EMG Test

What is an EMG?

An EMG (electromyogram) can be helpful in evaluating weakness, numbness, pain and symptoms such as fatigue, cramps and abnormal sensation.

EMG_BlackAndWhite

The test is “an extension of the clinical examination” and your referring doctor will have asked a question on the referral for Dr Silbert to answer by doing the test. For example, a common question is “? cts” or in other words, is there any evidence on the test for the condition known as carpal tunnel syndrome which is a common cause of numbness or pain in the hands.

On average, the test takes about 20 minutes, but may take longer if the clinical question asked by the doctor is very complex. Sometimes only the first part of the test with nerve conduction studies are needed, but for other clinical questions the needle examination or examination of other limbs may be needed.   Further analysis of the results is performed by Dr Silbert after the test, and the results are then reported in a format that your doctor can interpret and incorporate in to your clinical management.

Nerve Conduction Studies (NCS):

The measurements taken during the tests are very precise with time variables measured in milliseconds (0.001 seconds or 1 thousandth of a second) and the size of the response measured in milliVolts (1 thousandth of a volt) or microVolts (1 millionth of a volt) . To be accurate, it is necessary to warm the hand or foot to a standard temperature. If the limb is cold, then it alters the readings.

For this test,  Dr Silbert tapes small discs on the skin and applies a brief electrical stimulus to the nerve, causing a tingling sensation. The electrical response of the nerve or muscle can determine if the nerve impulse travels normally (a healthy nerve), or abnormally (an abnormal or damaged nerve).

A healthy motor nerve in the arm sends signals which travel at more than 48 metres per second! A small delay can show the doctor where the nerve has a problem.

Electromyogram (EMG):

To understand more about the nerve and muscle function, the doctor analyses the electric activity in the muscles by inserting a fine needle electrode. Any discomfort felt is only mild. The needles are sterile and are thrown away after each patient.

Dr Silbert can determine whether the muscle is working normally by seeing the electrical activity on a screen and listening over a loud-speaker. Dr Silbert will decide whether the needle examination is required based upon the questions raised by the referring doctor, and the findings on the nerve conduction study part of the test.

Preparation for the test:

You should keep the skin free of any lotions or creams on the day of examination.

If you are taking Warfarin, or any other blood thinners you should tell the doctor before the test.  The test can still be performed but Dr Silbert may modify the approach.

Results:

The results will be analysed after you leave and a report is then sent to your doctor, who will discuss the results with you.

EMG Q & A

Is the test safe in pregnancy?

Yes

Is the test safe with a pacemaker?

Yes

Are there any special preparations for children?

Children tolerate the test very well, as long as they don’t detect their parents anxieties!

Under the age of about 10 years, children do not recognise an electrical feeling and often call it a thump!

It is important not to scare the child before the test or to threaten them. Inform them what the test is for, and explain it to them in a way that they do not think you are scared about it. Dr Silbert will take the testing very slowly and explain the test as it is performed.

Does the test hurt?

Every person is different in how they experience the test. If you have any concerns then you should discuss them with the technician or  Dr Silbert prior to the test.

The first part of the test (nerve conduction studies) has an electrical feeling. We find that people who work with electricity such as electricians and electrical technicians generally find the test more unpleasant than other people because they are used to avoiding that type of stimulation as part of their every day work. The testing can however be taken slowly and almost everyone manages the test without too much discomfort.

The second part of the test involves a very fine needle. Not everyone needs that part of the test, but if you do – the needle is very fine and nothing is injected so it is not as uncomfortable as a flu needle, and there are no major after effects.