Benedict C. Woo, MD

Electrodiagnostic testing measures the electrical activity of nerves and muscles to help diagnose the cause of a patient’s symptoms such as numbness, tingling, weakness, pain and loss of function in a particular area of the body. 

Through electrodiagnostic testing, a physical medicine and rehabilitation (PM&R) specialist can diagnose a patient’s ailment by identifying the damaged nerves. Injuries or diseases that affect nerves and muscles can alter these electrical signals. The two most commonly used electrodiagnostic tests are electromyography (EMG) and nerve conduction studies (NCS).

The most common problems evaluated by EMGs and nerve conduction studies include but are not limited to:

• Pinched nerves in the neck or low back

• Carpal tunnel syndrome

• Nerve or muscle injuries in the upper or lower extremities, or limbs of the body

EMGs and nerve conduction studies usually take between 20 and 30 minutes and can be performed in a PM&R specialist’s office.

An EMG can help detect injuries and diseases that damage muscle tissue or nerves by recording and analyzing the electrical activity in muscles. The physician observes the electrical signals as they are broadcast on a monitor while the patient’s muscles are at rest and during contraction. 

Nerve conduction studies are usually done with an EMG to evaluate nerve function. The test involves administering electrical stimulation to nerves and measuring the response.

Electrodiagnostic medicine specialists administer the test and report the results to the physician who ordered the testing. PM&R specialists have expertise in evaluating the patient, performing and interpreting the appropriate studies for the patient’s problems, and recommending appropriate follow-up tests and treatment.