Neuromuscular diseases (NMDs) are a group of disorders caused by an abnormality of any component of the motor unit (anterior horn cell, peripheral nerve, neuromuscular junction and muscle). Responsive outcome measures are needed to quantify the disease status in patients with NMDs. Muscle ultrasound (US) provides a promising fast, painless noninvasive tool for quantitative assessment and follow up of NMDs progression and response to therapeutic approaches especially in young children who may have limitations in performance of quantitative muscle strength tests, functional scales. Neuromuscular diseases cause structural muscle changes that can be detected by US. Increased muscle echo intensity (EI) on US is indicative of a neuromuscular disorder.
The aim of our study was to assess skeletal muscle structural status in children with myositis and neuromuscular diseases using muscle US, perform a longitudinal follow up of these changes over time and correlate these findings with clinical parameters, functional scales, biochemical and electromyographic tests.
Twenty-nine children diagnosed to have neuromuscular disorders were included into this study. They were divided into three groups: Group (I), ten children diagnosed with Duchenne muscular dystrophy (DMD) by pediatric neurologist according to DMD diagnostic criteria. Group (II), eleven children diagnosed with juvenile dermatomyositis (JDM) by pediatric rheumatologist according to Bohan and Peter diagnostic criteria. Group (III), eight children diagnosed with neuropathic disorders by pediatric neurologist. All groups were recruited from the inpatients and outpatients' clinic of the Rheumatology, Rehabilitation and Physical Medicine department & Pediatric Department at Benha University Hospital and Benha Children Hospital.
All patients were evaluated at baseline, at 4-months & at 8-months follow up using:
(A) Clinical evaluation
1. Complete history taking.
2. Thorough clinical examination.
3. Body mass index (BMI) assessment.
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4. Manual muscle testing (MMT): The following muscles were tested bilaterally: the biceps brachii muscle (BB), the forearm flexors (FF), the rectus femoris muscle (RF), the tibialis anterior muscle (TA). The strength of each muscle group was given a score using Kendall’s 0 –10 point scale.
5. Functional grading (Vignos and Brooke scales).
6. Childhood Myositis Assessment Scale (CMAS).
7. Childhood Health assessment questionnaire (CHAQ).
(B) Laboratory assessment:
1. Serum creatine kinase (CK) levels.
2. Serum Lactate dehydrogenase (LDH) levels.
3. Serum of Liver enzymes (AST & ALT) levels.
(C) Quantitative Electromyography (QEMG) assessment:
The following muscle: biceps brachii (BB) and rectus femoris (RF) were studied on the most affected side. The following motor unit point (MUP) parameters were automatically determined: duration (ms), peak-to-peak amplitude (V), area (V*ms) and area to amplitude ratio (AAR). The EMG interference pattern analysis provided the number of turns per second (NT), the mean amplitude change between successive turns (MA) and NT: MA ratio.
(D) Quantitative muscle ultrasound assessment:
Quantitative US measurements were performed to biceps brachii, forearm flexors, rectus femoris and tibialis anterior muscles. A standard protocol for quantitative US measurements was performed. US machine settings were kept constant throughout the study. The mean muscle echo intensity (EI) were determined using a computer-assisted grey-scale analysis. Muscle thickness (MT) was measured during examination with electronic calipers at standardized positions.
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The results of this study were as follows:
Comparison between demographic characteristics, Clinical, electromyography and ultrasonography results of all groups at baseline evaluation:
At baseline evaluation, disease duration was statistically significant different (p |
