Innovative Electrode Designs for Next Generation Electrical Impedance Myography

Myolex, Inc., Brookline MA

Investigators

Abstract

Project Summary Electrical impedance myography (EIM) is a non-invasive technique for muscle evaluation that is finding increased application in a variety of neuromuscular diseases ranging from amyotrophic lateral sclerosis to muscular dystrophy to radiculopathy. In EIM, a weak electrical current is passed between two electrodes through a muscle of interest; two additional electrodes measure the resulting voltage patterns. Diseases impact the normal conductive and resistive properties of tissue, providing diagnostic information, as well as data on disease status, including progression or the effects of therapy. The development and application of EIM technology is the main focus of Myolex, Inc. The company has developed a convenient, compact EIM system, the mView?, that has been used in a number of academic, SBIR-funded, and pharma-supported clinical studies in both children and adults. However, the electrode sensor has not been optimized to ensure high quality data collection. There are two specific limitations. First, the existing electrode topology (i.e., the specific electrode size, shape, and inter-electrode distances) has been based mainly on intuition rather than on dedicated analyses. Second, the sensor is large, not cost-effective, and subject to high contact impedances due to limitations in the electrode material; in order to achieve good skin contact, it is necessary to repeatedly apply saline directly to the skin or probe, which leads to inconsistencies in the data. In this Phase 1 SBIR application, we propose to refine these structural and technical aspects of sensor design. In Specific Aim 1, we will utilize finite element models (FEMs) to assist in evaluating a variety of potential innovative sensor designs to identify those that most effectively interrogate a variety of muscles in adults and children. This modeling will study the effect of improved electrode spacing and variations in electrode size and shape. In Specific Aim 2, we will prototype a basic electrode array incorporating a hydrophilic foam material that we have already identified as providing high quality impedance data without artifact. This new array will use the improved electrode topologies of Aim 1. In Specific Aim 3, we will pilot these new arrays in 10 healthy adult subjects, 10 subjects with primary neurogenic disease, and 10 subjects with primary myopathic disease, evaluating specific quantifiable metrics, including repeatability, sensitivity to muscle condition, comfort, skin-contact artifacts, and diagnostic capability. At the conclusion of this work, we will be in a position to make a go/no-go decision as to the success of this effort and whether to pursue a Phase 2 application focused on making additional improvements to the mView system itself, including modifications to the impedance measuring unit. After this developmental effort is completed, we will test this refined system and sensors in a larger cohort of healthy and diseased individuals of all ages, including children. We will ultimately plan to seek FDA approval for this improved EIM system.