What are the clinical indications for an EMG?
An EMG should be ordered to determine the localization and severity of a suspected neuromuscular disorder. The NCS and needle EMG are almost always performed together in reputable laboratories. Testing can distinguish between neurogenic (nerve or neuron-related), myopathic (muscle-related), and neuromuscular junction disorders. In neurogenic conditions, testing can often distinguish between disorders primarily affecting myelin (i.e., demyelinating neuropathies) and axonal or neuronal disorders. An EMG is generally not useful in the assessment of brain or spinal cord disease. In order to get the most useful information from the test, the requesting physician should indicate his or her clinical question or concern as specifically as possible. It is not usually necessary to request particular procedures (e.g., NCS, repetitive stimulation, needle EMG) as a qualified electrodiagnostic consultant can decide what is needed to answer the clinical question.