About Your Electrodiagnostic Test
Each evaluation begins with a history and neurological examination by a highly-trained, experienced, board-certified neurologist who specializes in nerve and muscle disorders. The electrodiagnostic test consists of two parts: (1) the nerve conduction velocity test (NCV or “nerve conduction study”) and (2) the needle electromyogram (“EMG”). The NCV tests how well a nerve sends electrical signals. The EMG measures the electrical activity of muscle. These tests help us evaluate symptoms such as numbness, tingling, pain, weakness, fatigue and cramping, and allow us to assist your health care provider to accurately diagnose your condition and determine the best treatment for you.
On the day of your test
Before your test, the doctor will tell you about the test and what you can expect to happen. Each test is unique and tailored to the individual patient, so the doctor can give you an estimate of how long the test will take, but that may change depending on the findings as the test progresses. What you feel or hear during the test does not indicate the severity of your condition, so you do not need to worry about comparing things or describing what you are feeling during the test.
This is a technical study and involves many measurements and calculations. The doctor will be paying careful attention to the testing process and at times may be intently focused on the NCV/EMG machine. Don’t worry if the doctor is not very talkative. The focus is still on you!
Nerve conduction velocity (NCV) tests
A nerve conduction velocity test is a study of nerve function. Nerves are like small cables that connect the brain and spinal cord with the rest of the body. Nerve damage can cause pain, tingling, loss of sensation and weakness. Nerve conduction studies allow the doctor to study the electrical signals along the nerves determine where the problem is located.
The doctor will place small painless metal discs (electrodes) on your skin, held in place with hypoallergenic medical tape, or use stickers (like an EKG). Points will be marked where the nerves will be stimulated. You will be asked to hold the extremity being studied in certain positions (for example, palm up or elbow bent). The nerve is then stimulated with small electrical shocks delivered to the surface of the skin. These shocks are very brief (a fraction of a second) and feel something like the electric shock from touching a metal doorknob after walking on carpeting. After stimulation, the nerve responds by sending its own signal. This signal is recorded the computer and analyzed by the doctor. These small shocks have no lasting effects and cannot cause any harm. There are no side effects from having a nerve conduction study.
Several nerves will be studied depending upon the location and type of symptoms you are experiencing.
Our doctors have had this test themselves and know what it feels like, so they work as quickly and carefully as possible. Our doctors have performed tens of thousands of nerve tests over the last 25 years.
Electromyography (EMG) tests
The EMG records the electrical activity muscle, allowing us to learn a lot about muscle and nerve function. A very small, thin needle is inserted through the skin into the muscle. It is the same size needle used by diabetics to give themselves insulin shots. A new sterilized needle is used on each patient and is thrown away after the test. The needle records the electrical signals inside the muscle and sends these to the computer. The doctor will analyze the waveforms on the screen and sounds generated by your muscle. Don’t be alarmed by the sounds that you hear – it’s part of the test. Being stuck by a needle, even a tiny one, is not very comfortable, but our doctors will do it as quickly and easily as possible.
Preparing for your test
Please avoid using skin creams, lotions and moisturizers on your arms and legs 24 hours prior to your appointment.
Please tell the doctor if you are on any blood thinners (such as Coumadin (Warfarin), Eliquis, Xarelto, Pradaxa) or have a blood clotting or bleeding disorder or have a pacemaker or any implantable device in place. These conditions generally do not prevent the test from being performed but are important for the doctor to know about.
Let the doctor know if you have a latex allergy so that latex-free gloves can be used. In the past, people who had to take antibiotics prior to dental procedures (usually for heart valve conditions) also took antibiotics for EMG tests. However, current standards do not require prophylactic antibiotics. You might think of it this way: if you would take an antibiotic if you stuck yourself with a small sewing needle, then you should take an antibiotic if you have an EMG test; otherwise, antibiotics are not necessary.
You may eat, drink and take your medications, including pain medications, before and after the test.
After your test
There are no restrictions after the test. You may drive, return to work, shower, swim, and any other normal activity after your test.
Our doctors will analyze your test results and fax a report to your doctor on either on the same day or within 24 hours. You should follow up with your referring doctor for your test results and further recommendations.