Electrodiagnostic Medicine

Electrodiagnostic Medicine

Electrodiagnostic medicine is a medical subspecialty. Specially trained physicians use information from a patient’s history and physical exam, along with the results from tests they conduct to record and analyze electrical impulses between muscles and nerves, to diagnose, evaluate and treat neuromuscular, musculoskeletal, and nervous system disorders. Here are some frequently asked questions (FAQs) patients may have about an electrodiagnostic appointment. If you have other questions, please discuss them with your physician or locate a Board certified physician through the ABEM directory.

Neuromuscular medicine is the practice of medicine that involves the care of adult and pediatric patients with disorders of the peripheral nervous system (PNS) and its connections with the central nervous system. The PNS includes the motor and sensory neurons, peripheral nerves, neuromuscular junctions, and muscles. The care of patients with neuromuscular symptoms and signs includes physical examination, clinical investigation, diagnosis, management, and counseling for patients and their families. Neuromuscular medicine requires training and knowledge beyond that expected of a general neurologist or physiatrist. Electrodiagnostic medicine is a part of neuromuscular medicine.

Who performs the needle electromyogram (EMG) and nerve conduction study?

The AANEM’s policy is that an appropriately trained doctor should do all needle EMG testing. A trained technologist under a doctor’s supervision can perform nerve conduction studies.

What kind of medical training do doctors who perform EMGs have?

Doctors who perform EMGs go to 4 years of medical school then have 4 more years of training in a residency program. Most work as neurologists or physical medicine and rehabilitation doctors. Medical training helps the doctor decide which tests to perform based on your symptoms. It teaches doctors what can go wrong with the human body and how to tell the difference between these problems.

Why am I being sent to the EMG Lab for tests?

You are being sent to the EMG lab because you have numbness, tingling, pain, weakness, or muscle cramping. Some of the tests that the EMG doctor may use to diagnose your symptoms are nerve conduction studies and needle EMGs. The EMG doctor will examine you to decide which tests to do.

What does an NCS show?

Nerve conduction studies show how well the body’s electrical signals are traveling to a nerve. This is done by applying small electrical shocks to the nerve and recording how the nerve works. These shocks cause a quick, mild, tingling feeling. The doctor may test several nerves.

What happens during a needle EMG?

For this test, a small, thin needle is put in several muscles to see if there are any problems. A new needle is used for each patient, and it is thrown away after the test. There may be a small amount of pain when the needle is put in. The doctor tests only the muscles necessary to decide what is wrong. The doctor will look at and listen to the electrical signals that travel from the needle to the EMG machine. The doctor then uses his medical knowledge to determine what could be causing your problem.

How long will these tests take?

The tests usually take 20 to 90 minutes. You can do any of your normal activities, like eating, driving, and exercising, before the tests. There are no lasting side effects. You also can do your normal activities after the tests.

How should I prepare for the tests?

Tell the EMG doctor if you are taking aspirin, blood thinners (like Coumadin®), have a pacemaker, or have hemophilia. Take a bath or shower to remove oil from your skin. Do not use body lotion on the day of the test. If you have myasthenia gravis, ask your EMG doctor if you should take any medications before the test.

When will I know the test results?

The EMG doctor will discuss your test results with you or send them to your regular doctor. After the exam, check with the doctor who sent you to the lab for the next step in your care.

Carpal Tunnel Syndrome

What is Carpal Tunnel Syndrome?

The carpal tunnel is a small tunnel made of bones and ligaments in the wrist. The median nerve runs down the forearm through the tunnel and into the hand on the palm side of the hand and provides feeling to the hand and fingers. The median nerve can become compromised from inflammation under this tunnel, which leads to carpal tunnel syndrome. The carpal tunnel does not allow for movement or growth of the nerve. Therefore, when it inflames, the median nerve is constricted and does not allow blood to flow through the hand to the fingers.

What causes Carpal Tunnel Syndrome?

Carpal Tunnel Syndrome (CTS) can be a result of many different things. It can be due to work, lifestyle, health, injuries, and even genetic predisposition. The most common cause of CTS is repetitive motion. Certain conditions like diabetes, pregnancy, and obesity can predispose somebody to CTS. Common symptoms include numbness and pain in the hand. This is typically worse at night and can awaken one from sleep. It is typically relieved by shaking the hand. Other symptoms can be the tendency to drop things, difficulty manipulating small objects, and a burning sensation. With progression of the carpal tunnel syndrome there can be decreased sensation in the hand, muscle atrophy in the palm, and decreased hand strength and function.

How is Carpal Tunnel Syndrome diagnosed?

CTS can be diagnosed in a variety of ways. Physical examinations can show evidence of CTS. A Tinel’s test might be used by your physician. The physician will gently tap on the front of the wrist, which may cause tingling or pain in the hand. A Phalen’s test can also be used. The physician will bend your wrist fully forward and then hold it in that position for a period of time. This may produce tingling or numbness in the fingers. Physicians use nerve conduction studies (NCSs) and needle EMG to diagnose CTS. Nerve conduction studies measure electrical impulse speeds traveling through the nerve. An electrical stimulation will be sent down the nerve from various points in your upper arm and forearm. The time it takes for that electrical message to reach a point in the hand is then carefully measured by the physician. The physician will determine whether the nerves in the upper arm and forearm are carrying the message normally and whether if he message gets to the wrist and is slowed down or reduced in intensity. If a person has CTS, the speed of the impulse will decrease as it passes through the carpal tunnel. An EMG can also help diagnose CTS. Blood tests may be performed to rule out other conditions.

How is Carpal Tunnel Syndrome treated?

There can be several ways to treat CTS. Treatment can include stretching exercises, immobilizing the wrist, anti-inflammatory drugs, vitamin B6, cortisone injections, ice, modifying activities, and the extreme, surgery. Surgery for CTS is successful 95% of the time. The best way to avoid recurrence is to modify the behaviors that caused the CTS.

Ulnar Neuropathy

What is Ulnar Neuropathy?

Ulnar neuropathy is a common problem. It happens when the ulnar nerve (in the arm) becomes compressed. Many people temporarily experience this when hitting their “funny bone.” It causes numbness, tingling, and pain down the arm and into part of the hand.

Who gets Ulnar Neuropathy?

Anyone can get ulnar neuropathy. There can be several causes, including trauma, a tumor, or arthritis.

How is Ulnar Neuropathy diagnosed?

After taking the patient’s history, a physician may perform physical tests, electrodiagnostic or nerve conduction studies, and imaging tests such as MRIs.

How is Ulnar Neuropathy treated?

Splinting can be helpful in treating ulnar neuropathy. If the problem comes from an improper posture or repetitive motion, those postures and motions should be avoided. Anti-inflammatory drugs can be helpful as well. Surgery is sometimes necessary.


What is Radiculopathy?

Nerve roots exit the spine and enter the body. If one of these roots is sick or injured in the area where it leaves the spine, it is called a radiculopathy. Some disease states can cause this, but more often it is a mechanical cause like a herniated disc, bone spur, or stretching event. This can cause numbness, tingling, pain, and weakness.

Who gets Radiculopathy?

Anyone can get a radiculopathy. Sometimes it is caused by a herniated disc, and sometimes it is caused by an injury.

How is Radiculopathy diagnosed?

After taking the patient’s history, a physician may perform some physical tests, an EMG, an X-ray, or MRI.

How is Radiculopathy treated?

Treatment can include medication, physical therapy, steroid injection in the spine, and even surgery.

Tarsal Tunnel Syndrome

What is Tarsal Tunnel Syndrome?

Tarsal tunnel syndrome happens when the tibial nerve becomes entrapped. The tibial nerve runs down the back of the leg, through the ankle and into the foot. If anything pinches this nerve (swelling or trauma), tarsal tunnel syndrome can occur. It can cause pain and tingling which gets worse throughout the day.

Who gets Tarsal Tunnel Syndrome?

Anyone can get tarsal tunnel syndrome, but adults are usually the most affected. Causes can vary — arthritis, obesity, scarring after trauma, or a tumor.

How is Tarsal Tunnel Syndrome diagnosed?

After taking the patient’s history, a physician may perform an EMG or nerve conduction study. Magnetic resonance imaging (MRI) can also be used to see if anything is pressing against the tibial nerve.

How is Tarsal Tunnel Syndrome treated?

In most cases, anti-inflammatory drugs, physical therapy, or orthotic devices can help tarsal tunnel syndrome. If these treatments do not work, surgery can be useful.


What is Polyneuropathy?

Neuropathy is a general term that refers to a wide variety of problems that can affect the nerves. Common symptoms include numbness, tingling, and weakness, depending on which nerves are affected. If the problem is at one specific location along one nerve, it is called a mononeuropathy. In other cases, many nerves are affected throughout the body. When many nerves are affected, this is referred to as polyneuropathy. “Peripheral neuropathy” is a phrase that refers to problems within the nerves that are located in the peripheral nervous system (the part of the human nervous system outside of the brain and spine, such as the nerves located throughout the arms and legs). Consulting a physician who specializes in performing special tests that examine the patient’s muscles and nerves will help to obtain an accurate diagnosis.

Radial Nerve Palsy

What is Radial Nerve Palsy?

Radial nerve palsy is a result of compression of the radial nerve, often caused by fracture of the humerus bone. This results in pain, weakness, or loss of function in a person’s wrist, hand, and fingers.

Who gets Radial Nerve Palsy?

Anyone can get radial nerve palsy, especially if the radial nerve is injured.

How is Radial Nerve Palsy diagnosed?

After taking the patient’s history, a physician may perform an EMG and a nerve conduction study. X-rays or an MRI may also be used to detect injury to the humerus.

How is Radial Nerve Palsy treated?

Treatment usually depends on the reason for the radial nerve palsy. If the palsy is caused by swelling, anti-inflammatory medication can be used to relieve pressure on the nerve. If the humerus has been injured, splinting can be used to help keep the limb stable and allow the body to heal. Depending on the level of injury, surgery may also be required.

Used with permission by AANEM

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