Electrodiagnostic studies are used to measure certain types of electrical activity, particularly action potentials of muscle, nerve and brain tissue. An action potential is a “spike” of electrical discharge that travels along the membrane of a cell and carries information between cells such as muscles and neurons. Electrodiagnostic studies can measure communication between these cells suggesting particular types of nervous system disease including muscle (myopathy), nerve (neuropathy) and brain (encephalopathy). In addition, certain electrodiagnostic tests can be used to screen for deafness.