Nerve Conduction Studies and EMG

Nerve conduction studies and EMG

What is a NCS / EMG?
EMG or electromyography is a study of the electrical activity in muscles. We are able to look
at electrical activity in muscles at rest, and when they contract. We can identify if there is a
problem with the nerve supplying the muscle, or sometimes a problem with the muscle
itself, by looking at these signals.

Nerve conduction studies are usually performed along with EMG, to check the nerves
themselves are working normally.

What kind of conditions require EMG?

These are some examples of commonly referred conditions:

• Radiculopathy (pressure on the nerves coming out of the spine, sometimes caused by a prolapsed disc or bony protrusion)
• Peripheral neuropathy (damage to the nerves)
• Nerve injuries, e.g. following fracture or trauma
• Disease of the motor nerves causing weakness
• Myopathy (muscle disease)

How to prepare for the test

• It is essential for you to confirm that you can attend this appointment, within 5 working days, by calling us on 01905 733532 between 8am – 4pm Monday to Friday. Failure to do so may result in the appointment being re-allocated.
• Please let us know if you have a pacemaker or defibrillator fitted. Depending on the type, cardiology may need to monitor the pacemaker during the procedure.
• Please tell us if you are taking a blood thinner such as warfarin or apixaban prior to the test. If you are taking warfarin, please bring your record book and call us with your INR up to 1 week before the test, to ensure that it is stable and within the therapeutic range. The test can be performed on a blood thinner, but fewer muscles will be examined.
• Please tell us if you have a bleeding disorder, or are known to have low blood platelets. The test will not be performed if your blood platelets are less than 50,000/mm³; we will require a blood test 1 week before the examination to ensure that the platelets are at a safe level.
• Please do not use any moisturisers or creams on the arms or legs to be examined prior to the test, as the electrodes cannot stick to the skin sufficiently.
• Please wear loose clothing. If the arms are being examined, we will need to access the arm up to the shoulder. For the legs, we will need to access the leg up to the thigh. If this is not possible, you will be asked to change into a gown. You may be asked to remove jewellery on your hands or wrists.
• Please try to keep your hands and feet warm.
• Please take all of your medications as normal on the day of the test. The only exception to this is when you are referred for repetitive nerve conduction studies, and this is dealt with in a separate information leaflet. Please bring a list of all current medications with you.
• You may bring someone with you if desired, or they can wait in the waiting room.
• You should be able to drive or return to work following the test.
• Worcester Royal Hospital is a teaching hospital and there may be students observing or performing your test.

Directions to the department
The Neurophysiology department is located on Level 0 (River Level) at the Worcester Royal
Hospital. As you enter through the main entrance take the lift or stairs opposite down one floor.
The entrance to the department is in the lobby area opposite the River Court Restaurant.

Unfortunately, we cannot see people who are more than 20 minutes late. It can take a long
time to park, so please give yourself plenty of time to get here.

What to expect during the test
The test usually takes up to 45 minutes, depending on the referral question and how
widespread the problem is. Some appointment slots may be up to an hour. You will be asked
about your symptoms and medical history first, and a brief examination is performed. This
helps us to decide which tests need to be performed, to help with your diagnosis.

Nerve conduction studies are usually performed first, at the hands or feet. The skin is
prepared with an alcohol wipe. We stick recording electrodes to the skin and stimulate the
nerve using electrical pulses. A faint tapping is felt initially, which becomes stronger. This
may make your muscles twitch. Once a sufficient response is seen, the stimulus is stopped.
We look at the size and shape of the response, as well as the speed it is travelling, and
compare with our range of normal values. If you have a lot of swelling, it may be difficult to
obtain these responses and this will be taken into account when interpreting the results.

There are no lasting side effects from nerve conduction studies.

EMG is then performed, if necessary. A recording electrode is inserted into a muscle. This is
a fine needle. This feels like a small pinch and is well-tolerated by the majority of people
having the test. You can ask to stop the test at any time, if it becomes uncomfortable for you.
Recording is done while the muscle is resting, and you are then asked to move the muscle.
You may hear some noise and you will see some images on the computer screen, which
represent the electrical activity of the muscle. The needle is then removed and pressure
applied to the puncture site, before moving on to the next muscle.

The number of muscles required will vary depending on the question being asked by your
referrer. Typically, around 4 or 5 are sampled in one arm or leg if the problem is in one limb.

Most people will be told the test findings at the end of the test. Sometimes, the diagnosis is
not straightforward and more analysis is required.

Your referrer may need to look at other results such as blood tests and imaging before
coming to a diagnosis.

A report is typed and sent to your referrer, which normally takes up to 2 weeks.

Sometimes, you will be asked to come back for a repeat study in a few months’ time, to look
for any changes which will help with your diagnosis.

What are the risks?

• The most common side effect (more than 1 in 10 people) is mild discomfort or bruising after the test. This usually eases off after a couple of days.
• Less than 1 in 100 people may feel faint during the examination.
• Very rarely, there is a risk of infection due to needle insertion. This occurs in less than 1 in 10,000 cases. Sterile needle electrodes are used and the skin is wiped with a disinfectant wipe prior to insertion to minimise this risk. Needle insertion into a limb affected by lymphoedema is usually avoided.
• Very rarely, there is a risk of bleeding into the muscle requiring treatment. This occurs in less than 1 in 10,000 cases, and is usually seen in patients who take a blood thinner or have a bleeding disorder. Pressure is applied to the needle insertion sites, to reduce bleeding.
• EMG is safe in pregnancy.

Generally, EMG and NCS is a safe and well-tolerated procedure. If you have any particular
concerns that are not addressed in this leaflet, please feel free to call us to discuss before
your appointment on 01905 760697.

Further information about the test is available at:

www.ans.uk.org/tests
www.bscn.org.uk


If your symptoms or condition worsens, or if you are concerned about anything,
please call your GP, 111, or 999.

Patient Experience
We know that being admitted to hospital can be a difficult and unsettling time for you
and your loved ones. If you have any questions or concerns, please do speak with a
member of staff on the ward or in the relevant department who will do their best to
answer your questions and reassure you.

Feedback
Feedback is really important and useful to us – it can tell us where we are working well
and where improvements can be made. There are lots of ways you can share your
experience with us including completing our Friends and Family Test – cards are
available and can be posted on all wards, departments and clinics at our hospitals. We
value your comments and feedback and thank you for taking the time to share this with
us.

Patient Advice and Liaison Service (PALS)
If you have any concerns or questions about your care, we advise you to talk with the
nurse in charge or the department manager in the first instance as they are best placed
to answer any questions or resolve concerns quickly. If the relevant member of staff is
unable to help resolve your concern, you can contact the PALS Team. We offer informal
help, advice or support about any aspect of hospital services & experiences.

Our PALS team will liaise with the various departments in our hospitals on your behalf,
if you feel unable to do so, to resolve your problems and where appropriate refer to
outside help.

If you are still unhappy you can contact the Complaints Department, who can investigate
your concerns. You can make a complaint orally, electronically or in writing and we can
advise and guide you through the complaints procedure.

How to contact PALS:
Telephone Patient Services: 0300 123 1732 or via email at: [email protected]

Opening times:
The PALS telephone lines are open Monday to Friday from 8.30am to 4.00pm. Please
be aware that you may need to leave a voicemail message, but we aim to return your
call within one working day.

If you are unable to understand this leaflet, please communicate with a member of staff.

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