What is an EMG (electromyogram)?

An electromyogram, also called EMG and electromyography, is a test that evaluates electrical activity within your nerves and muscles. Your doctor may recommend an EMG to help diagnose muscle weakness, muscular dystrophy, and other neuromuscular abnormalities. An EMG involves inserting tiny needles into your muscles to record electrical activity. 

An EMG is only one method used to diagnose neuromuscular abnormalities. You may have less invasive testing options depending on your condition. Discuss all your diagnostic options with your doctor to understand which options are best for you.  

Other procedures that may be performed

Your doctor may perform other procedures in addition to and EMG to diagnose neuromuscular abnormalities including:

  • Evoked potentials to analyze the electrical functioning of the nervous system. This test checks the nerve pathways through the spinal cord or from the eyes and ears. Evoked potentials can help diagnose dizziness, numbness, tingling, and visual disorders.
  • Nerve conduction velocity to study how well electrical signals travel through a  nerve

Why is an EMG (electromyogram) performed?

Your doctor may recommend an EMG to diagnose muscle and nerve diseases and conditions including:

  • Amyotrophic lateral sclerosis (ALS, or Lou Gehrig’s disease), a severe neuromuscular disease that causes muscle weakness and disability
  • Carpal tunnel syndrome, compression of the median nerve in the wrist
  • Charcot-Marie-Tooth disease, a neurological disorder causing damage and weakness to nerves in the arms and legs
  • Muscle problems including weakness, tremors, muscle stiffness, tingling, pain, twitching, spasticity, and difficulty walking
  • Muscular dystrophy, an inherited disorder that causes a progressive loss of muscle tissue and muscle weakness
  • Myasthenia gravis, an autoimmune neuromuscular disorder that causes muscle weakness
  • Polymyositis, muscle inflammation that causes decreased muscle power
  • Sciatica, compression, injury or inflammation of the sciatic nerve which causes burning or shooting pain running from the buttocks down the back of the leg

Who performs an EMG (electromyogram)?

A neurologist or pediatric neurologist performs an EMG. A neurologist specializes in diagnosing and treating diseases of the brain and nervous system. A pediatric neurologist specializes in caring for infants, children and adolescents with diseases and conditions of the brain and nervous system. A technologist may assist your neurologist during the procedure.

How is an EMG (electromyogram) performed?

Your EMG will be performed in a hospital or outpatient setting. The procedure takes one to three hours and generally includes these steps:

  1. You will dress in a patient gown and remove any items that may interfere with the an electromyogram.
  2. You might take a mild sedative.
  3. You will lie or sit down.
  4. Your care team will clean the needle insertion points on your skin with an antiseptic cleanser, and then insert the needles containing electrodes into your skin. The number of needles depends on the types of muscles your doctor is studying. You may feel a pinch as each needle goes into your skin.
  5. You will relax and contract certain muscles while a special machine records the electrical activity of the muscles. 
  6. You may hear sounds when you contract your muscles if your doctor is using an audio device during your electromyogram.
  7. Your care team will remove the needles and may apply warm compresses and give you pain medication.
  8. The neurologist will evaluate your EMG test results. The neurologist will send a report to your primary doctor who will discuss the results with you.  

Will I feel pain?

Your comfort and relaxation is important to you and your care team. You may feel quick pinches during the needle placement. Tell your doctor or care team if any discomfort does not pass quickly or you are uncomfortable in any way. Pain may distort your test results, requiring a repeat test.

You may have mild soreness where the needles were inserted. Your doctor will prescribe pain medication as needed.