NCV (Nerve conduction velocity) and EMG (electromyogram) are tests that show the electrical activity of the nerves and muscles.

This test is often done when a child has weakness in his or her arms or legs. It helps to figure out if the weakness is due to a muscle condition or a nerve disorder. Information from the exam will help the doctor diagnose your child’s condition

  • Electrical activity is normal and necessary for muscle movement. EMG shows any change in that electrical activity of the muscles. The EMG needle test uses small needles inserted into certain muscles to record muscle activity.
  • The NCV, or nerve conduction velocity exam tests the health of the nerves outside the brain and spinal cord. Nerve conduction tests use disks on the skin to record how nerves and muscles react to mild electrical impulses.

Both the EMG needle test and nerve conduction tests are safe.

Before The Test

  • You can explain to the child how the test is done.
  • Do not give your child coffee, tea, soda or chocolate before the test. These can prevent your child from relaxing.
  • Try to keep your child awake before the test so that he or she will be sleepy. If your child is an infant, please bring milk, pacifier or a toy to calm the child. Sometimes sedation (medicine to make your child sleepy or relaxed) is used in younger or uncooperative children.
  • Please turn off all cell phones before starting the test.
  • Children should be wearing loose clothes such as loose T-shirt and shorts, as they will make the test easy.
  • Your child’s skin should be clean and free of lotions and creams.
  • The most important role of a parent and guardian during the test is to help your child stay calm and relaxed during the test.

 How the Test Is Done

  • Your child will lie on a table. Small stickers, called electrodes, are placed on your child’s legs and arms. Wires to the EMG machine connect these electrodes.

There are 2 parts to the test: the nerve conduction test and the muscle or EMG test. The NCS is usually done first.


  • The nerve conduction test is done by placing disks on the skin over certain nerves and muscles and recording how they respond to mild electrical impulses.
  • These electrical impulses feel like little “shocks.”
  • The response of the nerves is recorded, which allows to study the nerve activity.

The EMG Test

The EMG needle test records muscle activity at rest and during movement.

  • The EMG needle test uses small needles that are inserted into certain muscles to record the muscle activity.
  • It will feel like a sharp pinprick. Child may feel a mild, dull ache while the needle is in place.
  • Child might be asked to perform certain movements after the needle is inserted. For example, your child might be asked to bend his or her elbow.
  • The electrical activity of the muscles is shown on the machine and may also be heard through a microphone.


  • The length of time the test takes is different for each child. Usually the test takes between 30 and 90 minutes to complete.
  • Both the EMG needle test and nerve conduction tests are safe.

After the Test

After the test, the small needles and the disks will be removed.

  • There are no after-effects from this test.
  • Your child can return to his or her normal activities after the test.
  • Your doctor will discuss the test results with you.