Electordiagnostic Medicine in Myopathy

J Korean Assoc EMG Electrodiagn Med 2001;3(2):53-57.
Published online May 10, 2001.

Abstract

The electrodiagnostic evaluation of suspected myopathic process can be quite challenging even for the most experienced practitioner given the different types of myopathic disorder. The values and limitations of the electrodiagnostic examination in assessing patients with possible myopathies are discussed. Limitations include: 1) no findings are specific for muscle disease; 2) the particular changes may be quite diverse; 3) myopathies of different etiologies may have the same presentation, whereas the same myopathy may have different presentations at different time; 4) a specific myopathy cannot be diagnosed; and 5) the ability to diagnose myopathy may be seriously compromised by the presence of certain disorders. Benefits include: 1) wide spread muscle sampling; 2) help in determining most appropriate muscle for biopsy; 3) ascertaining to some extent, the type of myopathy present, depending on the particular findings; 4) distinguishing entities often confused clinically with myopathies; 5) recognizing abnormalities otherwise undetectable. The combination of nerve conduction studies and needle EMG may determine that the patient has a disorder affecting the anterior horn cells, peripheral nerves, or neuromuscular junction as opposed to a myopathy. Of particular importance with myopathic disorders, the electrodiagnostic examination is only one portion of the total work-up for a patients with a possible myopathy.

Key Words: Myopathy, Electrodiagnostic medicine, Nerve conduction studies, Needle EMG