Background Inflammatory myopathies (IM) comprise a group of rare and heterogeneous diseases, challenging to diagnose, treat and follow-up. Monitoring patients with IM is difficult as there is a lack of precise measures for assessing disease activity. Ultrasonography (US) is a non-invasive, relatively inexpensive technique that is increasingly being used to evaluate muscular system.
Objectives To assess the utility of US evaluation in the monitoring of patients with IM.
Methods Patients diagnosed of IM from 2005 to 2015 followed up at a Rheumatology Department were included. Fourteen patients (11 female) with a mean age of 50.1±21.4 years and mean disease duration of 4.8±3.2 years were evaluated. The different diagnosis were as follows: 6 dermatomyositis (DM), 3 polymyositis (PM), 2 myositis associated with Systemic Lupus Erythematosus, 1 inclusion body myositis (IBM), 1 recurrent focal myositis (RFM) and 1 undifferentiated IM. Physical examination, including muscle strength tests, laboratorial tests (comprising levels of serum muscle enzymes) and a selective muscle US assessment were performed to each patient. For US evaluation a General Electric LOGIQ S8 equipment with a 6–15 MHz linear transducer was used. Muscles were subjectively evaluated for echogenicity (determined by gray-scale) and muscle morphology. Power Doppler (PD) was used to assess vascularity.
Results Nine of the 14 patients evaluated were on clinical remission, with absence of symptoms or signs of disease, preserved muscle strength, normal muscle enzyme levels and conserved muscle pattern on US assessment. One female with DM presented with an acute exacerbation of disease, with proximal muscular weakness of the upper limb and US findings of increased muscle echogenicity of biceps revealing a muscle oedema pattern. The patient with IBM also experienced a flare which was associated with proximal muscle weakness and asthenia; US assessment showed focal oedema through right biceps muscle but also proximal lower limb muscle atrophy characterized by increased echogenicity with diminished volume of the quadriceps compartment and change of normal architecture of tibialis anterior muscle of both legs. These findings are consistent with a long term disease with acute flare. Another patient with longstanding PM in remission revealed no signs or symptoms of active disease, normal muscle strength but low creatine phosphokinase levels and symmetrical proximal muscle atrophy pattern in US evaluation. On the other hand, the patient with shorter duration of disease, recently diagnosed as myositis (undifferentiated IM), revealed proximal weakness and elevated serum muscle enzymes; in this case, US assessment showed diffuse increased echogenicity of proximal muscle compartment and increased PD signal. Finally, the patient with RFM presented with left arm swelling and weakness and US evaluation showed enlargement and diffuse increased echogenicity within the left carpal extensor compartment.
Conclusions US findings in patients with IM seem to correlate well with disease activity suggested by clinical and laboratory data. As a result, US imaging may be a useful tool to assess disease activity and damage in these patients as well as to monitor disease progression.
Adler RS and Garofalo G. Ultrasound in the evaluation of the inflammatory myopathies. Curr Rheumatol reports. 2009. 11:302–308.
Disclosure of Interest None declared