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What Is an EMG Test?

Electromyography (EMG) is a medical test that involves nerve conduction study of the muscles and the nerve cells that regulate them in terms of wellness. Such nerve cells are referred to as motor neurons. They relay electrical impulses that induce contraction and relaxation of muscles. These electrical signals are converted into diagrams or numbers by an EMG, helping doctors provide medical advice.

When someone is displaying signs of a muscle or nerve dysfunction, a doctor may order an EMG. Tingling, numbness, or unexplained stiffness in the muscles may be part of these effects. The findings of EMG will help the doctor identify muscle diseases, nerve damage, and disorders that influence the nerve-muscle relation.

Before an EMG Test, What Should You Know?

You may notify your doctor before the test if you are taking anticoagulation or blood-thinning medications or have a pacemaker or implanted defibrillator.

But these will generally produce no complications, and an EMG test can be carried out safely. You do not have to take antibiotics before an EMG. On the day of the test, you should take any medicines that you usually take. There is no need for specific preparation.

Why Is an EMG Test Done?

If you have signs or symptoms that may indicate a nerve or muscle disorder, your doctor might order an EMG. These symptoms may include:

  • Difficulty speaking, chewing or swallowing
  • Persistent pain in the feet, legs, arms or hands
  • Numbness, tingling or paralysis in the limbs
  • Muscle weakness or stiffness
  • Muscle wasting
  • Twitching, cramping or spasms
  • Loss of fine motor control
  • Pinched nerve

To help diagnose or rule out several conditions, EMG results are often necessary if you have:

  • Muscle disorders, such as polymyositis or muscular dystrophy
  • Diseases that affect the nerve-muscle connection, such as myasthenia gravis
  • Nervous disorders outside the spinal cord (peripheral nerve), such as carpal tunnel syndrome or neuropathy of the periphery
  • Disorders that affect motor neurons, such as amyotrophic lateral sclerosis or polio, in the brain or spinal cord
  • Disorders that affect the root of the nerve, such as a herniated spine disk

EMG Test Risks may include:

  • The risk of severe complications or side effects is lowest for electromyography tests. However, during or after an electromyography needle test, many people experience nerves and muscle pain.
  • The rest and use of over-the-counter pain relievers may help alleviate muscle pain faster; but usually, in a couple of days, this side-effect will resolve itself.
  • In sporadic cases, after a needle test, a person can experience soft tissue (lymphedema) swelling or skin infection in the vicinity of the puncture site.
  • In a nerve conduction study test, some people may feel more discomfort or pain.
  • In fact, in one study from 2014, 200 people receiving tests for electromyography and nerve conduction studies were surveyed by researchers, and 58.5 percent said the nerve conduction studies test was uncomfortable.

Procedure Application

Electromyography EMG is an outpatient procedure that can be performed in a hospital or clinic.

EMG tests are done by neurologists, and rehabilitation doctors. Neurologists specialize in the advice, diagnosis or treatment, and management of nervous system-affecting conditions as well.

A neurologist can administer an electromyography test on their own or with a specially trained technician.

How to Make Preparation When Attending an EMG or Nerve Conduction Study Medical Advice Diagnosis Test

During and after the test, a neurologist will explain how the procedure works and what to expect. A person can raise any questions they have with the neurologist at this point.

The neurologist doctor may be notified to provide medical advice if you:

  • Take any prescription or over-the-counter medications, particularly blood thinners
  • Have a disorder with bleeding
  • Have a pacemaker or cardiac defibrillator

A person should do the below to prepare for the test:

  • The night before or the morning of the test, take a shower to remove excess oil from your skin
  • A few days before the exam, stop using lotions, creams or body oils
  • Dress up in loose-fitting, comfortable clothes

Before the procedure, remove any jewelry, watches, eyewear or metal objects.

EMG Procedure Needle

An EMG needle test measures the reaction of the muscles to electric pulses.

One or more thin and sterile needles electrodes are placed in the muscle by a neurologist or assistant technician. Some people may experience some minor discomfort.

  • The needle electrodes detect and contract the electrical activity of the muscle impulses.
  • The needle electrodes send this information into an oscilloscope, which shows electric signals as waves.
  • The neurologist or technician removes the needle electrodes after the test is completed.

This test typically examines several nerve disorders and takes approximately 1 hour, but dependent on the number of nerves the neurologist wants to test, it can take longer.

Is Having an EMG or a Nerve Conduction Study Painful?

In all patients, pain is the most common EMG complication, causing some discomfort either from the nerve conduction or the needle tests. In the needle portion, most surveys find pain more frequent. The study is usually well-tolerated, but it is almost unbearable for some patients.

Before referring to EMG, it is important to discuss and understand a patient's pain because stopping mid-study due to pain sacrifices patients' resources, adds to their discomfort, and creates the challenge for the electromyography to interpret from limited data.

Patients who report higher pre-test pain and anxiety typically report more pain during the procedure. Pharmacological interventions (e.g., skin sprays or oral analgesics) and non-pharmacological interventions (e.g., calming music and/or providing pre-procedure information about the anxiety relief test) have been attempted to relieve pain during EMG.

What Is the Significance of Abnormal Electrical EMG Results?

An irregular result of EMG implies that there is a problem in a muscle electrical activity field, which could be turning on and off when it is active, how active it is, whether it is more or less active, and exhausted. In diagnosing several nerve and muscle disorders, this may provide an indicator of muscle activity.

One part of making and offering advice on diagnosis or treatment is electromyography, checking the electrical signals and electrical activity. The findings can not establish a specific diagnosis, but it may limit the possibilities.

In seeking to develop a neuromuscular diagnosis, you may feel and know second opinions are helpful. Some medical centers also give second medical advice diagnosis in the field remotely. Keep in mind that a second opinion on the examination outcome is not a negative reflection on the doctor's advice, diagnosis, or treatment. It provides additional feedback about your situation and reassurance there are no nerve disorders.

How Long Does an Electromyography Test Take?

Depending on the condition being evaluated and the study's findings, EMG testing usually takes anywhere from 30 to 90 minutes. A report will be sent to your doctor that includes the findings and an interpretation.

What the Results May Tell the Medical Health Provider

If you are present with the neurologist who ordered the electromyography test, they can immediately review the results. However, if another health care professional conducts the test, they will not see the results until a follow-up meeting with their neurologist is scheduled.

Results of electromyography testing:

  • When the muscles are healthy, an electromyography test's electrical activity should be low when the nerves and muscles relax.
  • When a nerve stimulates a muscle contraction, you may feel a burst of electrical activity or "motor unit action potential."

Both electromyography and nerve conduction studies can help doctors identify any neuromuscular symptoms and their underlying cause.


July 21, 2023

I had a knee replacement in May 2 2023 .After the operation i found out that I have a foot flop. Im going for a EMG on my foot/leg. Can they my foot with out an operation on my spine?
- Lloyd Rosensteel
Reply From: OrthoCarolina

July 26, 2023

Hi, we had question about this too so we reached out to Dr. Macknet about it! Here is what he said “Foot drop ("Foot Flop") after total knee arthroplasty is fortunately uncommon, but patients with larger deformities that need to be corrected during surgery are at a higher risk. The foot drop is due to injury or stretch to the common peroneal nerve and most patients will improve their nerve palsy (foot drop) with time. Nerve studies like an EMG are used to monitor the progress of the nerve injury recovery. There are some patients that have no recovery or an incomplete recovery. In this cohort of patients ankle braces can be used to improve quality of life, or in specific circumstances foot surgery can be offered.” It is always best…… please let us know if we can assist in finding a surgeon closest to you.