Diminished muscle integrity in patients with fibrodysplasia ossificans progressiva assessed with at-home electrical impedance myography

Abstract

Fibrodysplasia ossificans progressiva (FOP) is an ultra-rare disorder involving skeletal dysplasia and heterotopic ossification (HO) of muscle and connective tissue. We aimed to define a novel biomarker in FOP that enables reliable assessment of musculoskeletal tissue integrity. Considering logistical difficulties that FOP patients often face, our goal was to identify an at-home biomarker technique. Electrical impedance myography (EIM) is a non-invasive, portable method that can inform on muscle health. 15 FOP patients (age 10–52) and 13 healthy controls were assessed. Using EIM, multiple muscle groups were characterized per participant in a 45-min period. The Cumulative Analogue Joint Involvement Scale (CAJIS) was implemented to determine mobility burden severity. We additionally evaluated physical activity levels via a Patient-Reported Outcomes Measurement Information System (PROMIS)-based questionnaire. Relative to controls, FOP patients demonstrated significantly lower regional and whole-body phase values at 50 kHz and 100 kHz, indicating more diseased muscle tissue. Lower whole-body phase and reactance values, and higher resistance values, were associated with greater FOP burden (CAJIS score range: 4–30) and lower physical activity levels at 50 kHz and 100 kHz. This study points to the potential utility of EIM as a clinical biomarker tool capable of characterizing muscle integrity in FOP.

A pilot investigation of muscle integrity in patients with ADSSL1 myopathy using electrical impedance myography

“…Across clinical EIM studies involving various neuromuscular disorders, a common finding is a reduction in θ and X, with an increase in R, indicating diseased or compromised muscle tissue. [11][12][13][14][15] We observed S1 and S2. ).…”

“…EIM acquisitions were performed virtually in each participant's home at a single timepoint. The methodology of at‐home EIM data collection, including caregiver training, has been recently described 14 . EIM placement over each muscle was guided by using the Myolex App loaded onto an iPad (Myolex, Inc; Brookline, MA), which was controlled by the trained caregiver.…”

“…The methodology of at-home EIM data collection, including caregiver training, has been recently described. 14 EIM placement over each muscle was guided by using the Myolex App loaded onto an iPad (Myolex, Inc; Brookline, MA), which was controlled by the trained caregiver. Positioning of the EIM device was additionally verified by study staff using Zoom video conferencing.…”

“…Two artifact-free EIM scans were collected per muscle group per participant during the virtual EIM study session. 14 Upper extremity muscle groups were the bilateral lateral deltoids, biceps brachii, wrist extensors, forearm flexors. Lower extremity muscle groups were the bilateral quadriceps, tibialis anterior, and medial gastrocnemius.…”

“…Herein, three ADSSL1 myopathy patients are presented. The objective of the current study was to also perform a preliminary evaluation of a virtual EIM procedure involving patients with ASDDL1 myopathy and age‐gender matched healthy controls (HCs) to further define the pathophysiology of this condition 13,14 …”