Electrical impedance myography captures features of macroscopic and microscopic muscle structure in facioscapulohumeral muscular dystrophy

Topic:

Clinical Trials

Poster Number: P195

Author(s):

Danielle Dixon, University of Washington MDA Clinic, Dennis Shaw, MD, University of Washington, Lara Riem, PhD, Springbok Analytics, Leann Lewis, MSc, CCRP, University of Rochester, Jeffrey Statland, MD, University of Kansas Medical Center, Katy Eichinger, PT, PhD, University of Rochester, Stephen Tapscott, MD, PhD, Fred Hutchinson Research Center, Karlien Mul, MD, PhD, Radboud university medical center, Johanna Hamel, MD, The university of Rochester, Rabi Tawil, MD, University of Rochester, Seward Rutkove, MD, Beth Israel Deaconess Medical Center, Buket Sonbas Cobb, Beth Israel Deaconess Medical Center, Seth Friedman, PhD, Seattle Children's Hospital, Leo Wang, MD, PhD, University of Washington

BACKGROUND:
Electrical impedance myography (EIM) has been proposed as an efficient, non-invasive biomarker of muscle composition in facioscapulohumeral muscular dystrophy (FSHD).
OBJECTIVE:
We investigate whether EIM parameters are associated with muscle structure measured by magnetic resonance imaging (MRI), muscle histology, and transcriptomic analysis as well as strength at the individual leg muscle level.
METHODS:
We performed a multi-center cross-sectional study enrolling 33 patients with FSHD. EIM measurements were recorded from bilateral vastus lateralis, tibialis anterior (TA), and medial gastrocnemius muscles and compared to quantitative muscle volume measures by MRI as well as knee extension and ankle dorsiflexion strength by quantitative muscle testing. EIM measurements of the TA were further compared to muscle histology and transcriptomic analysis (RNAseq) of muscle and fat content.
RESULTS:
EIM phase at multiple frequencies was positively associated to the amount of muscle measured by MRI (ρ = 0.48 to 0.70, p ≤ 0.001) and negatively associated to the amount of fat replacement of muscle (ρ = -0.53 to -0.73, p ≤ 0.001). EIM phase of the vastus lateralis and TA was positively associated with knee extension and ankle dorsiflexion strength normalized to age and sex (ρ = 0.45 to 0.60, p <0.0001). The bilateral TA muscles were biopsied and transcriptomic analysis also showed that EIM phase was positively associated with amount of muscle (ρ = 0.33 to 0.35, p < .01) and negatively associated with amount of fat (ρ = -0.36 to -0.56, p < .001). CONCLUSIONS: This study supports the hypothesis that EIM is associated with the amount of muscle in patients with FSHD that can be measured by MRI, strength, and amount of muscle RNA measured in biopsy samples. These data provide further convergent validity for the use of EIM as a potential non-invasive biomarker to assess muscle health in FSHD.