Electromyography (EMG) /Nerve Conductions Studies (Electrodiagnostic Medicine)

Electromyography (EMG) /Nerve Conductions Studies (Electrodiagnostic Medicine)

Numbness, tingling, pain, weakness, and loss of muscle bulk may indicate a nerve impingement or a nerve irritation. While x-rays, CT scans, and MRI scans are useful in producing a picture that you doctor can use to infer the possibility of a nerve impingement or a nerve irritation. These tests do not actually demonstrate what is actually going on with the nerve itself. In addition, x-rays, CT scans, and MRI scans are often non-specific and may demonstrate multiple abnormal findings, each of which may be capable of being the source of numbness, tingling, pain, weakness, and loss of muscle bulk. EMG/NCS is a useful test that can be used to complement the information obtained in a history, the physical examination, and tests. Conditions commonly diagnosed with the use of EMG/NCS include carpal tunnel syndrome, cervical radiculopathy (nerve root impingement or irritation in the neck), and lumbar radiculopathy (nerve root impingement or irritation in the lower back).


Electromyography (EMG) involves a very thin needle or wire electrode that is placed into your muscle. By observing the activity on the screen as well as listening to the activity, this test is used to detect current or past irritation or impingement of the nerve, a problem with the nerve to muscle junction, or a problem with the muscle itself.

Nerve Conduction Study (NCS) involves small shocks using a stimulating electrode and measured by recording electrodes. This test measures how quickly your motor and sensory nerves are conducting messages from one point to another.

This procedure is performed by a physician trained in electro-diagnostic medicine.


Your doctor has recommended that you undergo EMG/NCS. This will be performed as an outpatient procedure in an office setting. You may drive to and from the testing. There are no restrictions in regards to your eating before or after the testing.

Please give the physician performing your examination a list of medications you are currently taking. For the most part, you should not stop your medications in preparation for this test. If you are on pain medications, you should continue the pain medications prior to the test. A few medications, however, do have a small potential to alter the results of this test, and the physician performing the test needs to know.

Please take off your jewelry and watches and secure them in your clothing or bag.

Do not apply any lotion or ointments on to your skin on the day of the testing. If you use any types of lotion or ointment on any part of the body to be tested, please wipe it all off with soap and water and dry thoroughly. Lotions or ointments on the skin make the procedure difficult to perform and may invalidate results. If you are having your upper limbs studied, please take off your shirt and place the gown on with the back open. If you are having your lower limbs studied, please take off your pants or skirt, shoes, and socks or hosiery and place the gown on with the back open. Please keep your undergarments on. If you are not sure which part of your body we will study, take off everything except your undergarments and place the gown on with the back open.

If you have cold limbs, let your physician know. It is very important that your limbs are warm. Cold limbs may invalidate results. This test may take anywhere between 30 minutes to an hour or more. In some instances, it may be necessary to have you return at another time to complete the examination.

Relax. This test will provide useful information in regards to your condition. Your being relaxed will allow the test to be performed with greater ease, and we will be able to finish earlier. Following the testing, the physician performing the test will usually be able to give you the preliminary results of the testing.


There are no risks associated with nerve conduction studies. Nothing is inserted into the skin, so there is no risk of infection. The voltage of electrical pulses is not high enough to cause an injury or permanent damage. There is a theoretical risk that if you have a cardiac defibrillator, the shock from the nerve conduction study may activate it. If you have a cardiac defibrillator or a pacemaker, notify us before the examination.

Electromyography (EMG) is very safe. With the EMG, you may develop small bruises or swelling at some of the needle insertion sites. If you take blood thinners, such as Coumadin, the risk of bleeding and bruising may be greater. If you have a bleeding disorder, such as hemophilia, we may not be able to perform parts or the entire test. Please notify us if you are on a blood thinner or have a bleeding disorder. The skin is sterilized with alcohol pads, and sterile, single-use, prepackaged wire electrodes are used and discarded after each and every examination, so infections are extremely rare.


During the test, the physician will mark on your skin with a ballpoint pen to facilitate measurements. The ink wipes off easily with alcohol pads. You may ask the physician for some alcohol pads after conclusion of the examination.

Following the testing, the testing physician will be able to discuss the results of this test with you.

You may feel some mild soreness following the examination. Should this occur, the best way to address this is to use ice over the affected area for up to 10 minutes at a time. You may repeat this every hour. Do not do this, however, if you have diabetes or have peripheral blood vessel disease. Even if you do nothing, the soreness or bruising will resolve spontaneously and completely within a few days.

Remember, this test is meant to help you and to give you answers. If you have any questions, feel free to ask the physician performing the test.

Pre and Post Instructions

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