Electromyography (EMG) is a diagnostic test to evaluate the health status of the muscles and the nerve cells that regulate them. These nerve cells are known as motor neurons, they transmit electrical signals, which cause muscles to contract and relax. An EMG procedure translates these signals into graphs or number that aids the doctor to confirm a diagnosis.

Generally, a doctor will suggest an EMG when a person is exhibiting symptoms of a muscle or nerve disorder. Symptoms include tingling, numbness, or unexplained weakness in the limbs. EMG findings can help the doctor diagnose muscle disorders, nerve disorders and disorders affecting the connection between nerves and muscles.
Doctor doing Electromyography

Purpose Of The Procedure

The doctor may conduct an EMG if a person is experiencing symptoms that may suggest a muscle or nerve disorder. Some of the symptoms associated with muscle or nerve disorder that may necessitate an EMG test include:



Muscle weakness

Muscle pain

Muscle cramping


Involuntary Muscle Twitching

The findings of an EMP can help the doctor assess the underlying cause of these symptoms. Some of the possible causes include:

Muscular Dystrophy

Any disorders that impair the ability of the motor neuron to send electrical signals to the muscle:


Peripheral nerve disorders -carpel tunnel syndrome

Nerve disorders like amyotrophic lateral sclerosis

Also Read: Muscle Weakness: Know About the Underlying Causes And Treatment Options

How To Prepare For the Test?

It is important to inform your doctor about any prescription or over-the-counter medications that you may be taking. Also, it is vital to inform the doctor if you suffer from a bleeding disorder or have a pacemaker or implantable defibrillator. A patient may not be able to take an EMG if he or she has any of these medical problems.

A person going for the procedure should do the following:

Avoid smoking for at least 3-4 hours before the test.

Bathe well to remove any oils from the skin. Don’t apply any creams after showering.

Wear comfortable clothing that doesn’t block the area that doctor will be examining. In most cases, you may have to change into a hospital gown before the procedure.

What Happens During the Procedure?

The patient has to lie down on an examination table and the doctor may ask to move you into a different position during the procedure.

EMG test involves two components – the nerve conduction study and needle EMG.

The nerve conduction study is the initial part of the test, where small sensors called surface electrodes are placed on the skin to evaluate the ability of the motor neurons to send electrical signals.

The second part of the procedure also makes use of sensors to assess the electrical signals. The sensors are called needle electrodes and they are directly inserted into muscle tissue to monitor the muscle activity while at rest and contraction.

Usually, a nerve conduction study is done first, where the doctor will place several electrodes on the surface of the skin, particularly in the areas where the patient is experiencing symptoms. These electrodes will assess how efficiently patients motor neurons communicate within muscles. Once the procedure is complete, the electrodes are removed from the skin.

Post the nerve conduction study, the doctor will perform the needle EMG. First, the affected area is cleaned with an antiseptic solution, then the doctor uses a needle to insert electrodes into the muscle tissue. The patient may feel slight pain while the needle is being inserted.

The needle electrodes will examine the electrical activity of the muscles when contracted and when at rest and these electrodes will be removed after the test is done.

During both parts of the procedure, the electrodes will send electrical signals to the nerves, where the computer will translate these signals into graphs or numerical values that can be decoded by the doctor. The whole procedure takes about 30-60 minutes.

What Do Results Mean?

The doctor will discuss the results with the patient right after the test. The EMG finding shows any electrical activity in a resting muscle, then the patient may have

Muscle disorders

A disorder involving the nerves that connect to the muscle

Inflammation due to an injury

EMG reveals abnormal electrical activity when a muscle contracts, then a person may have herniated disc or a nerve disorder, such as ALS or carpal tunnel syndrome.

Depending on the results, the doctor will suggest any further test if required or treatment options needed.