FIGURE 3.

Pattern of muscle involvement in the lower limbs. Magnetic resonance imaging scans from four patients, from milder (left) to severer affected (right), showing the most frequent pattern of muscle involvement in the lower limbs (arrows): gastrocnemius and distal quadriceps (vasti) followed by glueteus minimus and soleus. Rectus abdominis, flexor hallucis longus, tibialis anterior and gastrocnemius lateralis are mildly affected. Psoas, proximal quadriceps (vasti) and tibialis posterior are spared until the late‐end stage of disease (arrowheads). Note the atrophy of quadriceps regardless of overall severity (milder patient, outlined arrow). Note the distal‐proximal gradient of fibro‐fatty replacement of sartorius (asterisk)