SAT0674 The use of quantitative muscle ultrasound as a follow-up tool in inflammatory myositis and duchenne muscular dystrophy in children
Authors: W.A. Hassan, A.E.S. Elbrashy, S.S. Ganeb, D.R. Lasheen, E.A. Mohammady
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Ultrasound (US) can provide a painless and noninvasive tool for evaluation and follow up of muscle diseases especially in young children who may have restrictions in execution of muscle strength tests and functional scales. <h3>Objectives</h3> This study aimed to assess skeletal muscle structural status in children with Juvenile dermatomyositis (JDM) and Duchenne muscular dystrophy (DMD) using quantitative muscle US and to perform a longitudinal follow up of these changes over time and correlate these findings with clinical parameters, functional scales, biochemical and electromyographic tests. <h3>Methods</h3> This is a longitudinal study conducted on 35 subjects: 20 JDM patients and 15 DMD patients at baseline and after 12 months of follow-up. In all patients, Quantitative MSUS measurements was performed to the biceps brachii muscle (BB), the forearm flexors (FF), the rectus femoris muscle (RF), the tibialis anterior muscle (TA) according to a standard protocol[;<sup>1</sup> The captured images were analysed offline for muscle thickness and echo intensity(EI) by means of computer-assisted grayscale histogram analysis. Manual muscle testing (MMT) was assessed and serum creatine kinase (CK) levels were measured. Also, Quantitative electromyography (QEMG) assessment was preformed as BB and RF were studied on the most affected side with emphasis on motor unite potential (MUP) duration, area to amplitude ratio (AAR). <h3>Results</h3> In JDM patients, EI of the proximal muscles (BB and RF) at 12 months follow up (75.32±29.84 and 74.73±25.58 respectively) were highly significantly decreased compared to their baseline EI (127.18±50.62 and 100.68±33.65 respectively) (p&lt;0.05). Also, EI of BB and RF at 12 months follow up showed statistically significant correlation with their MMT(r=−0.51, p&lt;0.05), CK levels (r=0.42, p&lt;0.05) and MUP duration (p&lt;0.05). In DMD patients, EI of BB, RF and TA muscles at 12 months follow up (122.3±41.29, 132.55±41.38 and 136.75±38.02 respectively) were significantly increased compared to their baseline EI (116.7±42.65, 124±43.33 and 133.3±39.57 respectively, p&lt;0.05) . Also, EI of BB, RF and TA at 12 months follow up showed statistically significant correlation with their MMT (r=−0.67,–0.68 and −0.68 respectively, p&lt;0.05), CK levels (r=0.77, 0.76 and 0.7 respectively, p&lt;0.05), MUP duration (r=−0.73,–0.58 and −0.53 respectively, p&lt;0.05) and AAR ratio (r=−0.79,–0.81 and −0.62 respectively, p&lt;0.05). Logistic regression analysis showed that baseline EI were predictive of follow up MMT score in both JDM and DMD patients (p=0.03 and 0.01 respectively). <h3>Conclusions</h3> : Quantitative muscle US is a sensitive, objective technique for measuring the presence and severity of muscle pathology in both JDM and DMD patients. EI is remarkably correlated with MMT, muscle enzymes and quantitative EMG suggesting that it could be a useful follow up tool to reflect disease severity and residual muscle damage. <h3>References</h3> [1] Jansen M, van Alfen N, van der Sanden M, van Dijk J, Pillen S, de Groot I. Quantitative muscle ultrasound is a promising longitudinal follow-up tool in Duchenne muscular dystrophy. Neuromuscular disorders2012;22(4):306–17. <h3>Disclosure of Interest</h3> None declared