This page explains about an electromyography and what to expect when your child comes to Great Ormond Street Hospital (GOSH) to have this procedure.
What is an electromyography?
Electromyography, or EMG, is used to test the electrical activity of nerves and muscles. It is used to diagnose conditions that may be affecting them and causing weakness.
Why does my child need this procedure?
The most common reason for this test is because your child is experiencing muscle weakness.
We have hundreds of muscles in every region of our body. Our brain controls the movement of our muscles by sending an electrical signal down a series of nerve cells, which then order our muscles to contract. In some medical conditions, the electrical activity of the muscles or nerves is not working normally, which can lead to muscle weakness.
There are many different causes of weakness. An EMG test is used to look at whether the weakness is being caused by problems with the muscles or nerve supply to those muscles.
Sometimes the EMG test will find nothing. But this is important because it indicates that other areas of your child’s body might need to be investigated, like their brain.
Even if the EMG test is abnormal, this does not necessarily mean that your child has a serious condition. There are many reasons why an EMG test can be abnormal and some of these causes are very mild, so may have little effect on your child’s development.
What happens before an EMG test?
There are no special precautions for this test. Your doctor will explain everything to you in full detail on the day of the test, and you will have the opportunity to ask them any questions.
What does an EMG test involve?
An EMG test involves the use of small electrical currents to stimulate the nerves, and the use of tiny wires that are placed into the muscle to record muscle activity.
You will stay with your child throughout the test. If your child is small enough, they can sit on your lap. If they are bigger, they will be asked to lie on a bed and you will be able to sit next to them.
The test begins by measuring the ability of your child’s nerve to conduct electrical signals. Several flat disc-shaped electrodes will be attached to your child’s skin with tape. Quick electrical pulses (lasting less than a split-second) are then administered to the nerve and the time it takes the muscle to contract in response is recorded.
Usually this causes no distress and with distraction therapy, the majority of children will pass through this part of the test with no problems.
The second part of the test looks at muscle activity.
Often, only one muscle is selected. A fine wire is inserted into your child’s muscle and they will be asked to move around, so that the electrical activity can be recorded while their muscles are contracted and at rest. The muscle activity is measured through feedback from a microphone, so you and your child will be able to hear and see the activity on a small screen.
The wire is placed into the muscle without your child seeing, and most children watch the screen and feedback from the microphone, so can find the whole experience interesting rather than frightening.
Some children, particularly at a certain age, can become upset if they are tired or being handled by someone that is not their parent. Parents will always recognise the difference between when their child is being hurt, and when their child is just upset and wishing to be somewhere else.
The team at Great Ormond Street Hospital is exceptionally experienced and can often complete the EMG test in 15 minutes. You will be able to stay with your child throughout the procedure and there will often be a visiting doctor in the clinic, who will help you with distracting your child.
Are there any risks involved?
There are no significant risks to this test. An EMG is very safe and there is very little risk of getting an infection because the wires used are sterile and disposable.
Also, the voltage of electrical pulses is very low and not high enough to cause any injury.
Will it hurt?
Your child may feel a small amount of discomfort because of the wire insertion, but the wires are very small and the team will use distraction therapy to help your child cope.
With the nerve conduction study, your child may experience mild tingling and discomfort, which may feel a little unpleasant. Keep in mind that each electrical pulse is very quick and will last less than a split-second.
After the EMG test
Your child will be sent home following the procedure. They may experience slight minor aches and pains from the testing, but there shouldn’t be any restriction of activities.
The results of the EMG test will not be discussed with you on the day. Instead, they will be sent to your consultant who will review the results along with any other investigations that your child is having done. Your consultant will then arrange to discuss these with you in person.
Last reviewed by Great Ormond Street Hospital: July 2012
This information does not constitute health or medical advice and will not necessarily reflect treatment at other hospitals. If you have any questions, please ask your doctor. No liability can be taken as a result of using this information.