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At Orthopaedic Institute of Ohio, our goal is to treat your aches and pains and get you back to enjoying your favorite activities. Our specialists have a variety of tools at their disposal to discover the source of your concerns, determine the best course of action and assess the progress of your treatment.

If your provider instructs you to have an electromyography test, or EMG, you may be wondering what exactly this test involves and why you need it. An EMG helps us identify nerve and muscle problems. You can learn more about this type of diagnostic testing below, or reach out to our team with questions.

What Is Electromyography?

Did you know that your body generates electrical energy? Electrical signals are the messengers that send information to and from your brain. These signals travel through your nervous system, which guides nearly everything you think, do, say or feel — even if it’s unconscious.

Sensory nerves carry information about your surroundings to your brain. Motor nerves deliver signals from your brain to your muscles that tell them to contract and relax. If an injury or disease damages these nerves, it can disrupt the movement of these electrical signals. They may slow down or stop, or they might start giving your brain inaccurate messages.

Electromyography is a diagnostic test used to measure electrical activity in a muscle during various stages of contraction and at rest. The results of the test show how well the muscle responds when the nerves are stimulated.

What Is a Nerve Conduction Study?

A nerve conduction study (NCS) usually goes hand-in-hand with an EMG. Electrode stickers are applied to the skin to measure the strength and speed of the electrical signals traveling between the brain and muscles. Believe it or not, electrical signals can travel at up to 120 miles per hour in healthy nerves. If a nerve is damaged, the signal is often slower and weaker, and the response pattern may be abnormal.

NCS results are measured against a standard nerve conduction range to help determine whether the problem lies with the way the nerves are functioning or with the muscle itself. Used together, electromyography and nerve conduction studies help medical practitioners diagnose a range of muscular or neurological conditions.

What Symptoms May Lead to an EMG Test?

The symptoms that may lead your doctor to order an EMG and NCS include:

  • Muscle weakness
  • Involuntary muscle twitching
  • Muscle cramping
  • Muscle pain
  • Tingling or frequent “pins and needles” feeling
  • Numbness
  • Tremors
  • Certain types of limb pain
  • Difficulty performing daily tasks such as buttoning clothes or walking

What Is Electromyography Used to Diagnose?

EMG results can help rule out or diagnose a number of conditions, such as:

  • Amyotrophic lateral sclerosis (ALS)
  • Carpal tunnel syndrome
  • Cervical spondylosis
  • Guillain-Barré syndrome
  • Herniated disc
  • Lambert-Eaton syndrome
  • Muscular dystrophy
  • Myasthenia gravis
  • Peripheral neuropathy
  • Polymyositis
  • Radiculopathy
  • Sciatica

How Should I Prepare for Electromyography?

Please refrain from using body oils or lotions on the day of your EMG test, and bathe or shower beforehand to ensure your skin is clean. Do not drink caffeinated beverages or smoke for a minimum of three hours prior to the test. We recommend wearing loose-fitting clothing to allow for easy access to the area that will be tested. Your test provider may require you to change into a hospital gown if that provides better access.

If you are taking any medications, have an illness, use a pacemaker or have an implanted metal device, tell the person who is conducting the test. They may provide further instruction.

How Is Electromyography Done?

During an EMG and NCS, you will lie down on an examination table or sit in a reclined chair. You may be asked to adjust your position during the procedure.

The nerve conduction study occurs first. It involves attaching small sensors called surface electrodes to the surface of your skin, usually in the area where you’re having symptoms. The electrodes evaluate how well your motor nerves communicate with your muscles. The electrodes will be removed when this portion of the test is complete.

The electromyography test comes next. In an EMG, the sensors used to evaluate electrical signals are called needle electrodes. They are directly inserted into the muscle to evaluate its activity when at rest and when contracted. The electrodes “read” the electrical signals in your muscles and turn them into a graph, sound or numerical data that your provider can interpret.

The full procedure typically takes between 30 and 60 minutes.

What Can I Expect After Electromyography?

Though parts of the EMG can be uncomfortable, there is no need to take time off work or your usual daily activities, and the test will not affect your ability to drive. Some patients report soreness, bruising or a tingling sensation in the treated area following the exam. This should disappear in a few days. If you do notice increasing swelling, pain or tenderness at any of the needle insertion sites, please contact our office.

What Risks Are Associated With Electromyography?

In general, EMG is a low-risk procedure. There is a small risk of infection, bleeding or nerve injury where a needle electrode is inserted. EMG may call for special precautions if you take blood-thinning medications, as the needle electrodes may cause bleeding within the muscle. Be sure to discuss your medical status and any concerns with your provider before the test.

What Information Can Be Learned From Electromyography?

The results of an EMG are usually available within 24-48 hours after the test.

In normal muscle tissue, no electrical activity occurs while the muscle is relaxed. But if a muscle is damaged or isn’t receiving proper input from nerves, it may have abnormal electrical activity while at rest. When it contracts, the electrical activity may make unusual patterns.

Abnormal electrical activity may mean you have a muscle disorder, a connective nerve disorder or inflammation caused by an injury. Your provider will use the results of your EMG together with other factors to make a diagnosis and recommend a course of treatment.

As a leading provider of orthopedic care, Orthopaedic Institute of Ohio is committed to offering our patients access to the latest treatments and advanced techniques, including electromyography and nerve conduction studies. For more information about our diagnostic services, contact the Orthopaedic Institute of Ohio at 419-222-6622. Our team would be happy to answer your questions or schedule your exam.