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Muscle involvement in juvenile idiopathic arthritis
Linköping University, Department of Neuroscience and Locomotion. Linköping University, Department of Clinical and Experimental Medicine, Clinical Neurophysiology . Östergötlands Läns Landsting, Reconstruction Centre, Department of Neurophysiology UHL.
Linköping University, Department of Clinical and Experimental Medicine, Neurology . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Local Health Care Services in Central Östergötland, Department of Neurology.
2004 (English)In: Rheumatology, ISSN 1462-0324 (print) 1462-0332 (online), Vol. 43, no 12, 1546-1554 p.Article in journal (Refereed) Published
Abstract [en]

OBJECTIVE: An observational study of changes in muscle structure and the relation to muscle strength in juvenile idiopathic arthritis (JIA).

METHODS: Fifteen children and teenagers (eight girls and seven boys) with JIA, aged 9-19 yr (mean age 16.1), were studied. Muscle biopsies were obtained from the anterior tibial muscle and were examined using histopathological and immunohistochemical methods. Muscle fibre types were classified and fibre areas measured. As markers of inflammation, the major histocompatibility complex (MHC) class I and class II and the membrane attack complex (MAC) were analysed. Results were compared with biopsies from the gastrocnemius muscle in 33 young (19-23 yr) healthy controls. Isometric and isokinetic muscle strengths were measured in ankle dorsiflexion. Strength was compared with reference values for healthy age-matched controls. Nerve conduction velocities were recorded in the peroneal and sural nerves.

RESULTS: Four of the 15 muscle biopsies were morphologically normal. Eleven biopsies showed minor unspecific changes. Two of these also showed minor signs of inflammation. MHC class II expression was found in 4/15 patients, which was significantly more than in the healthy controls (P = 0.0143). The expression of MHC class I and MAC did not differ from that in the controls. The mean area of type I fibres was lower than that of type IIA fibres in 12/13 biopsies. Muscle strength was significantly reduced in the patient group. There was a significant positive correlation between muscle fibre area and muscle strength. Nerve conduction studies were normal in all cases.

CONCLUSIONS: Changes in leg muscle biopsies appear to be common in children and teenagers with JIA. The presence of inflammatory cells in the muscle and expression of MHC class II on muscle fibres may be a sign of inflammatory myopathy. There are no findings of type II muscle fibre hypotrophy or neuropathy, as in adults with RA.

Place, publisher, year, edition, pages
2004. Vol. 43, no 12, 1546-1554 p.
National Category
Medical and Health Sciences
URN: urn:nbn:se:liu:diva-13647DOI: 10.1093/rheumatology/keh381OAI: diva2:21107
Available from: 2004-05-27 Created: 2004-05-27 Last updated: 2009-08-19
In thesis
1. Muscle function in Juvenile Idiopathic Arthritis: A two-year follow-up
Open this publication in new window or tab >>Muscle function in Juvenile Idiopathic Arthritis: A two-year follow-up
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This is a study of muscle function in Juvenile Idiopathic Arthritis (JIA). Rheumatoid arthritis (RA) is a disease that primarily affects the synovial membrane of joints. Muscle weakness, atrophy and pain occur in adult RA. This may be a consequence of joint pain, stiffness and immobility. Muscle inflammation and neuropathy occur as complications in adults. Muscle function in JIA has been much less studied.

The aim of the study was to examine whether muscle weakness and atrophy also occur in children with JIA.

This was a longitudinal study over a two-year period, where muscle strength and thickness were measured repeatedly in a group of 20 children and teenagers with JIA. Muscle strength was measured using different methods and in several muscle groups. Muscle biopsies were obtained and nerve conduction velocity studies performed.

The study concludes that, compared to healthy people, children and teenagers with JIA have as a group reduced muscle strength and muscle thickness. For most of these children and teenagers, muscle strength is only slightly lower than expected, but a few have marked muscle weakness. This is most apparent in patients with severe polyarthritis where the weakness seems to be widespread. Patients with isolated arthritis may also have greatly reduced strength and thickness of muscles near the inflamed joint.

There is a risk of decreasing strength in patients with polyarthritis and in muscles near an active arthritis.

Minor changes are common in muscle biopsies, and findings may indicate immunological activity in the muscles.

Atrophy of type II fibres, as in adult RA, was not found in JIA.

No patient had signs of neuropathy.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2004. 97 p.
Linköping University Medical Dissertations, ISSN 0345-0082 ; 847
arthritis, juvenile rheumatoid, physiopathology, muscle, skeletal, pathology, physiopathology, Muscular atrophy, etiology, physiopathology, arthritis, juvenile rheumatoid, complications
National Category
Clinical Science
urn:nbn:se:liu:diva-5195 (URN)91-7373-819-0 (ISBN)
Public defence
2004-05-07, Viktoriasalen, Campus US, Linköpings universitet, Linköping, 13:00 (English)
On the day of the public defence the status of article IV was: Submitted.Available from: 2004-05-27 Created: 2004-05-27 Last updated: 2012-01-25Bibliographically approved

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Lindehammar, HansLindvall, Björn
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Department of Neuroscience and LocomotionClinical Neurophysiology Department of Neurophysiology UHLNeurology Faculty of Health SciencesDepartment of Neurology
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