Electrical impedance myography in individuals with collagen 6 and laminin α-2 congenital muscular dystrophy: a cross-sectional and 2-year analysis

Abstract

Introduction: Electrical impedance myography (EIM) is a noninvasive electrophysiological technique that characterizes muscle properties through bioimpedance. We compared EIM measurements to function, strength, and disease severity in a population with congenital muscular dystrophy (CMD).

Methods: Forty-one patients with CMD, either collagen 6 related disorders (COL6-RD; n = 21) or laminin α-2-related disorders (LAMA2-RD; n = 20), and 21 healthy pediatric controls underwent 2 yearly EIM exams. In the CMD cohorts, EIM was compared with functional and strength measurements.

Results: Both CMD cohorts exhibited change over time and had correlation with disease severity. The 50-kHZ phase correlated well with function and strength in the COL6-RD cohort but not in the LAMA2-RD cohort.

Discussion: EIM is a potentially useful measure in clinical studies with CMD because of its sensitivity to change over a 1-year period and correlation with disease severity. For COL6-RD, there were also functional and strength correlations. Muscle Nerve 57: 54-60, 2018.

Keywords: COL6 related dystrophies; LAMA2 related dystrophies; congenital muscular dystrophy; electrical impedance myography; neuromuscular disorders.

Conflict of interest statement

Conflicts of Interest: None of the authors have any financial relationship with the company that manufactures the product used in this study or any other conflict of interest.

© 2017 Wiley Periodicals, Inc.

Figures

FIGURE 1.

EIM electrode arrays. P/N 20–00036 infant sensor (A), P/N EIM 007–002 pediatric sensor (B), and P/N EIM-014–009 adult sensor (C). The electrode arrays are adjacent to the sensor holder. EIM, electrical impedance myography.

FIGURE 2.

Change in EIM at 50 kHZ in 1-year interval. Comparison of 8-muscle EIM average for COL6-RD, LAMA2 -RD. and HV for phase (A), reactance (B), and resistance (C). Data are mean ± SE. COL6-RD, collagen 6 related disorder; EIM, electrical impedance myography; HV, healthy volunteers; LAMA2-RD, laminin α−2 related disorder.

FIGURE 3.

PGCIS vs. 8-muscle EIM phase average. Dotplot representation with best fitted linear line of COL6-RD cohort (n= 19; A) and LAMA2-RD cohort (n= 20; B). The PGCIS is rated on a 5-point scale as 1, mild; 2, mild-moderate; 3, moderate; 4, moderate-severe; and 5, severe. COL6-RD, collagen 6 related disorder; EIM, electrical impedance myography; LAMA2- RD, laminin α−2 related disorder; PGCIS, Physician Global Clinical Impression of Severity.

FIGURE 4.

Ability to perform 10-meter run vs. 8-muscle EIM phase average (MFM item 30). Dotplot representation with best fitted linear line of COL6-RD cohort (n = 20; A) and LAMA2-RD cohort (n = 20; B). COL6-RD, collagen 6 related disorder; EIM, electrical impedance myography; LAMA2-RD, laminin α−2 related disorder; MFM, Motor Function Measure.