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Dr Diana Andreeva
1. What are NCS and EMG?
EMG (Electromyography) usually refers to both Nerve Conduction Studies (NCS) and EMG. Depending on the problem being investigated, you may require one or both of the procedures described below. NCS are used to test the functioning of the peripheral nerves in your hands, arms and/or legs. EMG testing is used to test the electrical activity within the muscles to help determine if weakness is caused by nerve damage or muscle disease. These tests are used to investigate a number of different muscle and nerve problems and will assist your Consultant in the diagnosis and management of your medical complaints or condition.
2. Why have an NCS/EMG test?
NCS are done to:
∑ Detect and evaluate damage to the peripheral nervous system.
∑ Identify the location of abnormal sensations, such as numbness, tingling, or pain.
EMG is done to:
∑ Diagnose diseases that damage muscle tissue, nerves, or the junctions between nerve and muscle (neuromuscular junctions).
∑ Evaluate the cause of weakness, paralysis, involuntary muscle twitching, or other symptoms.
Measuring the electrical activity in nerves and muscles can help detect the presence, location, and extent of diseases that can damage nerves or muscle tissue. In case of nerve injury, the actual site of nerve damage can often be located. NCS and EMG are usually done together to provide more complete information.
3. What should I do before the NCS/EMG test?
Take a bath or shower to remove oil from your skin on the morning of the test. Do not apply any skin lotions/ moisturisers /cremes on the day of the test. Wear loose fitting clothes that enable you to roll the sleeves up to the armpit or trousers above the knee.
Eat normally on the day of your test.
Take all your usual medication as normal. Bring a list of your medications with you. Inform the doctor if you have a pacemaker or any other cardiac devices; or you are taking warfarin, heparin or another tablet to thin your blood.
rings (if possible)
before the test .
4. What happens during NCS/EMG test?
Before performing the NCS/EMG you will be explained each aspect of the test and answered any questions you may have. Test is done while lying on a bed or sitting in a reclining chair.
NCS: A number of sticky electrodes are placed on your hands or feet which can be easily removed afterwards. To test the nerve a small electrical pulse is given to the skin and your reactions are recorded. This is repeated at 2 or 3 points along the arm or leg. The electrical stimulation can be a little unpleasant, but should not cause too much discomfort. The corresponding nerves on the other side of the body may be studied for comparison. Depending on NCS results you may also have EMG.
EMG: The skin over the areas to be tested is cleaned with an antiseptic solution. A fine sterile electrode (like an acupuncture needle) is inserted into the specific muscle to be tested. The electrical activity in that muscle is recorded while the muscle is at rest, when contracting gently, and when contracting forcefully. The needle may be repositioned a number of times to record the electrical activity in different areas of the muscle or in different muscles. When the testing is completed, the needle is removed and those areas of the skin where a needle was inserted are cleaned. This takes a few minutes for each muscle. The procedure may sound worse than it actually is and causes only minor discomfort.
Duration: Depending on the complexity of the problem, the study may take anywhere from 20-60 minutes or more.
5. What happens after the NCS/EMG test?
When the investigation is finished, the electrodes are removed without any pain.
You will then be able to go home or back to work and continue with your normal activity.
NCS do not have any side effects. After EMG the muscles into which the needle has been placed may ache a little for a few minutes. There may be the occasional small bruise.
The results are not available immediately. The report is then sent to you by email within 3 working days or you can pick up it from registration office.
6. How will the results of this test assist my consultant?
An NCS/EMG will help your consultant in the diagnosis and management of your complaints or condition.
You have to discuss the report/finding with your consultant.
7. What are the consequences of not having NCS/EMG?
NCS/EMG is well established method of helping doctors to diagnose and treat a range of medical conditions.
Your doctor would not have as complete a picture as they require and hence your diagnosis may take longer and/or your treatment may not be the most appropriate.
8. Are there any alternative ways of getting the same information that an NCS/EMG provides?
∑ No. However, there are many areas of research taking place and in the future different methods may be available.
9. Frequently asked questions
May I eat beforehand? Eating is fine.
Will I be able to drive alone after the test? Yes.
Will I feel anything? NCS: Most people say that the electric pulse is not painful, but that they feel an unusual sensation such as tingling or pulsing. EMG: A fine needle is used for this test, and, although a sharp scratch is felt as the needle is inserted, the majority of the patients do not consider this test to be unduly uncomfortable.
Should I stop taking my medication/tablets before the test? Do not stop taking any of your medication unless you have been told to do so by your Consultant. However, if you are taking blood-thinning tablets such as Warfarin you should tell the doctor before the test starts. It would be helpful if you would bring a written list of your medication with you.
Are there any after-effects? NCS: No. EMG: The muscles tested may feel sore for a short time after the examination.
Are there any risks? There are no reported risks.
If you have any further queries or concerns, you will have the opportunity to discuss same on the day of your appointment prior to the start of the test.
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Revised: 07 October 2014