The Promise of EIM
Electrical impedance myography (EIM) is a non-invasive, painless assessment method that quantifies the passive electrical behavior of muscles. It is based on the idea that conductivity and permittivity in a diseased muscle are altered, and these alterations in the muscle can cause changes in the voltage generated.
EIM is an impedance-based technology in which an imperceptible, high-, multi-frequency (e.g., 1 kHz to 10 MHz) electrical current is applied to an area of tissue across two electrodes and the resulting voltage signals measured across two sense electrodes.
EIM evaluates specific regions of muscle by specifically forcing the current along or across myofibers. It is sensitive to microscopic tissue morphology and composition, including cell atrophy, density, membrane integrity, subcellular structures, and interstitial changes, such as fibrosis, edema, inflammation, and fat deposition.
Importantly, EIM does not require the active participation of the patient, providing quantitative data on functional capability while the muscle and patient remain entirely at rest.