Electromyography (EMG) is a diagnostic test used to gain information about the functioning of peripheral nerves in the arms and the legs. This test takes from 15 minutes to one hour, depending on how many areas are being tested. An EMG can reveal if a nerve is pinched and provides information on the severity and location of the pinched nerve. Using very tiny needles, an EMG tracks the electrical impulses coming from the brain and/or spinal cord to the affected area.
An instrument records the electrical activity in your muscle. The size, duration and frequency of these signals helps determine if there is damage to the muscle or to the nerves leading up to the muscle.
Your physician may recommend an EMG if you are experiencing weakness or numbness. EMG helps evaluate and diagnose muscle and nerve disorders such as peripheral neuropathy, a pinched nerve/nerve root compression, muscular dystrophy and other muscle disorders (myopathies) and ALS. Often, the results of the EMG are correlated with the results of a nerve conduction study.
Usually the nerve conduction study is done prior to the EMG. Electrodes are placed on your skin over a nerve that your physician wants to study. A small electrical impulse is passed through one electrode and an instrument measures the resulting electrical activity. In some nerve disorders, the speed of the signal is dramatically slowed. This test may be used to diagnose peripheral nerve disorders, such as carpal tunnel syndrome.
“To be part of the development of a world-class neurosurgical program in the state of Maine is to fulfill a personal vision which is shared by all the neurosurgeons of this practice.”
Lee L. Thibodeau, MD, Neurosurgeon