Electromyography

Aprocedure that measures the electrical activity in muscles. Electromyography (EMG) can be used to investigate weakness or paralysis. Small disc electrodes are attached to skin over the muscle being tested, or fine needle electrodes may be inserted into the rouscle. Electrical impulses passing through the muscle are detected by the electrodes and converted into signals that are displayed on a screen and recorded. Changes in electrical wave patterns indicate certain muscle and nerve disorders.

EMG takes 30 to 60 minutes, depending on the number of muscles examined. The test has no adverse effects.

Electromyography is not a simple test, but a complex consultation. Because of the needle electrodes, electromyography may be somewhat painful or extremely painful to the patient, and the muscle may feel tender for a few days. This test may be used to diagnose peripheral nerve disorders, such as carpal tunnel syndrome. There are two types of Electromyography: the surface electromyography and the intramuscular electromyography. In both types of Electromyography, the electrical activity is displayed visually on an oscilloscope and may also be displayed audibly through a microphone.

Purpose

Electromyography can help diagnose many muscle and nerve disorders, including:

• Electromyography is most often used when people have symptoms of weakness and examination shows impaired muscle strength.
• Nerve lesions.
• Amyotrophic lateral sclerosis.
• It can also help to differentiate primary muscle conditions from muscle weakness caused by neurologic disorders.
• Mitochondrial myopathies.
• Muscular dystrophy.

How to prepare for the test?

• No special preparation is usually necessary.
• The patient may lie down or sit during the test. 
• Avoid using any creams or lotions on the day of the test.
• Make sure that your skin is clean.

Precautions

• No special precautions are needed for this test.
• Persons with a history of bleeding disorder should consult with their treating physician before the test.
• Also, persons on blood thinners should relay this information to the physician performing the electromyography.

What the risks are?

• Bruising.
• Infection at the electrode sites.
• You typically experience a brief and mild shock, which may be a bit unpleasant.
• Bleeding.

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