Electromyography (EMG) is a diagnostic procedure to assess the health of muscles and the nerve cells that control them (motor neurons). Motor neurons transmit electrical signals that cause muscles to contract. An
EMG translates these signals into graphs, sounds or numerical values that a specialist interprets.
An EMG uses tiny devices called electrodes to transmit or detect electrical signals. During a needle EMG, a needle electrode inserted directly into a muscle records the electrical activity in that muscle. A nerve conduction study, another part of an EMG, uses electrodes taped to the skin (surface electrodes) to measure the speed and strength of signals traveling between two or more points.
EMG results can reveal nerve dysfunction, muscle dysfunction or problems with nerve-to-muscle signal transmission.
Your doctor may order an EMG if you have signs or symptoms that may indicate a nerve or muscle disorder. Such symptoms may include: tingling, numbness, muscle weakness, muscle pain or cramping, and certain types of limb pain
EMG results are often necessary to help diagnose or rule out a number of conditions such as: muscle disorders such as muscular dystrophy or polymyositis, diseases affecting the connection between the nerve and the muscle, such as myasthenia gravis, disorders of nerves outside the spinal cord (peripheral nerves), such as carpal tunnel syndrome or peripheral neuropathies, disorders that affect the motor neurons in the brain or spinal cord, such as amyotrophic lateral sclerosis or polio disorders that affect the nerve root, such as a herniated disk in the spine.
What You Can Expect
different sites depending on your symptoms.
Sensations. The electrodes will at times transmit a tiny electrical current that you may feel as a twinge or spasm. The needle electrode may cause discomfort or pain that usually ends shortly after the needle is
removed.If you're concerned about discomfort or pain, you may want to talk to the
neurologist about taking a short break during the exam.
Instructions. During the needle EMG, the neurologist will assess whether there is any spontaneous electrical activity when the muscle is at rest activity that isn't present in healthy muscle tissue — and the degree
of activity when you slightly contract the muscle. He or she will give you instructions on resting and contracting a muscle at appropriate times. Depending on what muscles and nerves the neurologist is
examining, he or she may ask you to change positions during the exam.
After your EMG you may experience some temporary, minor bruising where the needle electrode was inserted into your muscle. This bruising should fade within several days. If it persists, contact your primary care doctor. For many fibromyalgia suffers, don't be surprised if you are left with a bit of anxiety and irritation for the next few days along with dull aches in the areas that were tested. After all, this test is honed for testing nerve impulses which may excite your system longer than the average person. Also, should you feel heightened anxiety or pain, don't be afraid to ask for frequent breaks during the procedure.