LIMB GIRDLE MUSCULAR DYSTROPHIES: P.148 Semiquantitative CT assessment of muscle involvement in limb girdle muscular dystrophy 2A and 2B with the wide range of duration

Abstract

Limb girdle muscular dystrophy (LGMD) 2A and 2B represent the most frequent forms of LGMDs in the Japanese population. We investigated muscle CT images of both LGMDs with the wide range of disease duration to characterize muscle involvement of this disease and to determine the rate of progression. We applied the Mercuri grading system to CT scans cross-sectional images of six cross section (shoulder, upper and lower trunk, pelvis, thigh and calf). This study included 15 patients with LGMD2A (8 male, 7 female, 41.2±21.6) and 27 patients with LGMD2B (13 male, 14 female, 50.5±17.4 years) registered in IBIC (Integrative Brain Imaging Center:the database of skeletal muscle images in Japan). The patients were classified into 3 groups according to disease duration: stage1 (<10years), stage 2 (11∼30years) and stage 3 (31<years). In stage1, both types showed early predominant degeneration of subscapularis, paraspinal, gluteus minimus and the medial head of the gastrocnemius. There was mild muscle involvement in 2A, but moderate involvement in 2B at shoulder level. The involvement of the pelvic muscles in 2A was equal to, or slightly more than those of 2B. The degeneration of the posterior segment of the thigh with sparing of the gracilis muscle was observed in both. In stage2, biceps brachii muscle was much more severely involved than triceps brachii muscle in 2A, but this finding was not true for 2B. Patchy involvement of the quadriceps was observed in 2B. In stage3, almost all muscles were replaced by fat in 2B whereas there were some residual muscles in 2A at the thigh and calf level. The rate of disease progression was much slower in LGMD2A than LGMD2B. This finding is concordant with our previous study using %MVI.