Fig. 1

Physical examination findings and lower body MRI of patient. Differential asymmetric distal upper limb weakness of finger extensors and finger abductors (A). No significant atrophy is observed (B-D). Muscle MRI T1 sequence findings of patient at the level of the pelvic girdle (E), thighs (F) and calves (G). There is no significant loss of muscle volume or presence of muscle edema. E Mild symmetric fatty infiltration noted of the bilateral gluteus maximus (arrowhead) and gluteus medius (arrow). F Moderate fatty infiltration of the bilateral sartorius (solid arrowhead), mild infiltration of the adductor magnus (hollow arrowhead), posterior compartment of the thigh, particularly the bilateral semimembranosus (arrow) and biceps femoris (*). G Moderate fatty infiltration of the bilateral extensor digitorum longus muscles (solid arrowhead), mild fatty infiltration of bilateral tibialis anterior (hollow arrowhead), as well as mild fatty infiltration of the bilateral soleus muscles (arrow)