What is an EMG?
An electromyogram (EMG) is a neurodiagnostic test that measures the electrical activity of your muscles at rest and during contraction. If you have a nerve or muscle disorder, your muscles may react in abnormal ways that an EMG can measure. EMGs are often performed with nerve conduction studies to provide a more complete picture of a condition.
Why is an EMG performed?
An EMG is performed to assess nerve and muscle function or to determine the cause of muscle weakness, paralysis, or twitching. By performing an EMG, a doctor may be able to detect and diagnose conditions such as a herniated disc or amyotrophic lateral sclerosis (ALS).
What to expect:
You will be instructed about what to wear to your appointment, what to eat before the test, how the test will be performed, and how the test will feel.
Before an EMG, you may need to stop taking certain medications that impact your nervous system and you may need to stop taking blood thinners.
When you arrive for your EMG, you will lie on a bed or a table or you will sit in a reclining chair. A needle electrode will be inserted into the specific muscle being tested. You may feel a quick, sharp pain when the needle electrode is inserted into your muscle. The needle electrode is attached by wires to a recording computer. While your muscle is at rest, the muscle’s electrical activity is recorded.
You will be then asked to tighten (contract) that muscle slowly and steadily while the computer records the muscle’s electrical activity. The needle electrode may be moved a number of times to record the electrical activity in different areas of the muscle or in different muscles.
An EMG usually takes 30 – 60 minutes to complete. When testing is over, the needle electrode will be removed. You may experience some minor bruising or swelling at the needle electrode insertion sites. A full report of your EMG results may take 2 – 3 days.