Noninvasive assessment of neuromuscular diseases using electrical impedance

DESCRIPTION (provided by applicant): Neuromuscular disorders, ranging from severe generalized diseases such as muscular dystrophy and amyotrophic lateral sclerosis (ALS) to localized conditions, including nerve injuries and radiculopathy, impact the lives of millions of people in the US and around the world. Today, diagnostic tools and general outcome measures remain largely qualitative and imprecise. Moreover, the frequently used invasive technique of needle electromyography is not only subjective, but is also painful and generally poorly tolerated. Furthermore, these diagnostic tools often require considerable patient cooperation, which can also lead to variability in data quality, especially when children are being tested. The lack of an accurate, noninvasive technology not only affects the diagnosis and treatment of patients, it also limits the ability to gauge the efficacy of new treatments during clinical trials. Thus, a technology that can rapidly, quantitatively, reliably, and noninvasively evaluate neuromuscular disease status with minimal patient cooperation, would find wide application not only as a diagnostic tool, but also as a means of tailoring patient care after diagnosis and for streamlining clinical drug trials. One technology that has shown great promise in this regard is electrical impedance myography (EIM). Over the past decade, EIM techniques have been studied extensively in human subjects in a variety of neuro- muscular disorders, and these studies have provided very promising results, including demonstrating that these techniques cannot only differentiate diseases from one another but also can assist in accurately assessing disease progression or remission over time. Almost all of these studies, however, have been made with commercially available impedance devices that are not optimized specifically for muscle health assessment. Thus, the goal of this Phase I SBIR application is to fund the initial development and testing of such a device, including the employment of novel mechanical sensor techniques and electronics to achieve better accuracy over a wider frequency range than possible with off-the-shelf systems. The specific aims of this project thus are: 1) to develop a set of robust, reconfigurable mechanical sensors that can interface with a variety of commercial impedance measurement devices; 2) to develop an electronic impedance-measuring system with novel circuit topology, specifically optimized for fast, accurate, and wide-bandwidth EIM measurements; and 3) to evaluate the developed system in a variety of test media. With the successful completion of these three aims, we will be well-positioned to test this device in clinical trials as part of a planned Phase II SBIR grant. PUBLIC HEALTH RELEVANCE: Neuromuscular disorders impact the lives of millions of people in the US and abroad. Diagnostic tools used for assessing muscle and nerve dysfunction remain largely qualitative, inaccurate, and painful, and are particularly difficult to use with children. The technique of electrical impedance myography (EIM) has shown great promise in overcoming these limitations. Thus, the overall goal of this project is to develop a handheld, noninvasive electrical impedance device that can perform accurate, rapid assessments of muscle health.