Nerve conduction studies (NCS) and electromyography (EMG)

This leaflet is designed to inform you about the investigation for which you been referred. We hope it reassures you. We have a team experienced in these investigations; you will have the opportunity to discuss questions or concerns before the investigation begins.

Consent

We must obtain your consent for any procedure or treatment beforehand. Staff will explain all the risks and benefits before they ask for your consent. If you are unsure about any aspect of the procedure or treatment proposed, please do not hesitate to ask them for more information.

About NCS and EMG

The term 'EMG' is often used by clinicians to refer to both nerve conduction studies and electromyography.

These studies test the function of the larger nerves in arms and legs, and the muscles that are connected to them which make them work.

• Applying small pulses to the nerves from the skin allows checking that the nerves are working as they should.
• A very fine needle, like an acupuncture needle, is placed to test muscle function.

What happens before the investigation?

No special precautions are required. It is helpful if you wear loose fitting clothing, as we generally need to examine your arms or legs. Please avoid using moisturising creams on the day of the test, as they can interfere with the recordings.

At the time of testing please tell us about any of the following:

• If you have a pacemaker or implanted cardioverter or cardiac defibrillator
• If you are taking warfarin or other blood thinning medication
• If you have an increased risk of bleeding or infection

We can usually still perform tests in such situations, but we may need to modify what we do.

What do I need to do on the day of the test?

• There is no restriction on eating or drinking either before or after the investigation.
• There is no restriction on driving after the test.
• Please continue taking any medication you are prescribed. It would be helpful to bring a list of your current medications with you.

What happens during the test?

Nerve conduction studies (NCS)

Nerve conduction studies are generally performed first. Small sticky electrodes are stuck to the skin to measure the ability of your nerves to conduct electrical signals. A brief electrical pulse is applied to the nerve from the skin surface and the response is recorded. During this you might feel a localised tapping sensation. We record the size, shape and speed of responses from nerves that go to supply muscles and the skin.

Electromyography (EMG)

Sometimes the doctors also need to perform EMG (pictured at the top of this leaflet). They insert a very fine sterile needle electrode into the muscle to record the activity when the muscle is tensed. No electrical stimulation is used for EMG. The electrode is very thin, like an acupuncture needle, and is used only once so it cannot pass on any infection. You might feel a scratch when the electrode is inserted; the team are experienced in making this as painless as possible.

Special note: assessing children

We commonly see children, including babies, for NCS and EMG assessment. Parents generally hold their child on their lap or sit with them, depending on their age. We commonly use distraction techniques, and find that most children complete the test without difficulty. We have an expert team and are experienced in assessing children. Of course on some occasions we make the test very brief, or stop if required. The investigation takes place in a calm room and we can easily adapt what we are doing depending on the situation. It may be helpful to bring some of your child’s favourite toys.

Please note, however, that we have no provision to supervise any additional accompanying children to be supervised whilst you are having your NCS/EMG.

There are two neurophysiology departments. One of these is on level 3 of the main Outpatients building; the other is located in Clinic 33 of the Addenbrooke’s Treatment Centre. Please check your letter carefully for details on where your appointment will be and use the maps in this leaflet to guide you. Additional information on getting to Addenbrooke’s is available on our website.

Please note: if you arrive more than 30 minutes late for your appointment, you may not be seen.

Please contact us if you are travelling via hospital transport as this may determine the time of your appointment. Unfortunately, we are unable to see patients on beds or on stretchers in our outpatient department; please call us if this affects you.

Who will be present?

A healthcare scientist or a neurophysiology doctor will perform the test. A partner, family member or friend is very welcome to accompany you during the test. If you would feel more comfortable with a healthcare scientist or consultant of a particular gender or would like a chaperone, please call us before attending to let us know.

Addenbrooke’s is a teaching hospital; you may be asked if you would consent to trainee staff performing the test under supervision or if you would mind other healthcare professionals/students observing the test. Refusing consent for this will not affect the test.

How long will the test take?

The consultation usually takes about 30 minutes but can sometimes last around an hour. Electrical testing is only part of this time.

Risks

Nerve conduction studies are very safe. They can be performed on patients who have pacemakers.

After EMG, the muscle may feel slightly itchy, or ache for a few minutes, and you may notice a small bruise. It is a very safe procedure, with significant complications due to bleeding very rare (less than one in 10,000). We may limit or adapt the EMG in some situations, for example if you are taking blood thinning medications.

Overall, complications are very rare, and if we consider the risks to be higher than normal we will discuss this with you and seek your consent about how to proceed.

You can return to your normal activities, including driving, immediately after the investigation. There is no restriction on testing during pregnancy. Should you be concerned about pain, swelling or bruising after a test, please contact us, or your GP.

When do I get the results?

The results will not be available on the day of the recording. The healthcare scientist and doctor will review the test and will prepare a detailed report for the consultant who referred you. The results will be sent to your referring consultant within two weeks – sooner if urgent. It is best to discuss these results with the consultant who referred you, as they will need to be explained alongside any other tests that have been performed.

Contacts/ Further information

If you need any further information or have any other queries please contact the neurophysiology administrator by phone on 01223 217136 Monday to Friday 08:30 (8:30am) to 17:00 (5pm) or by email.