This document discusses the role of neuroimaging in muscle and peripheral nerve diseases. It begins by explaining how MRI is commonly used to evaluate neuromuscular disorders by detecting signal changes in muscles or nerves. It then classifies peripheral neuropathies and myopathies. The document discusses the pathology and pathogenesis of several muscle and nerve diseases like GBS, CMT, muscular dystrophies and inflammatory myopathies. It provides examples of characteristic patterns of muscle involvement seen on MRI for different conditions.

1. بسم الله الرحمن الرحيم

2. بسم الله الرحمن الرحيم ﴿ واتقوا الله ويعلمكم الله والله بكل شئ ﹴ عليم ( سورة البقرةالآية (282)

26. Fig. (1): Duchenne's muscular dystrophy in a 7-year-old boy, brother of patient in Figure 28. Axial T1-weighted spin-echo MR image (TR/TE, 500/20) shows moderate fatty infiltration with patchy pattern involving bilateral thigh muscles. Bilateral semimembranosus (Sm), vastus intermedius (Vi), and vastus medialis (Vm) muscles are less involved. Note sparing of bilateral gracilis (G), sartorius (s), and semitendinosus (St) muscles (Wing et al., 2002).

34. Fig. (2): 64-year-old man with polymyositis. Note diffuse edema and inflammation of obturator externus ( arrowhead ) and pectineus ( arrow ) muscles on axial STIR image (Maximilian et al., 2009).

36. Fig. (3): 42-year-old man with known dermatomyositis. Axial STIR image shows diffuse hyperintensity in some thigh muscles (arrowhead, vastus lateralis muscle). Note also increased signal in subcutaneous tissue septa (arrow) and skin thickening (Maximilian et al. 2009).

41. Fig. (4): T1W MRI, transverse sections of the proximal thigh in three patients with congenital myopathies secondary to mutations in the RYR1 gene. Note the marked increase in abnormal signal within the vasti, sartorius, and adductor magnus, and relative sparing of the rectus femoris, adductor longus, gracilis, and semitendinosus ( a and b ), which is more obvious in the patient with more severe weakness ( c ) (Eugenio et al., 2007).

43. Fig. (5): Selective muscle involvement in a 59-year-old man (Carsten and Joachim, 2007).

46. Fig. (6): Normal brachial plexus. (A) Oblique coronal T1-weighted image (to maximize long axis of brachial plexus) of the lower brachial plexus shows the brachial plexus isointense to muscle extending from the trunks to cords (white arrows) as well as the proximal roots of C8 and T1. (B) Oblique coronal STIR images (same plane as A) show the normal brachial plexus (white arrows) with signal higher than muscle but less than vascular structures in the neck (Maravilla et al., 1998).

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