Nerve excitability testing and its clinical application to neuromuscular diseases

Non-invasive nerve excitability testing measures the membrane polarization, ion channel function and paranodal/internodal condition of peripheral nerves. This technique has been recently used for various neuromuscular disorders, such as pure motor conduction block in multifocal motor neuropathy, conduction block in carpal tunnel syndrome and Na(+) channel function disorders in diabetic neuropathy, to shed light on their pathophysiology. Here, we review the basics of ion channel functions and membrane properties that influence nerve excitability, the basic principles of nerve excitability testing and the reported findings in various disorders.