What is an EMG (electromyography)?

Electromyography (EMG) is a technique that assesses the performance of muscles and their innervating nerve cells, which can be referred to as motor neurons. These nerve cells are responsible for sending electrical impulses that facilitate muscle contraction and relaxation. EMG records these impulses and presents them in graphs and figures, which assists the physician in diagnosis.

A physician would mostly request an EMG test if a patient was suffering from any muscular or nervous system diseases. Such symptoms would range from tingling and numbness to unusual weakness of the limbs and extremities. The results of the EMG help the physician determine the presence of muscle diseases, problems with the nerves, and diseases of the muscle-neuronal junction.

In some cases, electromyography is described as an electrodiagnostic examination by some physicians.

Why is EMG done?

Your doctor may perform an EMG if you re experiencing symptoms indicating a muscle or nerve disorder. Some symptoms that may call for an EMG include:

• Tingling
• Numbness
• Muscle weakness
• Muscle pain or cramping
• Paralysis
• Involuntary muscle twitching (or tics)

The results of an EMG can help your doctor determine the underlying cause of these symptoms. Possible causes could include:

• Muscle disorders, such as muscular dystrophy
• Disorders that impair the function of the motor neuron to conduct electrical impulses to

the Muscle, such as myasthenia gravis

• Radiculopathies
• Peripheral nerve conditions, involving nerves outside the spinal cord, such as carpal tunnel syndrome
• Disorders of the nerves for example, ALS

How does an EMG test work?

To appreciate how an EMG test is performed, it is necessary to understand a few things about the workings of the bodily muscles.

In the simplest of terms, the muscles in your body are connected to your motor nerves (also referred to as motor neurons) that potentialize the muscles on how to act. (Such command originates in the brain, goes down via the spinal cord and motor nerves, and finally reaches the muscles.) This stimulation leads to the inner muscle activity that causes it to bulge (contraction). Furthermore, muscle contractions will generate their electrical activity.

At rest, a muscle does not generate electrical activity. When the muscle is contracted, minimal effort is employed, leading to slight electrical activity that rises as the muscle is contracted more forcefully.

Electromyography is when a healthcare professional places a super-thin needle, which contains an electrode, inside one of your muscles to gather its activity. Electrical stimulation is not ever given via the needle. Instead, you could compare the needle to a microphone; it does not give sound out; it simply records audio input.

For example, the needle electrode can collect electric activity while the individual is either at rest or contracting the muscle. This needle is connected to the machine via a wire, allowing the provider to visualize the muscle activity at rest and during motion. It is represented in the form of waves on the monitor. They may also have an audio amplifier in which they will listen to the electrical activity pulses.

The provider then interprets these recordings to find any abnormalities. For instance, with certain muscle damages, the patient may exhibit different at rest electrical activity of the muscle. When the muscle is made to contract, abnormal activity can be measured as abnormal waves.

How to prepare for an EMG test?

Be sure to let your doctor know about all other drugs you may be taking, over-the-counter or prescription. The doctor should also be aware of any bleeding disorder, pacemaker, or implantable defibrillator you may have. You may have to be excluded from the test based on any of these conditions or devices.

If you are eligible for an EMG, here is what you should prepare before undergoing the test:

Smoking avoidance: Avoid smoking for at least three hours before surgery.

Bathe or take a shower to remove the oils from the skin surface. Do not apply lotions or creams after washing.

Wear loose-fitting, comfortable clothing that does not cover the area your doctor will be examining. You may need to change into a hospital gown during your procedure.

What is going on during an EMG test?

EPT can also be conducted at a place away from the hospital or as part of the stay in the hospital. The exact procedures may differ with each non surgical and the practices of their respective doctors. The NCS is done by a neurologist (who is a physician specialized in diseases of the brain and nerves) although some parts of the test may be done by a qualified technician.

Generally, a routine NCS procedure usually follows these steps:

• You may be asked to remove any clothing, jewelry, hairpins, eyeglasses, hearing aids or other metallic objects that might interfere with the test. If you are asked to remove clothing, you will be given a gown to use.
• You will likely sit or lie down for the test.
• A neurologist or a technologist will locate the nerve(s) to be tested.
• A recording electrode will be applied to the skin over the nerve with special paste, and a stimulating electrode placed at a known distance away from the recording electrode
• A mild, brief electrical shock through the stimulating electrode will stimulate the nerve.
• You may feel a mild discomfort for a few seconds.
• This experiment will measure and monitor using an oscilloscope the stimulation of the nerve and its detected response. An oscilloscope is an observation tool that records electrical activity in the form of waves.

How long does the EMG test take?

The test typically ranges between 60 and 90 minutes. This will depend on the number of muscles your healthcare provider needs to test.

What are expected after the EMG test?

A few days after the test, you may feel some aching or tenderness in your muscles. The discomfort from the muscle soreness is not often debilitating and will improve in less than one week. Bruising may have occurred at the skin sites where needles were inserted.

What are the risks of an EMG?

EMG is regarded as a safe procedure. As a result, complications are uncommon. Some individuals (usually those on anticoagulants) may experience post-procedural bleeding.

What do the results of an EMG test mean?

EMG tests are useful but do not typically offer a diagnosis by themselves. Your healthcare team providers will interpret the findings along with other medical tests in order to arrive at a diagnosis.

How long does it take to get the results of an EMG?

Results of the tests can be expected usually within 24 to 48 hours of completion of the testing.

When should I call my health care provider about my EMG?

Call your healthcare provider if you have:

• Heavy bleeding that does not stop.
• Severe pain or tenderness at the sites where the needles entered your skin.
• Redness, warmth, swelling, or a fever. These can be symptoms of an infection.

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