EMG Testing
What is EMG Testing?
An electromyogram (EMG) is a test that is used to record the electrical activity of muscles. When muscles are active, they produce an electrical current. EMG Testing is used to detect abnormal electrical activity of muscle that can occur in many diseases and conditions, including Sciatiaca, Pinched Nerve, Spinal Stenosis, Herniated Discs, Inflammed Muscles, Injured nerves in the arms and legs etc.,.
Why is an EMG test done?
An EMG Test is often performed when patients suffer from Sciatica pain, radicular pain, tingling, numbness and muscle weakness. The EMG Test also helps to distinguish between muscle conditions in which the problem begins in the muscle and muscle weakness due to nerve disorders. The EMG Test can also be used to detect true weakness, as opposed to weakness from reduced use because of pain or lack of motivation. EMGs can also be used to isolate the level of nerve irritation or injury.
How is the EMG Test done?
The test has two parts.
Part I – Nerve Conduction Testing:
A nerve conduction velocity (NCV) test is often done at the same time as an EMG. In this test, the nerve is electrically stimulated with a stimulator device while an electrode detects the electrical impulse 'down-stream' from the site of stimulation. This is usually by taping surface electrodes (similar to those used for an EKG test of the heart) that are placed on the skin over the nerve at various locations. The resulting electrical activity after stimulation is recorded by the other electrods. The distance between electrodes and the time it takes for electrical impulses to travel between electrodes are used to calculate the speed of impulse transmission (nerve conduction velocity). A decreased speed of transmission indicates nerve disease.
The NCV test can be used to detect true nerve disorders (such as Neuropathy) or conditions whereby muscles are affected by nerve injury (such as Carpal Tunnel Syndrome). Normal body temperature must be maintained for the NCV test, because low body temperatures slow nerve conduction.
Part II – Needle Examination:
A tiny fine needle is inserted through the skin into the muscle. The electrical activity is detected by this needle (which serves as an electrode). The activity is displayed visually on an computer screen and may also be heard audibly with a speaker. After placement of the electrode, the patient is asked to contract the muscle (for example, to bend the elbow).
The presence, size, and shape of the wave form (called the action potential) produced on the computer screen provide information about the ability of the muscle to respond to nerve stimulation.
How to prepare for an EMG test?
For adults, no special preparation is needed. Instruction includes to come with loose clothing like loose shorts and T shirt and no skin lotion should be applied to arms and legs on the day of the test.
Does an EMG test hurt?
Not really. The test can be uncomfortable at times but an experienced physician can take precautions to keep such discomfort to the minimum.
An electromyogram (EMG) is a test that is used to record the electrical activity of muscles. When muscles are active, they produce an electrical current. EMG Testing is used to detect abnormal electrical activity of muscle that can occur in many diseases and conditions, including Sciatiaca, Pinched Nerve, Spinal Stenosis, Herniated Discs, Inflammed Muscles, Injured nerves in the arms and legs etc.,.
Why is an EMG test done?
An EMG Test is often performed when patients suffer from Sciatica pain, radicular pain, tingling, numbness and muscle weakness. The EMG Test also helps to distinguish between muscle conditions in which the problem begins in the muscle and muscle weakness due to nerve disorders. The EMG Test can also be used to detect true weakness, as opposed to weakness from reduced use because of pain or lack of motivation. EMGs can also be used to isolate the level of nerve irritation or injury.
How is the EMG Test done?
The test has two parts.
Part I – Nerve Conduction Testing:
A nerve conduction velocity (NCV) test is often done at the same time as an EMG. In this test, the nerve is electrically stimulated with a stimulator device while an electrode detects the electrical impulse 'down-stream' from the site of stimulation. This is usually by taping surface electrodes (similar to those used for an EKG test of the heart) that are placed on the skin over the nerve at various locations. The resulting electrical activity after stimulation is recorded by the other electrods. The distance between electrodes and the time it takes for electrical impulses to travel between electrodes are used to calculate the speed of impulse transmission (nerve conduction velocity). A decreased speed of transmission indicates nerve disease.
The NCV test can be used to detect true nerve disorders (such as Neuropathy) or conditions whereby muscles are affected by nerve injury (such as Carpal Tunnel Syndrome). Normal body temperature must be maintained for the NCV test, because low body temperatures slow nerve conduction.
Part II – Needle Examination:
A tiny fine needle is inserted through the skin into the muscle. The electrical activity is detected by this needle (which serves as an electrode). The activity is displayed visually on an computer screen and may also be heard audibly with a speaker. After placement of the electrode, the patient is asked to contract the muscle (for example, to bend the elbow).
The presence, size, and shape of the wave form (called the action potential) produced on the computer screen provide information about the ability of the muscle to respond to nerve stimulation.
How to prepare for an EMG test?
For adults, no special preparation is needed. Instruction includes to come with loose clothing like loose shorts and T shirt and no skin lotion should be applied to arms and legs on the day of the test.
Does an EMG test hurt?
Not really. The test can be uncomfortable at times but an experienced physician can take precautions to keep such discomfort to the minimum.