Muscle velocity recovery cycles: a new tool for characterization of muscle disease in vivo

PD Dr. med. Werner J. Z'Graggen, Inselspital Bern


The typical diagnostic sequence in a patient with suspected myoptahy consists of taking patient history, clinical examination,laboratory investigation and needle electromyography. Findings are often rather unspecific and a large number of patients have to undergo further invasive and expensive diagnostic procedures such as muscle biopsy and genetic testing.
We have recently developed amethod of measuring muscle velocity cycles (MVRCs) that provide information about muscle membrane properties such as membrane potential. This method is simple to perform, cheap in costs, minimally invasive, independent of patient's cooperation and has a good repetability. In our first studies we have already demonstrated a good clinical applicability of the method for three distinct types of myoptahy: Andersen-Tawil Syndrome, critical illness myopathy and uremic myopathy. We have provided new insights into the changes of muscle membrane potential and pathopysiology of these myopathies.
The general aim of the proposed research project is to use measurement of MVRCs to investigate the changes in muscle membrane properties of the more common hereditary, metabolic and toxic myopathies. Therefore, representative myopathies of the group of channelopathies, myotonic dystrophy, endocrine and toxic myopathies will be studied. This project aims to broaden the clinical use of this method, to evaluate its potential role in helping hysicians to recognize and distinguish myopathies, and to guide them inthe selection of future diagnostic steps (muscle biopsy, type of DNA testing). It will also help to improve our understanding of the pathophysiology of distinct myoptahies.