source: American Academy of Neurology
Craig Zaidman, Seward Rutkove, Julaine Florence, Anne Connolly, Brenda Wong, Michele Yang, Basil Darras, Kush Kapur, Jose Bohorquez
To evaluate the sensitivity to disease progression of Duchenne muscular dystrophy (DMD) of a dedicated electrical impedance myography (EIM) device.
Recent work in DMD has shown that EIM is sensitive to disease progression and the therapeutic benefit of corticosteroids. Most work to date has used custom-designed, off-the-shelf impedance devices and has been performed at a single center. Here we evaluate a dedicated EIM system that allows for rapid and improved data acquisition.
In this 4-center study, healthy boys and those with DMD were assessed at 0, 3, 6 and 12 months after enrollment. The EIM 1103 System (Skulpt, Inc) was utilized with measurements performed on the dominant side on the deltoid, biceps brachii, wrist extensors, wrist flexors, vastus lateralis, tibialis anterior, and medial gastrocnemius. Multifrequency impedance data from 1kHz to 1MHz were collected on each muscle. Subjects in the 3–12-year-old group also underwent functional testing. A linear mixed effect model was applied, with random intercepts and slopes, alpha=0.05, 2-tailed for all analyses.
Seventy-one boys with DMD and 72 healthy controls, mean age 8.2 years (range 0.6–17.4 years) and 8.3 years (range 0.3–17.9 years), respectively, were enrolled. A variety of multifrequency EIM measures demonstrated differences in the longitudinal EIM parameters over time in both younger and older boys. For example, the previously reported 100–500 kHz phase slope parameter averaged across all 7 muscles was reduced (−0.0563 (standard error 0.0164)) in boys with DMD compared to controls (p=0.0009) at 12 months. Utilizing this measure as an outcome in a 12-month clinical trial would require a sample size of just 19 subjects/arm assuming an effect size of 1.0.
EIM multifrequency parameters obtained with this dedicated system are sensitive to disease progression in DMD. Further analysis of the EIM data and its relationship to the simultaneously obtained functional measures is underway.
Washington University, USA; Beth Israel Deaconess Medical Center/Harvard Medical School Boston, USA; Cincinnati Children’S Hospital Medical Center, USA; Children’S Hospital Colorado, USA; Boston Children’s Hospital/Harvard Medical School, USA; Skulpt Inc, USA