Purpose of review: In this article, we provide an overview of electrical impedance myography (EIM), including its technical and theoretical basis, a summary of its varied applications, and ongoing developments.
Recent findings: EIM has been used as a disease severity biomarker in a variety of disorders affecting the muscle, ranging from amyotrophic lateral sclerosis (ALS) to muscular dystrophies to disuse atrophy due to the weightlessness of space. In ALS, studies have demonstrated that major reductions in sample size in clinical trials can be achieved. Similarly, in the Duchenne muscular dystrophy, the technique tracks disease progression and is sensitive to the beneficial effect of steroids. More basic work has demonstrated that EIM can provide a non-invasive means of tracking muscle fiber size. Ongoing innovations include the development of techniques for assessing muscle contraction. EIM is gradually being adopted as a useful, practical, and convenient tool for the assessment of neuromuscular conditions.
Keywords: Disuse; Electrical impedance; Injury; Muscle; Myopathy; Neurogenic disease.