Electrical Impedance Myography Discriminates Congenital Muscular Dystrophy from Controls (P5.087)

OBJECTIVE: To evaluate the discriminative value of electrical impedance myography (EIM) in distinguishing congenital muscular dystrophy (CMD) from controls. BACKGROUND: EIM is an emerging non-invasive, highly reproducible electrophysiological technique that objectively characterizes muscle structure and composition by measuring bioimpedance. In EIM, a high frequency, low intensity electrical current is applied to a limb, and the resulting voltages are measured over a discrete region of muscle. In degenerative neuromuscular disorders, muscle fibers are lost and are replaced by fibrous and fatty tissue, altering the bioimpedance of muscle tissue. Here we evaluate the ability of EIM to discriminate CMD from controls. DESIGN/METHODS: A total of 37 children, aged 4 to 19 years, mean age 10.8 years with genetically or biopsy confirmed CMD and a total of 9 healthy children, aged 7 to 16 years, mean age 11.6 years, were evaluated with 50-kHz EIM. The CMD group consisted of 19 children with collagen 6 related dystrophy, aged 7 to 19 years, mean age 11.6 years, and 18 children with LAMA2 related dystrophy, aged 4 to 18 years, mean age 9.9 years. EIM derived measures included: (1) reactance, a measure of muscle cell membrane integrity, (2) resistance, a measure of extra and intracellular fluid content, and (3) phase angle, which is derived from both reactance and resistance. RESULTS: Mean 8-muscle EIM phase was significantly decreased (p<0.001) and resistance was significantly increased (p<0.001) in the CMD subjects versus healthy volunteers, but there was no significant difference in reactance between these two populations. Of note, mean 8-muscle EIM resistance was significantly increased (p=0.016) in LAMA2 related muscular dystrophy compared to collagen 6 related dystrophy, but there was no significant difference in phase or reactance between these two groups. CONCLUSIONS: Our preliminary findings suggest that EIM may be useful in discriminating CMD from controls and may serve as a useful biomarker to follow disease progression in clinical trials. Study Supported by: National Institutes of Health/NINDS-13-N-0165 and NINDS-12-N-0095 Disclosure: Dr. Schwartz has nothing to disclose. Dr. Salman has nothing to disclose. Dr. Dastgir has nothing to disclose. Dr. Lear has nothing to disclose. Dr. Bonnemann has nothing to disclose. Dr. Lehky has nothing to disclose.