Electromyography and Nerve Conduction Velocity

  • About Electromyography and Nerve Conduction Velocity

    All of our nerves and muscles use electricity to get things done. In fact, you can think of your body as a machine with incredibly intricate wiring. To be sure, it’s more complex than any wiring system that an electrician would design. But—just as an electrician would do if some part of a machine wasn’t working as it usually does—a doctor can test how your child’s nerves and muscles are conducting electricity.

    Nerve conduction studies (NCS) and electromyography (EMG) are specific tests that help your child’s doctor see how his nerves and muscles are working. NCS measures how electrical signals travel through the nerves, and EMG records the signals moving through the muscles. Together, these tests are often called “EMG testing.”

    The nerves tested in nerve conduction studies are called “peripheral nerves.” They’re the nerves outside of the brain and spinal cord carrying messages throughout your child’s body. They allow your child to receive sensory information (like how an object feels when he touches it) and control his muscles.

    EMG testing can help your child’s doctor diagnose many different neuromuscular and muscular disorders. It’s also used to check on how your child’s nerves and muscles are functioning later on, after he’s already been diagnosed and gotten treatment.

    Here is some basic information about how the test works:

    • In nerve conduction studies (NCS), a doctor places three electrodes (stickers) on the part of your child’s body being tested, then sends small amounts of electrical current through your child’s nerves. These feel like static electricity that you experience in the winter. This part of the test usually takes 30 to 45 minutes.
    • In electromyography (EMG), a doctor places a very thin needle electrode (similar in size to the needles used in acupuncture) into one or more of your child’s muscles, and then takes recordings of the electrical activity in the muscle. This part of the test usually takes no more than 15 minutes.
    • EMG is sometimes uncomfortable, but children are usually able to tolerate it well.
    • On rare occasions, the test is done with general anesthesia.
    • Most children are able to go back to school the same day.

    How Boston Children’s Hospital approaches EMG studies

    Our EMG laboratory is just for kids. That means that all of our physicians and technologists are experienced in working with children, making them as comfortable as possible and putting them at ease during what can otherwise seem like a scary test. The lab is staffed by neurologists in our Neuromuscular Program.

    Founded it 1979, our EMG lab continues to offer the most sophisticated testing possible for our young patients. One of our special capabilities is single-fiber EMG, a specific test that’s useful for diagnosing myasthenia gravis but that’s rarely performed by pediatric specialists.

    Nerve conduction studies and electromyography (EMG studies): Reviewed by Peter Kang, MD

    © Boston Children’s Hospital, 2010

    Boston Children's Neurology and Neurosurgery ranked #1

    Boston Children’s has been ranked #1 in Neurology and Neurosurgery by U.S. News & World Report in their 2014-15 rankings of pediatric hospitals. Get all the details on the U.S. News website

     

    Searching for strength

    Several of our patients are featured in an article on rare congenital myopathies from the spring 2009 issue of Vector, a Boston Children’s publication on research.

    Boston Children's Hospital
    300 Longwood Avenue 
    Fegan 11 
    Boston MA 02115

    Tel: 617-355-8235 
    Fax: 617-730-0279


  • Electormyography (EMG) testing

    Nerve conduction studies (NCS) and electromyography (EMG) help your child’s doctor see how his nerves and muscles are working. Together, these tests are often called “EMG testing.”

    EMG testing can help your child’s medical team diagnose many different neuromuscular and muscular disorders. These tests are also used to check on how your child’s nerves and muscles are functioning later on, after he’s already been diagnosed and gotten treatment.

    EMG testing can help diagnose and evaluate a variety of disorders that affect your child’s peripheral nervous system, such as:

    Nerve conduction studies (NCS)

    The first part of the study, NCS, measures how electrical signals travel through your child’s nerves. This part usually takes about 30 to 45 minutes.

    A doctor places three electrodes (stickers) on the part of your child’s body being tested (usually his arm or leg). Then the doctor uses a stimulator to send small amounts of electrical current through your child’s nerves. This isn’t painful; it feels like static electricity that you experience in the winter when you walk across a carpet and touch a metal doorknob. The electrodes record how strongly and quickly signals travel through your child’s nerves. This measurement is called nerve conduction velocity (NCV).

    Electromyography (EMG)

    The second part of the study, electromyography (EMG), records the signals that are moving through your child’s muscles. The information from the test is called an electromyogram. An EMG usually takes no more than 15 minutes.

    A doctor places a very thin needle electrode (similar in size to the needles used in acupuncture) into one or more of your child’s muscles. When this happens, your child will feel a tiny pinch. Then the doctor takes recordings while the muscle is at rest and, if possible, while your child moves the muscle. Your child will not receive any electrical stimulus through the needle; it’s just a measuring device.

    This part of the study is sometimes uncomfortable, so our doctors always try to balance the need for information with the comfort of your child. If your child becomes really uncomfortable, your doctor may decide to stop the study early.

    We often describe the EMG needle as a “microphone,” because we actually listen to the sound of the electrical signal through speakers. Many children become intrigued by the crackling noise. In fact, children often offer their ideas about what their muscles sound like—such as rain on a roof, a lobster boat or a motorcycle. Most children tolerate the study without too much trouble, especially with their parents in the lab with them.

    Specialized testing

    In some cases, we perform specialized forms of EMG testing in order to answer specific questions your child’s doctor may have. These specialized tests may make the study take slightly longer than the usual timeframe of one hour.

    One specialized test we perform is single-fiber EMG, a test that can help diagnose a condition called myasthenia gravis.

    If your child needs an extended version of these tests, we may perform her EMG in our Day Surgery Unit using general anesthesia.

    Q: Is EMG testing painful?

    A:The stimuli in nerve conduction studies (NCS) feel like static electricity (like when you walk across a carpet and touch a metal doorknob). The electromyography (EMG) portion of the test may be a bit painful for some children. But many children become distracted by the crackling sound of their muscles’ electrical activity and are able to tolerate the study without too much difficulty.

    Q: What kind of information does the study give?

    A:These tests help your child’s doctor see how his nerves and muscles are working. NCS measures how electrical signals travel through the nerves, and EMG records the signals moving through the muscles. This information can help your child’s doctor diagnose many different neuromuscular and muscular disorders.

    Q: Can my child be sedated?

    A:In most cases, we can perform this test more quickly and get better information if your child is not sedated or under anesthesia. Fortunately, most children tolerate the study well. All of our doctors and technologists work hard to help your child understand the test and comfort him. Having you there with him helps a lot, too.

    Occasionally, when we feel we’ll get better information using general anesthesia, we may schedule your child’s EMG testing in our Day Surgery Unit. On rare occasions in which a child comes to the EMG laboratory but can’t tolerate the study (such as for some very young children), we may reschedule it in the Day Surgery Unit so it can be done under general anesthesia. General anesthesia is associated with a small risk of complications, which is why we don’t use it on a routine basis for this study.

    Q: Will my child miss school as a result of this study?

    A:The test usually only takes an hour, and most children return to school the same day. Some parents prefer to keep their child home for the rest of the day, depending on factors such as the child’s age. All children should be ready to return to school by the next day.

    Q: Does the test cause any nerve damage?

    A: No, the electrical stimuli of NCS do not cause nerve damage. The needle electrodes used for EMG are not placed near any major nerves.

    Q: Can any other tests substitute for EMG?

    A: If your doctor thinks that your child may have a muscle disorder, genetic testing may be enough to make the diagnosis. However, when the diagnosis is unclear, an EMG can help determine whether the nerves or muscles aren’t functioning normally. In some cases, a muscle biopsy or other test may be needed to provide a full diagnosis.

    Questions to ask your doctor

    If your child is going to be having EMG testing, you and your child probably have a lot of questions on your mind. What do the tests involve? Are the electrodes going to hurt my child? In these pages we’ve tried to provide some answers to questions you may have, and you should feel free to ask your child’s doctor about the tests, too.

    At a medical appointment, it can be easy to forget the questions you wanted to ask. It’s often helpful to jot them down ahead of time so that you can get the information you need and feel comfortable with the plan for your child’s testing. If your child is old enough, you may want to suggest that he write down what he wants to ask his doctor, too.

    Some of the questions you may want to ask include:

    • What will happen during the EMG testing?
    • Is there anything we need to do to get ready?
    • Will my child be able to go to back to school that day?
    • How is this test going to help in diagnosing my child’s condition?

    Coming to Boston Children's Hospital

    Visit the Boston Children’s For Patients and Families site to read all about:

    • getting to Boston Children’s
    • accommodations
    • navigating the hospital experience
    • resources that are available for your family

  • About the EMG Laboratory

    Our EMG laboratory at Boston Children’s Hospital is just for kids. That means that all of our physicians and technologists are experienced in working with children, making them as comfortable as possible during what can otherwise seem like a scary test. Our lab is staffed by neurologists in our Neuromuscular Program.

    Founded it 1979, our EMG lab continues to offer the most sophisticated testing possible for our young patients. One of our special capabilities is single-fiber EMG, a specific test that’s useful for diagnosing myasthenia gravis but that’s rarely performed by pediatric specialists.

    Zebrafish Muscles do some Heavy Lifting

    A feature on the Boston Children's Genetics website explores how tiny freshwater fish are helping researchers develop new therapies for neuromuscular diseases.

Request an Appointment

If this is a medical emergency, please dial 9-1-1. This form should not be used in an emergency.

Patient Information
Date of Birth:
Contact Information
Appointment Details
Send RequestIf you do not see the specialty you are looking for, please call us at: 617-355-6000.International visitors should call International Health Services at +1-617-355-5209.
Please complete all required fields

This department is currently not accepting appointment requests online. Please call us at: 617-355-6000. International +1-617-355-6000.

This department is currently not accepting appointment requests online. Please call us at: 617-355-6000. International +1-617-355-6000.

Thank you.

Your request has been successfully submitted

You will be contacted within 1 business day.

If you have questions or would like more information, please call:

617-355-6000 +1-617-355-6000
close
Find a Doctor
Search by Clinician's Last Name or Specialty:
Select by Location:
Search by First Letter of Clinician's Last Name: *ABCDEFGHIJKLMNOPQRSTUVWXYZ
More optionsSearch
Condition & Treatments
Search for a Condition or Treatment:
Show Items Starting With: *ABCDEFGHIJKLMNOPQRSTUVWXYZ
View allSearch
Locations
The future of pediatrics will be forged by thinking differently, breaking paradigms and joining together in a shared vision of tackling the toughest challenges before us.”
- Sandra L. Fenwick, President and CEO
Close