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Electromyogram (EMG) and Nerve Conduction Studies: About Your Child's Tests

What are they?

An electromyogram (EMG) measures the electrical activity of your child's muscles. Muscles are tested when they aren't in use (at rest) and when they are tightened (muscle contraction).

Nerve conduction studies (NCS) measure how well and how fast the nerves can send electrical signals.

These two tests are often done together. If they are done together, the nerve conduction studies may be done before the EMG.

Why are they done?

Your child may need an EMG to find diseases that damage the muscles or nerves. Or an EMG may be done to find out why your child can't move his or her muscles (paralysis), why the muscles feel weak, or why they twitch.

Your child may need nerve conduction studies to find damage to the nerves that lead from the brain and spinal cord to the rest of the body. (This is called the peripheral nervous system.) Or these studies may be done to find out why your child has weakness, numbness, or tingling.

How can you prepare for these tests?

  • Tell your doctors ALL the medicines and natural health products your child takes. Some medicines can affect the test results. You may need to stop giving your child some medicines before these tests.
  • Have your child wear loose-fitting clothing. He or she may be given a hospital gown to wear.
  • The electrodes for the test are attached to your child's skin. The skin needs to be clean and free of sprays, oils, creams, and lotions.

What happens during the tests?

Your child lies on a table or bed or sits in a reclining chair so his or her muscles are relaxed.

For an EMG

  • Your child may get a sedative to help relax.
  • The doctor will insert a needle electrode into a muscle. This will record the electrical activity while the muscle is at rest.
  • Your doctor will ask your child to tighten the same muscle slowly and steadily while the electrical activity is recorded.
  • Your doctor may move the electrode to a different area of the muscle or to a different muscle.

For nerve conduction studies

  • Your doctor will attach two types of electrodes to your child's skin.
    • One type is placed over a nerve. It will give the nerve an electrical pulse.
    • The other type of electrode is placed over the muscle that the nerve controls. It will record how long it takes for the muscle to react to the electrical pulse.

How does it feel?

For an EMG

Your child may feel a quick, sharp pain when the needle electrode is put into a muscle.

For nerve conduction studies

Your child will be able to feel the electrical pulses. They are small shocks and are safe.

How long do they take?

  • An EMG may take 30 to 60 minutes.
  • Nerve conduction tests may take from 15 minutes to 1 hour or more. It depends on how many nerves and muscles your doctor tests.

What happens after these tests?

  • If any of the test areas are sore:
    • Put ice or a cold pack on the area for 10 to 20 minutes at a time. Put a thin cloth between the ice and your child's skin.
    • Ask your doctor if you can give your child acetaminophen (Tylenol) or ibuprofen (Advil, Motrin) for pain. Be safe with medicines. Read and follow all instructions on the label.
    • Do not give your child two or more pain medicines at the same time unless the doctor told you to. Many pain medicines have acetaminophen, which is Tylenol. Too much acetaminophen (Tylenol) can be harmful.
  • Your child will probably be able to go home right away.
  • Your child can go back to his or her usual activities right away.

Follow-up care is a key part of your child's treatment and safety. Be sure to make and go to all appointments, and call your doctor or nurse advice line (811 in most provinces and territories) if your child is having problems. Ask your doctor when you can expect to have your child's test results.

Where can you learn more?

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