What is an EMG?
Electromyography (EMG) is a diagnostic procedure used to assess the health of muscles and the nerves that control them. Electrical signals travel along the nerve and cause the muscles to contract. An EMG translates these signals into waveforms, sounds and numerical values that a physician will interpret to diagnose conditions that can cause numbness, tingling or weakness.
Who performs the EMG?
A physician who performs EMGs has graduated from medical school and has completed four years of training in a residency program such as physical medicine and rehabilitation (PMR), or neurology. Medical training helps the doctor decide which tests to perform based on your symptoms. In our practice, a board-certified PMR physician performs the EMG.
Why am I having an EMG performed?
You have been referred to have an EMG performed because you have numbness, tingling, pain, weakness, or muscle cramping. Some of the tests that the doctor may use to diagnose your symptoms are nerve conduction studies, needle EMGs and evoked potentials. Valley’s PMR physician will examine you to determine which tests to perform.
What is a nerve conduction study?
This study tests how well signals travel along a nerve and can help find the cause of abnormal nerve function. Surface electrodes are placed on the hands or feet. To test the nerve a small electrical pulse is given to the skin and a measurement is taken. The small electric pulse causes a short, mild tingling feeling. This is repeated at two or three points along the arm or leg. This is to measure the speed and strength of signals traveling between two or more points.
What is a needle EMG?
An EMG can reveal nerve dysfunction, muscle dysfunction or problems with nerve-to-muscle signal transmission. A fine needle or pin is inserted into a muscle. Recordings are taken with the muscle relaxed (at rest) and when the muscle is tense (contracted). This takes a few minutes for each muscle. The doctor will interpret the waveforms and sounds transmitted to assess for any abnormalities. The needles are discarded after use to prevent transmission of infection. You may experience some temporary, minor bruising where the needle electrode was inserted into your muscle. This bruising should fade within several days. If it persists, contact your primary care doctor.
How should I prepare for the test?
Please wear comfortable, loose clothing on the day of the examination. You may be asked to change into a hospital gown for the procedure to properly assess the area of concern. Avoid applying lotion, cream, or oils to the skin the day of the procedure. Please take all medications as prescribed by your referring physician. Please notify us and the referring physician if you are taking aspirin, any blood thinners (Coumadin, Plavix), have a pacemaker or have hemophilia the day the appointment is made.
What should I expect during the procedure?
During the nerve conduction study, you may experience a twinge or spasm as the physician is stimulating a particular nerve. During the needle EMG, the needle electrode may cause discomfort or pain that usually ends shortly after the needle is removed. The needle EMG tests the muscle during relaxation and during a slight contraction. The physician will give you instructions on relaxing and contracting the muscle. If you’re concerned about discomfort or pain, you may want to talk to the physician about taking a short break during the exam.
How long will the test take?
The test on average takes about 20 to 60 minutes. The length of time of the testing depends on where you are experiencing your symptoms (one or two extremities).