The aim of our study is to Assess skeletal muscle structural status in children with inflammatory myositis and Duchenne muscular dystrophy using musculoskeletal ultrasound and to perform a longitudinal follow up of these changes over 2 years and to assess the relation between these findings with clinical parameters, functional scales, biochemical and electromyographic tests.

This study will be carried out on two groups:

• Group (I): fifty children diagnosed to have duchenne muscular dystrophy and inflammatory myositis.

Group (II): including 20 healthy children matching age and sex as control group.

patients will be subjected to

(A) Clinical evaluation

1. Complete history taking.
2. Thorough clinical examination.
3. Body mass index (BMI) assessment.
4. Quantitative muscle strength tests
5. Functional grading
6. Childhood Myositis Assessment Scale. 7 (B) Laboratory assessment:

All patients will be subjected to the following measurements:

1. Serum creatine kinase levels (CK).
2. Serum Lactate dehydrogenase levels
3. Serum of Liver enzymes (SGOT& SGPT) levels.

(C) Electromyographic (EMG) assessment:

(D) Musculoskeletal ultrasound assessment (E) Statistical analysis

Inclusion Criteria:

• children with Duchenne muscular dystrophy (DMD). Diagnosis with DMD was established according to DMD diagnostic criteria (Jennekens et al., 1991).
• children with juvenile dermatomyositis (JDM) according to Bohan and Peter diagnostic criteria ( (Bohan and Peter, 1975).

Exclusion Criteria:

• Patients with age less than 2 years were excluded from the study due to inability to perform manual muscle testing and functional scales.
• If no final diagnosis could be established.
• The presence of a concomitant illness that may result in peripheral neuropathy or myopathy.

the study will be performed on 2 groups Group (I): fifty children diagnosed to have inflammatory myositis and Duchenne muscular dystrophy Group (II): including 20 healthy children matching age and sex as control group.