EMG

What is electromyography?

Electromyography (EMG) is a diagnostic procedure that evaluates the health condition of muscles and the nerve cells that control them. These nerve cells are known as motor neurons. They transmit electrical signals that cause muscles to contract and relax. An EMG translates these signals into graphs or numbers, helping doctors to make a diagnosis.

A doctor will usually order an EMG when someone is showing symptoms of a muscle or nerve disorder. These symptoms may include tingling, numbness, or unexplained weakness in the limbs. EMG results can help the doctor diagnose muscle disorders, nerve disorders, and disorders affecting the connection between nerves and muscles.

Some doctors may refer to electromyography as an electrodiagnostic exam.

Why is electromyography performed?

Your doctor may perform an EMG if you’re experiencing symptoms that may indicate 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 affect the ability of the motor neuron to send electrical signals to the muscle, such as myasthenia gravis
• radiculopathies
• peripheral nerve disorders that affect the nerves outside the spinal cord, such as carpal tunnel syndrome
• nerve disorders, such as amyotrophic lateral sclerosis (ALS)