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Electromyogram (EMG) Test: What to Expect Before, During, and After
If your doctor referred you for electromyography (EMG), the good news is the procedure is fairly quick and straightforward. It is a useful tool for diagnosing conditions related to the muscles and the motor neurons.
At Interventional Spine & Surgery Group, we provide fast, patient-centered care, including diagnostic procedures, near you in central and northern New Jersey, delivered by a multidisciplinary team of orthopedic surgeons, neurosurgeons, physical therapists, and other specialists. Learn more about the electromyogram procedure, how it works, what you can expect during the process, and what your results mean.
Key Takeaways
- Electromyography (EMG) is a diagnostic test that measures the electrical activity of the muscles and the motor neurons (nerves) that control them, helping to diagnose neuromuscular conditions.
- An EMG test consists of two parts: a nerve conduction study that measures how fast signals move through the nerves and a needle exam that measures the electrical signals inside a muscle.
- Preparing for an EMG test involves bathing on the day of the test, not applying lotions, creams, or oils, and wearing loose-fitting clothing.
- An EMG test takes 30 to 90 minutes and isn’t painful, although patients may experience a tingling sensation during the nerve conduction study and a slight pinch during the needle exam.
- A normal EMG result shows muscles that stay quiet at rest and have smooth, expected electrical patterns during movement, while an abnormal result shows that the electrical activity in your muscles or nerves is not working correctly.
- Interventional Spine & Surgery Group provides diagnostic procedures like electromyography tests near you in central and northern New Jersey.
What Is Electromyography?
Electromyography (EMG) is a diagnostic test that measures the electrical activity of the muscles and the motor neurons (nerves) that control them. It is used to help determine the cause of symptoms like muscle weakness, numbness, pain, and tingling. An electromyogram contains the results that the electromyography produces, which can be in the form of graphs, charts, or wave data.
An EMG test typically takes 30 to 90 minutes, and it consists of two parts: a nerve conduction study and a needle exam. The nerve conduction study involves placing small patches onto the skin that send quick electrical pulses to see how fast signals move through the nerves. The needle exam involves placing a thin needle into the muscle to track electrical signals when the muscle is resting and when it’s moving.
These electrical signals are then translated into visible waves on a monitor and audible sounds through a speaker, helping doctors determine whether symptoms are due to nerve damage, muscle disease, or an interruption in signal transmission.
What Conditions Can Be Diagnosed with EMG?
Since an EMG test measures the electrical activity of the muscles and nerves, it can help diagnose conditions related to the neuromuscular system. Conditions that are commonly diagnosed with an EMG include:
- Radiculopathy (pinched nerve)
- Nerve root compression and entrapment, such as carpal tunnel syndrome and sciatica
- Peripheral neuropathy
- Muscular disorders, such as muscular dystrophies and myopathies
- Neuromuscular diseases like amyotrophic lateral sclerosis (ALS)
- Neuromuscular junction disorders, such as myasthenia gravis
Along with an EMG test, blood tests, imaging scans, and biopsies may be used to confirm these diagnoses.
EMG vs. Nerve Conduction Study (NCS)
An EMG and a nerve conduction study (NCS) are two tests that are used together to diagnose neuromuscular issues in a process called an electrodiagnostic study. Technically, an NCS is part of an EMG, although it can also be performed separately. The EMG measures the electrical activity inside a muscle with a thin needle, while an NCS measures the speed and strength of the electrical signals in a nerve with electrodes.
| Test Type | EMG | NCS |
|---|---|---|
| What It Measures | The electrical activity inside a muscle | Speed and strength of electrical signals traveling through a nerve |
| How It’s Done | Inserting a thin, sterile needle into specific muscles | Patch electrodes taped to the skin over a nerve |
| What It Detects |
|
|
Preparing for an EMG
When you haven’t had an EMG test done before, it’s normal to be nervous or unsure about what will happen. However, knowing what to expect can help put your mind at ease. Before the test, your doctor will give you some instructions to properly prepare. They typically include things like:
- Bathe on the day of the test to clean your skin so the electrodes can attach
- Avoid putting on lotions, creams, or oils that can block electrical signals or prevent the electrodes from sticking
- Wear loose clothing so the doctor and technician can reach the necessary areas
- Bring your medication list with you
If you take blood-thinning medications or have a pacemaker, ask your doctor for any special instructions before the test day arrives. You won’t need to fast or have someone drive you home after. Since an EMG is an outpatient procedure, you can go home the same day.
What Happens During the EMG?
An EMG test typically takes 30 to 90 minutes. The first part of the test is the nerve conduction study. The technician will put electrode patches on your skin over specific nerves, typically the median nerve, ulnar nerve, or sural nerve. Once the electrodes are placed, mild electrical pulses are sent through them to see how fast the nerves are working. You may feel a quick zap or tingling feeling, but it’s not painful.
The next part is the needle EMG exam, where the doctor will insert a very thin needle into certain skeletal muscles. Which muscles the needle is inserted into will depend on the symptoms, but they often include muscles in the hands and arms; feet and legs; or neck and spine. After the needle is in place, you will be told to relax and then gently flex or move the muscle. A machine will show wave data and make popping/clicking sounds so the doctor can see and hear your muscle activity. This part is not painful, but you can feel a quick pinch or mild ache when the needle is inserted.
An EMG test doesn’t have a long recovery time, so you can go home afterward and resume your normal activities. You may experience mild soreness or a bruise where the needle was inserted, but there shouldn’t be any long-term side effects. You will receive your results within a few days after the specialist reviews the data and sends the report to your doctor.
Understanding Your EMG Test Results
When you receive your EMG test results, you may be confused about what they mean. Some key terms you may see in your report include amplitude, which measures the signal height, conduction velocity, which measures the signal speed, and latency, which measures how long it takes for a signal to reach the muscle.
A normal result will show that the muscles stay quiet at rest and show smooth, expected electrical patterns during movement. This helps rule out a muscle disease or major nerve injury. An abnormal result can show either resting activity, which means electrical signals are activated when you’re not moving, or contraction activity, which shows abnormal wave shapes or poor recruitment patterns when you flex the muscle. Resting activity can suggest a pinched, damaged, or inflamed nerve, while contraction activity can indicate nerve or muscle disorders.
If your EMG results are abnormal, your doctor will correlate the findings with your symptoms to help pinpoint their exact cause. They may also order additional tests or imaging scans, or they may provide a referral to a specialist like a neurologist or physiatrist.
Get an Electromyogram Near You in New Jersey
If you’re dealing with muscle weakness, numbness, and tingling and are trying to pinpoint the cause, electromyography can help. This minimally invasive diagnostic procedure can be used to help diagnose a range of neuromuscular issues, helping you and your doctor find the cause of your symptoms and determine the best treatment method.
You can access electromyograms and other diagnostic procedures at Interventional Spine & Surgery Group, where we prioritize fast scheduling and patient-centered care. Here, we can see you now, we care, and we’ll help you get better. Contact us today to learn more about electromyography or to schedule an appointment near you in central or northern New Jersey.
Frequently Asked Questions About Electromyography
What is an EMG test used for?
Electromyography (EMG) test is a diagnostic study that gauges the electrical activity of the muscles and the motor neurons (nerves) that control them. It helps verify the cause of symptoms like muscle weakness, numbness, and tingling and diagnose neuromuscular disorders.
Is an EMG test painful?
No, an EMG test is not painful. You should only feel a mild tingling or zap during the nerve conduction study and a quick pinch when the needle is inserted for the needle test.
How do I prepare for an EMG?
To prepare for an EMG, you should bathe on the day of the test; avoid applying lotions, creams, or oils; and wear loose-fitting clothing. You do not need to fast or stop taking medications (unless you’re on a blood thinner, in which case you should ask your doctor).
How long does an EMG take?
An EMG takes anywhere from 30 to 90 minutes, and you can return home afterward and resume your normal activities.
What is the difference between an EMG and a nerve conduction study?
Both an EMG and a nerve conduction study (NCS) are used to diagnose neuromuscular issues. However, an EMG measures the electrical activity inside a muscle, while an NCS measures the speed and strength of the electrical signals in a nerve.
What conditions can an EMG diagnose?
An EMG can help diagnose a range of neuromuscular conditions, including:
- Muscular disorders like muscular dystrophies and myopathies
- Neuromuscular diseases, such as amyotrophic lateral sclerosis (ALS)
- Neuromuscular junction disorders, such as myasthenia gravis
- Radiculopathy (pinched nerve)
- Nerve root compression and entrapment, such as carpal tunnel syndrome
- Peripheral neuropathy
Can I drive after an EMG?
Yes, you can safely drive after an EMG because you don’t receive any sedation that would impact your driving ability.
Can you get an EMG if you have a pacemaker?
Yes, you can get an EMG test if you have a pacemaker. However, it’s essential to tell your medical team about the device to ensure they take proper safety precautions.
What does an abnormal EMG result mean?
An abnormal EMG result means the electrical activity in your muscles, or the nerves that control them, is not working properly. This suggests a muscle disease, nerve injury, or nerve compression.
