EMG Testing

What is EMG testing?

Electromyography (EMG) and other electrodiagnostic tests read the electrical signals that travel from the brain to motor nerves to muscles. An injury or disease can interrupt these electrical signals, causing problems such as carpal tunnel syndrome, sciatica or nerve entrapment. Patients who experience weakness, atrophy, fatigue, cramps, muscle movements, stiffness, pain, paresthesias (tingling skin sensations), and numbness may be asked to undergo an electrodiagnostic test.

Electrodiagnostic indicators

• Entrapment neuropathies including Tunnel syndrome or nerve palsy
• Radiculopathy
• Brachial and lumbosacral plexopathy
• Peripheral nerve injuries
• Pain, numbness or weakness of upper or lower extremities
• Polyneuropathy
• Diseases of the neuromuscular junction like myasthenia gravis
• Myopathy
• Motor neuron disease
• Autonomic neuropathy

What will happen?

You may be asked to change into a gown.

A neurologist or technician will place surface or needle electrodes at various locations on your body.

Nerve conduction studies involve surface electrodes that are taped to the skin near the affected nerve, which are then stimulated with a slight electrical current. You may feel the current as a twinge or small spasm. This may cause discomfort or pain, but it should end shortly after the electrode is removed. The electrodes measure how fast the electrical signal travels. Healthy nerves can conduct signals at more than 100 miles an hour. Damaged nerves conduct signals much slower than that.

If needle electrodes are used you may feel a small pinprick as the needle is inserted, but nothing will be injected. The needles act like microphones and allow your physician to gather information about what your muscles are doing when working and at rest. You will probably be asked to contract and rest specific muscles throughout the test.

You might experience minimal bruising where the electrodes enter the skin.

What should you do before the test?

It is a good idea to take a bath or shower before the test. Do not apply lotions or creams since these may interfere with the adhesion of the electrodes.

You can take your normal medications, but remember to notify your physician if you are taking any blood thinners or have a pacemaker or implanted defibrillator.