Electromyography (EMG) and nerve conduction studies (NCS) for Myositis Diagnosis

This test has two parts.  Nerve conduction studies are used to measure the health of your nerves.  Electric shocks are administered by the nerve conduction technician to skin directly overlying the nerve.  The response is measured by a second set of electrodes applied to the surface of skin.  The strength of these shocks is equivalent to a strong “static-electricity” shock.

During the EMG, the doctor will insert a very thin needle into one muscle at a time.  You will be asked to relax the muscle and then contract the muscle after the needle is inserted.  The needle is connected to a computer that helps the doctor determine whether your muscle is healthy or affected by a disease of the muscle or nerve.  The number of muscles to be tested is highly variable and depends upon your symptoms and what is found during the actual test.

Preparation
Please do not apply lotion to your skin on the day of your appointment as this may interfere with nerve conduction testing.  Also, let your EMG doctor know if you are taking blood thinners prior to the exam.

Risks
The risks of EMG and NCS are minimal.

Results
Your doctors will discuss the results of your EMG and NCS with the physician performing the tests.  These results will be interpreted in the context of the rest of your evaluation.  Usually, your EMG results will be available to you when you meet with your Myositis Center doctor.

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