A test to help assess the function of the nerves in the arms and legs.
What is NCS?
It is a test to help assess the function of the nerves in the arms and legs. You will have NCS and then depending on the results you may need to have an EMG (electromyography).
Preparation for the test
- You should eat and drink as normal prior to the test
- Continue to take medications as prescribed (however, if you are taking blood thinning tablets, such as Warfarin, you should let the staff know on arrival for your appointment).
- If you have a pacemaker/implanted device with cardiac defibrillator fitted you MUST telephone the department to discuss this as it may affect how the test is performed.
- Please wear clothing that can be easily removed or rolled above the elbows or knees. On the day of the test please remove all jewellery from your hands and leave it at home.
- Try to have hands and feet as warm as possible and avoid using lotions or creams for at least 24 hours prior to the test
- Bring a list of current medications.
- The test can last up to one hour.
How is it done?
The test is performed by a physiologist and/or a consultant neurophysiologist and takes approximately 60 minutes. It involves attaching electrodes to the appropriate limbs to record the response from nerves. Other electrodes are used to stimulate nerves. This involves delivering a small electrical impulse to the skin. There is a slightly uncomfortable sensation but only lasts for a few seconds at a time. This may result in twitching of the muscles. This only affects the nerve in a small controlled area. It will not affect the heart. Several nerves may need to be assessed. There are no after-effects from this test.
Back to topWhat is an EMG?
Not all patients will require an EMG following the nerve conduction tests. An EMG is the recording of the electrical activity that is naturally produced in your muscles. The test will be performed by a consultant neurophysiologist.
A fine needle is used for this test, and although a sharp scratch is felt as the needle is inserted, the majority of our patients do not consider this test to be unduly uncomfortable. This allows the electrical information to be assessed on a screen. Several
muscles may need to be tested during this examination. The muscles tested may feel sore for a short time after the test. The needle(s) may cause a small amount of bleeding and there is a chance of localised bruising. You will be able to drive after this procedure.
If you have a pacemaker/implanted device with cardiac defibrillator fitted you MUST telephone the department to discuss this, as this may affect how the test is performed.
What is a single Fibre EMG?
Single Fibre Electromyography is a very good test to assess the function of the neuromuscular junction – the connection between the nerve and muscle. The benefit of single fibre EMG is that it can assess types of muscle weakness or fatigue (tiredness) when other tests have been inconclusive.
How is it done?
- This special test will be performed by a doctor usually after the routine nerve conduction study. The whole procedure may take around 1 ½ hours to complete and a double slot appointment will be given.
- You will be asked to lie down and relax. A very fine needle electrode will be placed into the muscle in your forehead or beside the eyebrow. The needle will stay in place for the duration of the test to record activity from the muscle or may be moved to record from different sites. The doctor will ask you to look up or down or frown slightly and maintain this position while they assess how the muscle is working. The better you are able to cooperate with the test, the shorter time it will take.
Preparing for the test
If you are taking Mestinon – Pyridostigmine, you will need to talk to your doctor about the safety of stopping them for at least 12 hours prior to the test or as a minimum the night and morning before the test. This is because if you have taken Mestinon/ pyridostigmine, it may affect the result of the test.
Please try and make sure your hands and feet are warm for the test by wearing gloves and socks. Cold temperature can affect the result of the test.
You will need to inform us if you had history of botox (botulism toxin) injection to any part of your facial muscles as this can affect the result of the test.
After the test
The muscles tested may feel sore for a short time after the examination. The needle(s) may cause a small amount of bleeding and there is a chance of localised bruising. You will be able to drive after this procedure. You may take your morning dose of Mestinon or Pyridostigmine after the single fibre EMG is finished so, please bring it with you.
Test results
All results will be analysed by a consultant who specialises in neurophysiology. The report will not be available immediately but should reach your GP/Consultant within 7-14 days.
Contact Details
If you have any queries or questions regarding this information, or require a large print version please contact the Neurophysiology Department on the number below:
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