Electrical Impedance Myography for Evaluating Paretic Muscle Changes After Stroke

Abstract

Electrical impedance myography (EIM) was used to assess the paretic muscle intrinsic electrical properties post stroke. Twenty-seven subjects with chronic hemiparesis participated in this study. Muscle impedance was measured by applying high-frequency, low-intensity alternating current to biceps brachii muscles. Major EIM parameters, resistance ( ), reactance ( ), phase angle ( ), and electrical anisotropy ratios (AR) of the three parameters, were examined at 50 kHz. Statistical analysis demonstrated significant reduction of reactance, phase angle, AR of resistance, and AR of reactance in the paretic muscle compared with the contralateral side (Paretic X: , contralateral X: , and p < 0.001; Paretic : , contralateral : 14.5 ± 0.82°, and p < 0.001; Paretic AR of R: 0.969 ± 0.013, contralateral AR of R: 1.008 ± 0.011, and p < 0.02; and Paretic AR of X: 0.981 ± 0.066, contralateral AR of X: 1.114 ± 0.041, and p < 0.02). Correlation analysis, however, did not show any significant relationship between EIM parameters and clinical assessments. Findings of this paper indicated significant changes in the muscular intrinsic electrical properties after stroke, possibly related to structural modifications induced by loss of muscle fibers or fat infiltration as well as changes in the quality of cell membranes post stroke.

Design and Evaluation of an Electrical Bioimpedance Device Based on DIBS for Myography during Isotonic Exercises

“…Our measurements of |Z rest | ( Figure 14) converges with the ones from [25], where, after a set of exercises, the bioimpedance magnitude spectrum decreases for all frequencies. A drop in the bioimpedance real part when reaching fatigue was also reported in [22,24]. Albeit our project evaluated only one volunteer, the protocol ( Figure 2) was repeated 16 times, and the outcomes for all days were consistent.…”

“…Rutkove in 2002 made measurements to understand the mechanisms of impedance changes in neuromuscular diseases [21]. The resistance and reactance depend on the muscle length and cross-sectional area, so one can assume parameters such as muscle mass, shape and tissue quality defines the muscle impedance [22]. One of the major challenges of EBIM is to identify the contributions of each tissue (cutaneous, fat, muscle and bone) in the measurement [23].…”

“…There are diverse applications of EBIM in literature, some are: evaluation of paretic muscle changes after stroke [22], fatigue [24][25][26][27], equine muscle diseases [28], detection of muscle activation [29], skeletal muscle injuries [30,31] and identification of many neuromuscular diseases [32].…”

“…EBIM researchers generally use manufactured devices [22,26] or build a prototype based on data acquisition cards and other devices [24,29,33]. The works that have characterized the device showed relatively smaller errors, but none of them used broadband excitation, and two could measure in real time [29,33].…”

Assessing Hand Muscle Structural Modifications in Chronic Stroke

“…Applications of EIM to assess poststroke muscle conditions are relatively limited in the literature. In a previous study, we examined muscle impedance properties in the biceps brachii and found significant changes of muscle structural properties in the paretic side ( 24 ). Since proximal muscles demonstrate different extents of impairment from distal muscles ( 25 ), it remains unknown whether findings from biceps brachii are applicable to hand muscles.…”