EMG is a mixture of straightforward and safe tests of nerve and muscle function. The results may provide some clues to the cause of your symptoms – but they are often one part of a jigsaw, and the results of other tests may be needed in order to reach a diagnosis.
The nature of the examination varies from patient to patient. Therefore it is difficult to predict what will need to be done and how long it will take. Generally, it takes between 30 and 60 minutes, but can be longer.
The test is carried out by a medically qualified doctor, sometimes assisted by a registered technician. The doctor will need to discuss relevant symptoms with you. In order to interpret the test properly, a brief examination is likely to be needed.
Even if your symptoms are in one limb, a comparison of the findings on right and left is often useful. Depending on the initial results, it is sometimes necessary to examine both upper and lower limbs.
The test begins with:
Nerve conduction studies
The responses of nerves and muscles to a small electrical stimulus are recorded and measured. This can be a strange sensation if you have not experienced the test before. There can be little discomfort, but most patients, including young children, are able to tolerate the examination.
Occasionally, but by no means always, muscle activity is looked at in more detail using –
This involves inserting a fine needle into a muscle, or group of muscles. The electrical activity produced when you move the muscles can be seen on a screen. It gives further information about the muscles and the nerves going to them.
This part of the test produces some discomfort. Muscles may continue to ache for a while after the test, but there are no long term effects. (Rarely, it is necessary to examine muscles over the chest and neck. There is a slight risk of side effects in this case. These will be discussed in more detail should the need to examine these muscles arrive.)
As with the conduction studies most people are willing and able to have the test carried out, understanding that the information may help reach a diagnosis.
Consultant clinical neurophysiologist