Electrical Impedance Methods in Neuromuscular Assessment: An Overview

Abstract

Electrical impedance methods have been used as evaluation tools in biological and medical science for well over 100 years. However, only recently have these techniques been applied specifically to the evaluation of conditions affecting nerve and muscle. This specific application, termed electrical impedance myography (EIM), is finding wide application as it can provide a quantitative index of muscle condition that can assist with diagnosis, track disease progression, and assess the beneficial impact of therapy. Using noninvasive surface methods, EIM has been studied in a number of conditions ranging from amyotrophic lateral sclerosis to muscular dystrophy to disuse atrophy. Data support that the technique is sensitive to disease status and can offer the possibility of performing clinical trials with fewer subjects than would otherwise be possible. Recent advances in the field include improved approaches for using EIM as a "virtual biopsy" and the development of combined needle impedance-electromyography technology.

Biomarkers and the Development of a Personalized Medicine Approach in Spinal Muscular Atrophy

“…The method involves quantitative measurement of changing parameters in the muscle's extra and intracellular fluid resistance, and cell membrane reactance (as a measure of its capacitance), to a sinusoidal current, applied at varying frequencies (96). This measure reflects the changing intrinsic properties of the muscle (97), denoting tissue quality, including changes secondary to fibrosis, denervation, and edema (98). The adult onset disease amyotrophic lateral sclerosis (ALS) has acted as a model for biomarker exploration in disease of upper and lower motor neurons.…”

Correlation Between Muscle Structures and Electrical Properties of the Tibialis Anterior in Subacute Stroke Survivors: A Pilot Study

“…They are considered as biomarkers that can be used to assess neuromuscular disease progression and response to therapy (Rutkove et al, 2002). In comparison with other muscle property assessment techniques such as magnetic resonance imaging and electromyography, EIM has less requirement on patients’ cooperation or subjective judgments, and has shorter time on performing the measurement and data analysis (Rutkove and Sanchez, 2019). However, as an indirect measurement method, EIM itself could not record other architecture information such as the muscle fiber arrangement.…”

Altered muscle electrical tissue properties in a mouse model of premature aging

“…One approach that has offered potential benefit for this purpose is electrical impedance myography (EIM). In EIM, a low‐amplitude, high‐frequency electrical current is passed through a muscle of interest and the consequent voltage is measured . Alterations in muscle condition, including myofiber atrophy, and the deposition of fat and connective tissue, impact the resulting voltages.…”

“…In EIM, a low-amplitude, high-frequency electrical current is passed through a muscle of interest and the consequent voltage is measured. 5 Alterations in muscle condition, including myofiber atrophy, and the deposition of fat and connective tissue, impact the resulting voltages. Thus, EIM is potentially sensitive to histological changes in muscle that are thought to be closely related to the development of sarcopenia.…”