EMG Testing: A Patient's Guide

What is an EMG test?

Electromyography (EMG) is a form of electrodiagnostic testing that is used to study nerve and muscle function. It is commonly performed by a physiatrist or neurologist with special training for this procedure. An EMG nerve test can provide your doctor with specific information about the extent of nerve and/or muscle injury and can also determine the exact location of injury and give some indication whether the damage is reversible.

What is an EMG test used to diagnose?

Conditions that EMG testing helps diagnose include:

  • Carpal tunnel syndrome
  • Pinched nerve
  • Radiculopathy
  • Sciatica
  • Neuropathies
  • Muscle diseases
  • Muscular dystrophy
  • ALS (Lou Gehrig’s disease)
  • Myasthenia gravis

Your doctor may order an EMG test if you experience any of the following symptoms:

  • Numbness
  • Decreased sensation
  • Tingling or frequent feeling of "pins and needles"
  • Radiating pain or burning sensation
  • Muscle spasms or weakness
  • Difficulty performing daily tasks such as walking, buttoning clothes or handling objects

How long does an EMG test take?

EMG testing usually takes anywhere from 30 to 90 minutes, depending on the condition being tested and findings of the study. A report that includes the results and an interpretation will be sent to your doctor.

Some people ask "is an EMG test painful?" There are actually two parts to EMG testing and both may result in some discomfort, but they are usually well tolerated without any need for pain medication. In most cases, your doctor will perform both elements, but in some situations, only one or the other may be done. The two elements of the EMG nerve test are:

  • Nerve conduction study – The nerves are stimulated at different points with small electric shocks, artificially activating them so their function can be measured.
  • Needle exam for muscle testing – Very fine needles are inserted into several muscles. Each needle has a microscopic electrode that picks up both the normal and abnormal electrical signals given off by a muscle.

What you should know before an EMG test?

If you are taking anticoagulation medications or blood thinners, or if you have a pacemaker or implanted defibrillator, you should notify your doctor before having the test. But in general, these will not create any complications and you can have an EMG test safely. If you have a joint replacement or other artificial implant in your body, do not need to take antibiotics prior to the EMG (as you may for dental procedures or certain types of surgeries). You should take any medications your normally take on the day of the test. No special preparation is necessary.

An EMG test is extremely safe. EMG needles are used for only one patient, are not recycled, and are immediately disposed of following use. Side effects may include some muscle soreness, which rarely lasts more than an hour or two after the exam.


Headshot of Joseph H. Feinberg, MD
Joseph H. Feinberg, MD
Medical Director, Center for Brachial Plexus and Traumatic Nerve Injury
Attending Physiatrist, Hospital for Special Surgery

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