Electrodiagnostic studies can be helpful in evaluating weakness, numbness and pain. During an EMG, the physician studies the electrical activity in muscles by inserting a fine needle electrode into selected muscles. Needle insertion may cause mild, temporary discomfort. The needle is not used for injection and no shocks are given. The physician can determine whether the muscle is working normally by viewing the electrical activity displayed on a screen, while listening to audible signals transmitted over a speaker. Disposable, single use needles are discarded after use to prevent the transmission of infectious diseases.
To perform nerve conduction studies, the physician tapes small surface electrodes onto the skin and applies a brief electric stimulus to one portion of the nerve. Nerve stimulation will cause a tingling sensation. The physician can then evaluate the electrical response of the nerve or muscle to which the nerve is attached, and determine if the nerve impulse is conducted normally. Nerve damage and its severity are determined when nerve conduction is either slow or not at all present.
The time required for an EMG/NCS study is approximately one hour. There are no restrictions to activities or meals before or after the test, and there are no permanent after effects.