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SHEAR WAVE ELASTOGRAPHY IN PATIENTS WITH SPINAL MUSCULAR ATROPHY TYPE 2-3

Objectives This study aimed to investigate selective muscle involvement by shear wave elastography (SWE) in patients with spinal muscular atrophy (SMA) types 2 and 3 and determine the diagnostic contributions of SWE and magnetic resonance imaging (MRI).

Methods Seventeen patients with SMA types 2 and 3 were included in the study. SWE was used to evaluate tissue elasticity of the upper and lower extremity muscles. Fatty degeneration and atrophy of the paraspinal muscles was evaluated using 1.5-Tesla MRI. SWE values and MRI scores of the paraspinal muscles were compared.

Results Among the upper extremity muscles, SWE values were the highest for the triceps brachii; however, no significant difference was noted (p=0.23). Patients with a longer disease duration were considerably more likely to have worse SWE values for the triceps brachii (r=0.636,p=0.006). Among the lower extremity muscles, SWE values for the iliopsoas were significantly higher than those for the gluteus maximus (p<0.001). A positive correlation was found between SWE values and MRI scores of the left and right paraspinal muscles (r=0.49,p=0.045;r=0.67,p=0.003).

Conclusion This is the first study to report the assessment of muscle involvement using SWE in patients with SMA. Our findings confirm the presence of SMA-specific selective muscle involvement. Additionally, SWE and MRI findings were similar in showing muscle involvement. SWE is a noninvasive practical method that can be used to show muscle involvement in patients with SMA, understand the pathogenesis of segmental involvement, and guide future treatments or monitor the effectiveness of existing new treatment alternatives.
Keywords: spinal muscular atrophy, shear wave elastography, magnetic resonance imaging