Muscle strength assessment in polymyositis and dermatomyositis evaluation of the reliability and clinical use of a new, quantitative, easily applicable method

OBJECTIVE

To evaluate the feasibility and the reliability of a quantitative method of maximal isometric strength measurement for the assessment of patients with myositis in clinical practice and research.

METHODS

Three observers independently examined the strength of 13 muscle groups of 7 patients with stable polymyositis and dermatomyositis (PM/DM) using a handheld pull-gauge. Reliability was assessed following a balanced random 3-way cross classification with interactions and using the analysis of variance method. Serial followup strength data for 2 patients were compared to change in creatinine kinase (CK) levels.

RESULTS

All measurements could be performed without causing pain to the patients. One single test including 13 muscle groups was done in 7 min or less. Both intra and interobserver correlations were strong and significant for all muscle groups. The intraobserver reliability ranged from 0.88 for elbow extensors to 0.98 for knee extensors and cervical spine flexors. The interobserver reliability ranged from 0.81 for elbow flexors to 0.98 for knee extensors and cervical spine flexors. The followup of 2 cases yielded moderate to strong correlations of serial strength measurements with CK levels.

CONCLUSION

Serial measurement of isometric muscle strength with a handheld pull-gauge is a feasible, inexpensive, time efficient and reliable method and may provide additional quantitative information in the clinical assessment of patients with myositis.

[Parvovirus B19-induced arthritis/arthropathy--an important differential diagnosis of chronic polyarthritis]

INTRODUCTION/AIMS

The differential diagnosis of rheumatoid arthritis (RA) and parvovirus-B19-induced arthritis/arthropathy (PBA) can be difficult, but is of importance because of the different therapeutic implications. The purpose is to describe characteristic features serving to differentiate between chronic PBA and RA, based on 6 personal cases and the literature.

METHODS/PATIENTS

6 patients presenting with acute (3 cases) or chronic PBA (3 cases) over the last 5 years are described.

RESULTS/CONCLUSIONS

The demonstration of anti-parvovirus-B19-immunoglobulins (Ig)M in addition to anti-parvovirus-B19-IgG is the most important diagnostic finding. Measurement of IgM must be done within the first months after onset, as it disappears later on. Furthermore, history of disease (exposure, prodromi and acute onset of arthritis), clinical examination (rash) and further investigations (normal ESR and CRP, typical hematologic findings, examination of synovial tissue and fluid without inflammatory changes, demonstration of the genome of parvovirus B19 by polymerase chain reaction, no erosions on radiographs) support the diagnosis of PBA. 2 of the 3 patients with chronic PBA fulfilled the criteria for classification of RA. Therapeutic approaches in PBA are discussed. In contrast to the favourable effect in RA, immunosuppressive agents may prolong persistence of virus and disease in PBA.

Does a muscle strength index provide complementary information to traditional disease activity variables in patients with rheumatoid arthritis?

OBJECTIVE

To develop a muscle strength index (MSI) and determine whether it provides complementary information to traditional disease activity variables in patients with rheumatoid arthritis (RA).

METHODS

The MSI was developed on the basis of practical and empirical aspects and statistical considerations. Intra and interobserver reliability was assessed on the data from 3 observers on 2 strength measurements in each of 10 patients. The association of the MSI with variables of disease activity and severity was assessed in univariate analysis. The contribution of the MSI in the explanation of physician's global disease activity after accounting for the effect of traditional measures of disease activity was assessed in multiple linear regression models.

RESULTS

Eight strength measurements (extension and flexion of knee and elbow joints) obtained with a hand held pull gauge were aggregated into the MSI as the mean of the standardized scores. In 65 patients with RA, the MSI had a high internal consistency (Cronbach's alpha 0.95) and intra and interobserver reliability (Pearson correlation coefficient 0.94 each). The MSI correlated moderately with traditional measures of disease activity and strongly with physical functional disability and radiological damage. In contrast to grip strength, the MSI explained additional variation of physician's global assessment of disease activity if added to variables of pooled activity indices.

CONCLUSION

The MSI is a reliable and valid measure of disease activity and severity and may improve the content validity of pooled disease activity indices.

[Systemic sclerosis (scleroderma): etiology and pathogenesis--where are we today?]

Systemic sclerosis is a rare chronic disease with inflammatory and vascular features leading to increased fibrosis of skin and internal organs. The pathogenesis of systemic sclerosis and scleroderma like diseases appears to be influenced rather by environmental than by genetic factors. Clinical and pathogenetic aspects of systemic sclerosis show similarities to untreated chronic graft-versus-host-disease after bone marrow transplantation. New insights into the pathogenesis of systemic sclerosis give reason to hope that better therapeutic approaches will be developed in the future.

A simple HPLC technique for accurate monitoring of mammalian cell metabolism

We have developed a simple and accurate isocratic HPLC method, without any prederivatisation, for the determination of glucose, lactate, glutamine, glutamate, pyrrolidone carboxylic acid and alanine in samples from mammalian cell cultures. The method has been successfully validated with enzyme analysis for each of the compounds. Quantification of pyrrolidone carboxylic acid makes the correction for glutamine decrease due to chemical decomposition very simple and accurate, and avoids some possibly erroneous calculations.

IgA nephropathy and hypercalcemia in Whipple's disease

In 2 patients an IgA nephropathy was found 2 and 5 years before gastrointestinal symptoms led to the diagnosis of Whipple's disease. One patient additionally presented with hypercalcemia. Subsequently 1 patient died, whereas treatment with trimethoprim/sulfamethoxazole resulted in an improvement of IgA nephropathy and in a complete recovery from hypercalcemia and all the manifestations of Whipple's disease in the other patient. IgA nephropathy and hypercalcemia may be considered as early manifestations of Whipple's disease.

[Polymyositis: disease course and therapy with intravenously administered immunoglobulins]

Corticosteroids and immunosuppressive agents are standard treatment for polymyositis (PM) and dermatomyositis (DM) respectively. Recent reports have emphasized a potentially successful regimen with intravenous immune gammaglobulins (IVIG). The short term success of this treatment in a personally observed case is described. IVIG treatment resulted in normalization of the serum concentrations of the muscle enzymes after continued inflammatory activity under treatment with azathioprine, cyclophosphamide and methotrexate in combination with corticosteroids. The improvement of PM by IVIG was further documented by an increase in muscle strength of up to 367% of the initial value and a regression of the myositic changes in the muscles of the thighs as evidenced by magnetic resonance imaging (MRI). The therapeutic response was paralleled by reversal of peripheral lymphopenia. Experience with IVIG treatment in PM/DM is reviewed and the potential role of this regimen in the management of PM/DM is discussed.