EMG

EMG stands for electromyography. During an EMG examination, the electrical activity of muscles and/or nerves is recorded.

Electrodes are placed on the skin or a needle is inserted into the muscle. The electrodes detect the electrical signals that a muscle produces when it contracts. The way these electrical signals are transmitted helps determine whether there is an abnormality in the muscle or nerve.

Conditions that may reduce signal transmission include nerve damage or muscle diseases. An EMG examination helps identify the cause of symptoms such as muscle weakness, tingling, numbness, or pins and needles.

What does the examination involve?

An EMG examination takes 30 to 75 minutes and involves the following steps:

• The examiner attaches several electrodes to the skin over the muscle being tested. The skin must be clean and free of oils; otherwise, the electrodes may not adhere properly, which can interfere with the transmission of electrical signals.
• These electrodes are connected to a device that delivers small, painless electrical pulses. The muscle responds to these pulses by contracting, which may cause slight movement, such as in the hand. The level of muscle activity is displayed on a computer screen.
• If the EMG examination uses needle electrodes, the needle is inserted into the muscle. Needle electrodes provide more precise measurements than adhesive electrodes but may cause some discomfort.
• The patient’s doctor will share and discuss the results at a later time.