Nerve studies (NCV/EMG)
This procedure involves two parts. The first part is called Nerve conduction studies. It could be done in the upper and/or lower extremities. Your referring physician or the physician doing the study might determine the right combination of extremities to be examined based on your symptoms.
Usually during nerve conduction studies, electrodes are placed on your hands or feet, and then small electric shocks are delivered using hand held device. It stimulates the nerve being tested and contracts the muscle where electrode is placed. Those electrode transmits the response and the software in the computer records it as waveform. These are further analyzed to determine the strength of the response and velocity of the current traversing through the nerve examined. Combination of the responses in various nerves are then studied by the neurologist specializing in this procedure to determine the pattern of abnormalities and help arrive at the diagnosis.
Although it seems scary to be shocked, the amount of the current delivered are mild. There is safety inbuild in the programming. It is not a pleasant experience though most patients can get through the procedure with minimal discomfort.
The second part of the test is Needle Electromyography. The physician performing the test will insert needle into few muscles in your upper and lower extremities. You will be asked to perform certain maneuver to help contract the muscle. The needle has inbuilt electrode which will record the electrical signal from the muscles and transmit to the software. The physician performing the procedure will be able to see the waveforms and hear them as well. Those signals are analyzed to further determine the pattern of any muscle damage.
Again, it might feel scary to have needles inserted but the needles are quite thin. Inserting needle can cause mild pain, though most patients are able to tolerate it.
Nerve conduction studies and needle Electromyography (EMG) are low risk procedures, and complications are rare. There’s a small risk of bleeding, infection and nerve injury where a needle electrode is inserted.
We recommend that you do not apply any kind of lotion or cream or oil on the skin. Consider having shower before the test and do not apply any oil or lotion after that. Dress comfortably and wear loose clothing that permits access to the limbs. Inform the physician if you are taking any blood-thinning medications, or have any bleeding disorders or have pacemaker or external devices installed.