An electromyography (EMG) measures muscle and nerve function. It can help diagnose muscle disorder or nerve dysfunction and might be ordered when a patient experiences persistent numbness, tingling, twitching, paralysis, muscle weakness, or muscle pain.
Typically, a nerve conduction study is performed at the same time as an EMG. During that procedure, small sensors, called electrodes, are placed in the area experiencing symptoms. Your doctor will evaluate how well your nerve cells are communicating with your muscles by sending a mild and brief electrical signal to the nerves. The nerve conduction study can help determine the velocity of nerve response.
An EMG usually follows the nerve conduction study. Small needles will be used to insert microscopic electrodes that act like a microphone into muscles to evaluate electrical activity during rest and contraction. During an EMG, that activity may be recorded, amplified, and displayed on an oscilloscope in the form of waves.
Together, these two tests can help determine whether a patient’s disorder begins in the muscle, nerves, or both. The results can help diagnose several conditions, including muscular dystrophy, inflammation, pinched nerves, a herniated disk, carpal tunnel syndrome, Myasthenia gravis, Lou Gehrig’s disease, Charcot-Marie-Tooth disease, and Guillain-Barre syndrome.
An EMG is extremely safe, though patients may experience some discomfort when the needles are inserted and mild soreness following the procedure.
Tests and Treatments
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