Individual details of imaging and PUL findings at shoulder, arm and forearm level.

<p>The shading reflects the severity of involvement with the score of 0 shown as a white cell, score of 1 as pale green, score of 2 as yellow, score of 3 as orange and score of 4 as red. The grade 2.5 was used to identify patients with 2b involvement. Del = deltoid; suprasp = supraspinatus; infrasp = infraspinatus; subscap = subscapularis; pec = pectoralis; corac = coraco-brachialis; serr = serratus anterior; lat = latissimus dorsi; bic = biceps brachii; brac = brachialis;tri = triceps brachii; sup = supinator;pron = pronator teres;F cp = flexor carpi radialis; palm = palmar; F ds = flexor digitorum superficialis; F cu = flexor carpi ulnaris; Fdp = flexor digitorum profundus; Anc = anconeus; E cu = extensor carpi ulnaris; Edm = extensor digiti minimi; E d = extensor digitorum; E cr = extensor carpi radialis; Br R = brachioradialis; F pl = flexor pollicis longus; E pl = extensor pollicis longus. Ambulant (E) = ambulant early; Ambulant (L): ambulant late; Non ambulant (E) = non ambulant early; Non ambulant (L): non ambulant late.</p

T1-weighted axial MRI of the shoulder.

<p>T1-weighted axial MRI of the shoulder at the level of the humeral head (H) showing increased signal suggestive of fatty replacement in the muscles at this level. The involvement is milder in the youngest ambulant patients aged 10 and 11 (a and b respectively) with more evident fatty replacement in the subscapularis (arrowhead) and infraspinatus (arrow) and more marked in the older non-ambulant ones, both 17 years old (c and d), with severe involvement of all the muscles shown in image d.</p

T1-weighted axial MRI of the forearm.

<p>T1-weighted axial MRI of the forearm at the level of the radial tuberosity showing increased signal suggestive of fatty replacement in the forearm muscles, especially in the supinator (arrow) and pronator teres (arrowhead). The involvement is milder in the youngest ambulant patients aged 8 and 14 (a and b respectively) and more marked in the older non-ambulant ones, both aged 17 (c and d), with severe involvement shown in image d. R (radius); U (ulna).</p

PUL and patients age.

<p>Details of the PUL scores according to age.</p

Pul and MRI total scores.

<p>Details of the PUL and MRI total scores.</p

T1-weighted axial MRI of the arm.

<p>T1-weighted axial MRI of the arm at the mid-level of the humeral shaft (h) showing progressive increased signal suggestive of fatty replacement in the arm muscles. The involvement is milder in the youngest ambulant patients aged 5 and 11 (a and b respectively) and more marked in the older non-ambulant ones, both 17 years old (c and d) with severe involvement of all the muscles shown in image d.</p

Pul entry items and MRI total scores.

<p>Details of the PUL entry items and MRI total scores. The entry items range from score 0 –no useful hand function—to score 6 full shoulder abduction–no weakness.</p