Comparative analyses of muscle MRI and muscular function in anti-synthetase syndrome patients and matched controls: a cross-sectional study.

BACKGROUND: Magnetic resonance imaging (MRI) of thigh muscles is increasingly used to assess disease activity and damage extent in chronic myositis, but the validity of the findings is not clear. Here, the primary aim was to compare thigh MRI findings in patients having chronic myositis associated with anti-synthetase syndrome (ASS) and in matched healthy controls. METHODS: Cross-sectional analyses of thigh muscle MRI, muscular function and creatinine kinase (CK) were performed in 68 ASS patients (median disease duration 71 months) and 67 controls matched for age and gender. MRI changes associated with disease activity (edema in muscles and fascia) and damage (fatty replacement and muscle volume reduction) were assessed semiquantitatively, giving a total MRI score of 0-78 (total edema 0-42 and total damage 0-36). RESULTS: ASS patients had higher total MRI score than the matched controls (14.1 versus 3.0; p < 0.001) and less muscle strength (p < 0.001). Muscle edema was more frequent in ASS patients than controls (38% versus 12%), as was fatty replacement (42% versus 4%). In ASS patients, we found that the total edema score correlated with CK, but 23% of the patients with normal CK had score > 18. Muscle compartment analyses in ASS patients showed that muscle edema was most pronounced anteriorly, while fatty replacement dominated posteriorly. CONCLUSIONS: This study showed, for the first time, the magnitude of difference in muscle MRI findings between chronic myositis cases and matched controls. In ASS patients, muscle MRI appeared to provide useful complementary information to muscle strength and CK levels in the assessment of myositis.

Long-term experience with rituximab in anti-synthetase syndrome-related interstitial lung disease.

OBJECTIVE: To retrospectively evaluate the efficacy and safety of rituximab (Rtx) treatment in patients with anti-synthetase syndrome (ASS) and severe interstitial lung disease (ILD). METHODS: Patients with severe ILD and >12 months follow-up post-Rtx were identified from the Oslo University Hospital ASS cohort (n = 112). Clinical data, including pulmonary function tests (PFTs), were retrospectively collected from medical reports. Extent of ILD pre-, and post-Rtx was scored on thin-section high-resolution CT (HRCT) images and expressed as a percentage of total lung volume. Muscle strength was evaluated by manual muscle testing of eight muscle groups (MMT8). RESULTS: Altogether, 34/112 ASS patients had received Rtx; 24/34 had severe ILD and >12 months follow-up post-Rtx (median 52 months). In these 24 patients, the median percentage of predicted forced vital capacity, forced expiratory volume in 1 s (FEV1) and diffusing capacity of the lungs for carbon monoxide (DLCO) increased by 24%, 22% and 17%, respectively, post-Rtx. Seven patients (all with disease duration <12 months and/or acute onset/exacerbation of ILD) had >30% improvement in all three PFTs. HRCT analysis showed a median 34% reduction in ILD extent post-Rtx. MMT8 score increased post-Rtx. During follow-up, 7/34 (21%) Rtx-treated ASS patients died; 6/7 deaths were related to infections. The mortality rate in the Rtx-treated group was comparable to that of the remaining ASS cohort (25/78 deceased; 32%). CONCLUSION: This study, which included 24 Rtx-treated ASS patients with severe ILD, reports improved PFTs after a median 52 months follow-up post-Rtx. The best outcome was observed in patients with a disease duration <12 months and/or acute onset/exacerbation of ILD. The study indicates that Rtx could be a treatment option for selected ASS patients, but infections should be given attention.

Long-term follow-up of sporadic inclusion body myositis treated with intravenous immunoglobulin: a retrospective study of 16 patients.

OBJECTIVES: Previous studies of intravenous immunoglobulin (IVIG) treatment in sporadic inclusion body myositis (sIBM) have yielded conflicting results. Here, we have undertaken a retrospective assessment of the long-term effects of IVIG in our sIBM cohort. METHODS: Sixteen sIBM patients, treated with a mean of 10 IVIG infusions and followed up for a mean period of 23 months, were identified. Six sIBM patients treated with other drugs were used as an internal control group. Serial data on manual muscle testing (MMT), laboratory parameters and patients' subjective assessment were collected. RESULTS: Serial MMT scores were available in 14 IVIG treated patients. Two of these patients improved more than 20% in MMT from baseline up to the third IVIG infusion. One of six patients in the control group showed a similar MMT improvement during the first six months. Improved swallowing function was reported by three IVIG-treated patients, but none of the controls. The serum levels of creatine kinase fell more than 20 % after the first IVIG infusion in 7/16 IVIG-treated patients, but this improvement was not sustained during the follow-up period. CONCLUSIONS: IVIG treatment appears to have short-term beneficial effects on muscle strength and dysphagia in some few sIBM patients, but these effects are not sustained over time.