarity index (CW-SSIM), which removed ROIs that were similar. Thirty-one texture variables were extracted from the ROIs, which were then used in nested cross-validation to construct SVM and elastic net regularized logistic regression models. The generalized performance accuracy of both models was estimated and confirmed with a final validation on a holdout test set. The predicted generalized performance accuracy of the SVM and logistic regression models was computed to be 83.9 ± 2.6% and 65.8 ± 1.7%, respectively. The models achieved accuracies of 84.1%, and 66.0% on the final holdout test set, validating performance estimates. Although both machine learning models differentiate between healthy trapezius muscle and that of patients with FM, only the SVM model demonstrated clinically relevant performance levels.

Spondyloarthropathy with entheseal pain. A prospective study in 33 patients

OBJECTIVES

To identify objective features individualizing spondyloarthropathy with isolated entheseal pain and distinguishing this condition from fibromyalgia.

PATIENTS AND METHODS

Thirty-three patients presenting with entheseal pain were studied prospectively. The diagnoses were psoriatic arthritis in six patients and ankylosing spondylitis in seven patients; among the 20 remaining patients, in whom entheseal pain was the only symptom, 11 responded to nonsteroidal antiinflammatory drugs (NSAIDs) and were diagnosed with entheseal spondyloarthropathy whereas the nine unresponsive patients were diagnosed with fibromyalgia. A physical examination, laboratory tests, plain radiographs, and radionuclide scan and resonance imaging (MRI) scan of a painful enthesis were done in each patient.

RESULTS

Among the 11 patients with entheseal spondyloarthropathy, two experienced inflammatory joint symptoms during the 4-6-month follow-up and three patients had radionuclide scanning and MRI evidence of entheseal inflammation similar to that in nine patients with definite spondyloarthropathy (ankylosing spondylitis or psoriatic arthritis). The feature that best discriminated between entheseal spondyloarthropathy and fibromyalgia was responsiveness to NSAIDs.

CONCLUSION

These preliminary data suggest that isolated entheseal pain may indicate spondyloarthropathy in some patients. The imaging methods used in this study lacked sensitivity for enthesitis, which may therefore have been missed in some patients. The development of bone and joint ultrasonography may provide additional insights into the entheseal abnormalities present in patients with isolated entheseal pain.

Botulinum toxins in pain management

BTs are a useful treatment in refractory MPS and have shown promise in various superficial neuropathic pain syndromes. Presumably BTs work by breaking the spasm/pain cycle, giving the patient a "window of opportunity" for traditional conservative measures to have a greater beneficial impact, but several studies suggest that a direct antinociceptive effect distinct from any reduction in muscle spasm may be at play. The major benefit of BTs compared with standard therapies is duration of response. BTs cannot be considered a "first line" treatment for any pain application; however, in refractory cases in which nothing else has helped, BTs may offer the patient and physician a chance for improvement and perhaps even cure.

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.

Is there muscle pathology in fibromyalgia syndrome?

A number of studies have reported abnormalities in the muscles of fibromyalgia patients. The early studies, some of which indicated morphologic abnormalities, had major problems with patient selection and lacked adequate control groups. More recent studies of morphology have shown only nonspecific or mild changes, perhaps consistent with subtle metabolic abnormalities, especially at tender point sites. Studies of muscle metabolism, however, particularly the more rigorous studies using MR spectroscopy, have failed to confirm abnormalities in muscle metabolism, both at tender and nontender point locations. The abnormalities detected in earlier studies appear to have been confounded by subtle metabolic changes resulting from muscle deconditioning. Studies of muscle blood flow also demonstrate abnormalities that can be explained by deconditioning alone. Studies of muscle strength that show differences between patients and controls can be explained by lack of voluntary effort. A popular theory of the genesis of pain in fibromyalgia syndrome was that excessive muscle tension led to increased excitability of nociceptors in muscle leading to muscle hypertension and chronic pain. Furthermore, defective sympathetic control was proposed to result in disturbed microcirculation and nociceptor excitation. In aggregate, however, studies using EMG techniques show no evidence of excessive muscle tension or defective sympathetic nervous function. Therefore, although muscular pain has been a central feature of fibromyalgia syndrome, controlled studies of muscle fail to support a convincing role for muscle in the pathophysiology of the condition. Muscle tenderness in fibromyalgia cannot be explained on the basis of primary muscle abnormalities, either structural or functional. Future pathophysiologic studies in fibromyalgia should focus on central mechanisms.

Neurobiology of the myofascial trigger point

The clinical phenomenon of the MTrP is accessible to any clinician who takes the time to learn to palpate skeletal muscle gently and carefully, and who is willing to learn the functional anatomy necessary to understand the regional spread of MTrPs through functional muscle units (Travell and Simons, 1992). Yet despite the years of clinical study of MPS, the pathophysiology of the central feature, the trigger point, has remained elusive. Many investigators have contributed to the general understanding of the mechanisms of pain perception, but we owe a particular debt of gratitude to Dr Seigfried Mense of Heidelberg for his pursuit of the study of pain originating in muscle lesions. However, Dr Mense would be the first to caution us against the direct transference of the results obtained with an inflammatory lesion produced in the experimental animal to the pain of MTrPs in the clinic patient. Notwithstanding that, researchers in the field of pain have given us an understanding of the basis for the hyperalgesia, allodynia and the previously difficult-to-understand finding of referred pain zones that we see daily in our patients. Finally, the interesting initial observations of Hubbard and Berkoff (1993), suggesting that the muscle spindle may be associated with the trigger point, open yet another door in our understanding of the nature of MPS.