What is Electrodiagnosis?
Electrodiagnosis is a direct extension of the neurologic portion of the physical examination. It is helpful in evaluating the causes of numbness, tingling, weakness, and muscle cramping. The testing consists of two parts, but either may be done without the other in certain cases.
PM&R trained physicians and neurologists have special training in performing these tests. The testing usually takes 30 to 60 minutes. There are no restrictions on activity before or after the testing.
1. Nerve Conduction Studies (NCS)
This allows a physiologic test of how well signals are transmitted along nerve pathways in the extremities. Small electrical pulses are applied to the nerve through the skin and the resultant signal is recorded at another site along the path of the nerve. The speed, size and shape of the signals are measured. When a nerve is damaged the signal may be slower, smaller or absent.
2. Needle Electromyography (EMG)
This portion of the testing looks at electrical signals within muscles. A very small diameter needle is inserted into a muscle and the signals are measured at rest and during contraction of the muscle. The size, shape, quantity and quality of signals are measured. With nerve or muscle impairment the signals with be altered in form, quantity or sound. The results of the testing are used to determine if any nerve impairment is present, and to localize the site of impairment if present.
3. Special Precautions
You should inform the physician or staff if you are on blood thinners, have hemophilia or other bleeding disorder, have a pacemaker, or any active infections. Please avoid using skin lotions on the day of testing.