Evaluation of Muscle Atrophy: Comparison between Limb-Girdle Muscular Dystrophies, ALS and Metabolic Myopathies (P07.197)

Abstract

Objective: To study neuromuscular disorders by a quantitative measurement to evaluate muscle atrophy by MRI. Background The fibro-fatty replacement and myoedema are the most common indexes used to evaluate the muscle involvement in LGMD on MRI. However, many published scores are not quantitative and do not assess the extent of muscle atrophy in neuromuscular disorders. Design/Methods: We selected images obtained from T1 MRI sequences of the thigh muscles, at a distance of about 15 cm from the head of the femur. We measured the muscle area of the left quadriceps femoris and of the left vastus lateralis in 11 patients matched by sex and age, affected with 2 lipid myopathies, amyotrophic lateral sclerosis, FSHD, myofibrillar myopathy, metabolic myopathy, 2 LGMD2A, LGMD1F, localized myositis ossificans, aspecific myopathy. Results: Vastus lateralis muscle. The area was in average 963 ± 303 mm 2 . In this group of patients we have identified two subgroups, one including 5 patients with a high degree of atrophy ( high atrophic group ), whose values ranged from 400 to 900 mm 2 (mean 658.7), and one including 6 patients with a low degree of atrophy ( low atrophic group ), whose values ranged from 900 to 1400 mm 2 (mean 1217.8). Quadriceps femoris muscle in-toto. The measure of muscle area was in average 3711 ± 792 mm 2 . In the high atrophic group the values ranged from 2400 to 3400 mm 2 (mean 2966), while in the low atrophic group the values ranged from 3700 to 5000 mm 2 (mean 4332). Conclusions: Imaging examination may suggest a characteristic pattern of muscle involvement: i.e. in LGMD2A the posterior compartment is often involved. The values of cross sectional muscle area appeared to be useful indexes to evaluate muscle atrophy in LGMD, ALS and metabolic myopathies. The effect of drug treatment or of exercise or rehabilitation can be evaluated by quantitative muscle MRI. Disclosure: Dr. Angelini has received personal compensation for activities with Genzyme Corporation. Dr. Fanin has nothing to disclose. Dr. Peterle has nothing to disclose.