Please read this information carefully before coming in for your Nerve Conduction Study (NCS) and/or Electromyography (EMG).
What is an NCS?
NCS stands for nerve conduction study. It is a test that assesses the function of the sensory and motor nerve pathways, allowing us to see how the nerves are working. It is a non-invasive procedure, that records the electrical activity from the nerves in response to a series of small electrical impulses.
Why do an NCS?
If you are experiencing numbness, weakness, or other changes in sensation to your hands or feet you may be referred for a NCS to see if there is evidence of a trapped nerve.
What happens during an NCS?
At the start of the test, contact sites on your hands and feet will be wiped with alcohol gel to ensure a good contact with the recording discs.
The NCS is split into 2 tests.
First the sensory nerve pathways will be tested. Some stimulating rings will be applied to the fingers, or a recording bar will be used on your feet. Sticky pads to record the responses will also be applied to your skin.
Once everything is attached you will feel small electrical impulses from the rings on your fingers. The series of impulses will continue for several seconds, and the responses will be recorded on the machine. The rings will then be removed.
During the second part of the test the motor pathways will be tested. The sticky recording pads will be moved to different areas of the skin. A stimulating bar will then be applied, and you will feel the small electrical impulses once again and this time cause some twitching of your fingers and arms (if recording from your upper limbs), and legs and toes (if recording from your lower limbs).
The series of impulses will continue for several seconds, and the responses will be recorded on the machine. Once the test is over all the sticky pads will be removed and your skin wiped and cleaned.
What is an EMG?
EMG stands for electromyography. It is a test that assesses the function of individual muscles, allowing us to see how they, and the motor nerve pathways which control them, are working.
Why do an EMG?
If you are experiencing numbness, tingling, cramping, or unexplained muscle weakness you may be referred for an EMG to see if there is evidence of a muscle disorder or nerve damage affecting the muscles.
What happens during an EMG?
An EMG will be done after the nerve conduction study. A fine needle is inserted into the muscle being examined and then the response will record while the muscle is resting, during slight activity and when fully active. To do this, you will be asked to slightly flex the muscle which will produce crackling sounds on our machine, the clinician will then ask you to fully flex the muscle to which will cause louder crackling sounds.
This may be repeated on several different muscles depending on the reason you are having the test.
The test can vary from 30 minutes to an hour, although occasionally it may take longer. Because of this we cannot guarantee that you will be seen exactly at the time of your given appointment. We do try to keep to the appointment system, so please attend in good time.
Preparing for the test
- Wear loose fitting clothing with easy access to your upper arms and legs when stimulating the nerves.
- Do not apply moisturising products to your hands and feet before the test as these can affect our ability to record responses.
- Continue taking all regular medication and eat as normal before the test.
- Please inform the department before attending if you are have from an infectious condition, a bleeding disorder, take warfarin (or other anti-coagulant medications), or have a cardiac pacemaker fitted.
- You will be asked if you understand this information and whether you consent to the test before we start. At your appointment you are welcome to ask the neurophysiologist doing the test to give you further information or to explain more about the procedures.
When will I get my results?
You will not get your results straight after the test or see a doctor on the day as the NCS and EMG need to be fully analysed.
A full report will be sent to the GP or consultant who referred you within 2 weeks, they will then contact you to discuss the results. Please note, results are not sent directly to you.
Contact details
This information is intended as a guideline only. If you have any further questions about your test (excluding about results) please contact the department on the numbers below and a member of staff will be happy to help.
Your responsibility as a patient
Outpatient services at North Bristol NHS Trust are in great demand. Even so, every week an average of 600 patients fail to attend, which wastes appointments. Please tell us with as much notice as possible if you no longer need your appointment and we can allocate this to another patient.
What if I am unwell or need to change my appointment?
If you have an infectious condition, such as COVID-19, measles, mumps, chickenpox, flu, stomach upset, have head lice, or are unable to attend your appointment for any other reason, please let us know with as much notice as possible so that your appointment can be rescheduled and offered to someone else.
If you want to change the appointment for a second time, we cannot offer you another date unless there are exceptional circumstances.
What if I don’t attend?
We will assume that you no longer require your appointment, and we will not offer you another one. We will write to the consultant/doctor who referred you and inform them that you did not attend.
© North Bristol NHS Trust. This edition published December 2024. Review due December 2027. NBT003743
