Norm of Electromyography (EMG) and Nerve Conduction Studies (Electromyelogram)
Electromyelogram: no electrical activity at rest. A variety of abnormal electrical patterns produced by diseased muscles at rest and during activity exist and may allow diagnosis of specific myopathy. Nerve conduction studies: normal nerve conduction varies depending on the nerve studied but is in the range 40–70 m/sec.
Usage of Electromyography (EMG) and Nerve Conduction Studies (Electromyelogram)
Nerve conduction studies combined with electromyography can provide useful clues to the existence of neuromuscular disease, primary myopathy, and neuropathic states. Specific disease states that are diagnosed with these techniques include carpal tunnel syndrome, myasthenia gravis, various forms of myositis, Guillain-Barré syndrome, and the myopathies.
Description of Electromyography (EMG) and Nerve Conduction Studies (Electromyelogram)
Electromyogram: One or more needles are inserted into the muscle to be studied. Electrodes are also attached to the skin. Recordings are made at rest after an interval has elapsed subsequent to the needle insertion. Recordings are repeated during a period of voluntary muscle contraction by the client. Nerve conduction study: Electroconductive gel is applied over the nerve to be studied. Electrodes are attached to the nerve to be studied, and an electric current is applied so that velocity measurements can be made. This process can be performed for both motor and sensory nerves.
Professional Considerations of Electromyography (EMG) and Nerve Conduction Studies (Electromyelogram)
Consent form IS required.
Bleeding, interference with pacemaker function, infection at the site of needle insertion.
History of bleeding disorder or chronic anticoagulation therapy, pacemaker.
- Client will bathe or shower the day of the test.
- Avoid skin cosmetic products.
- The physician ordering the tests may ask the client to avoid tobacco and caffeine for several hours before the procedures.
- Fasting before the tests is not necessary.
- Just before beginning the procedure, take a “time out” to verify the correct client, procedure, and site.
- Electromyography: The procedure may be performed with the client either in the sitting or in the supine position. Electrodes are inserted into the muscle of interest and recordings are made at rest and during voluntary contraction of the muscle. The test takes from 30 minutes to an hour to complete.
- Nerve conduction study: A conductive gel is applied to the skin over the nerve of interest, and electrodes are attached at either end of the segment to be studied. An electric current is applied to the nerve segment, and the conduction velocity is measured.
- The conductive gel is cleaned from the skin.
- Hospitalized clients may require transport from the testing location back to their rooms.
- Local application of ice or a cold pack may alleviate postprocedure pain associated with EMG needle placement.
Client and Family Teaching
- The needles used in the EMG procedure are disposable, and the risk of infection is consequently minimal.
- Pain may occur during and after insertion of the EMG needles. This is generally minor, and a local anesthetic is not usually given. Minor discomfort may be associated with the nerve conduction procedure.
Factors That Affect Results
- Cooperation of the client.
- Drugs that affect neuromuscular conduction.
- These techniques may be helpful in the early detection of subclinical diabetic neuropathy.
- Portable equipment is available and can be used in the performance of these procedures.
- This application has primarily been used in the workplace to screen large numbers of workers for carpal tunnel syndrome.