Lupus Site - a guide for lupus patients and their families

Is a recording of the electrical activity in muscle.
It usually takes 30 to 60 minutes to perform, depending on the number of muscles to be tested.

An EMG is used to detect disorders that mainly affect the muscles.
It is also used to diagnose muscle problems caused by other diseases, such as nerve dysfunction.
An EMG can show the difference between true weakness and the reduced use of a muscle due to pain or lack of motivation.
Peripheral nerve damage, known as peripheral neuropathy, can also be detected on an EMG.  

Electrical activity is measured during muscle contraction & when they are at rest.  
A needle electrode is placed into a skeletal muscle.
Skeletal muscles are attached to bones, and are the muscles that control posture and movement.
The electrical activity of the muscle is displayed on an oscilloscope as an electrical waveform.
An amplifier can be used so that the sound of the electrical activity can also be heard.

During the test, the person may be asked to contract the muscle slowly.
The test takes about 30 to 60 minutes.
There may be some discomfort when the needle electrode is inserted.