EMG (ELECTROMYOGRAPHY)

What is EMG ?

EMG is the abbreviation for electromyography and is an examination procedure, which depands on the examination of electrical potentials of nerves and muscles. It is also called Electroneuromyography ( ENMG ) but the usage of EMG term is more common.The EMG examination consists of nerve conduction studies and examination of muscles with needles. Nerve conduction study is performed by stimulation of the nerves with low-voltage electricity. In the needle EMG  examination, the muscles are evaluated by sticking a needle into the muscle. In other words, this examination is performed by stimulation of the nerves with electrical stimulus and examination of muscles with a needle. The examinations such as repetitive nerve stimulation and single fiber EMG ( SFEMG ) are in fact different examinations but they are also classified under the heading of EMG.

For which diseases is EMG demanded ?

EMG is performed for cases like anterior horn cells ( motor neuron diseases ), roots of nerves    (lumbar and cervical herniated disc) plexus of nerves (obstetric or traumatic ), nerves ( facial paralysis, nerve compressions and traumas, carpal tunnel syndrome, polyneuropathy ), nerve-muscle junction (myasthenia gravis ) or diseases of muscle fibers (myopathy ). It alone has a diagnostic value for some of these diseases and guides for the diagnosis of some of them as an auxillary method for other examinations. EMG is helpful for the diagnosis of peripheral nerve and muscle diseases but has no diagnostic value for diseases of the brain.

Is any preparation necessary for the examination ?

There is neither any need for a preparation nor a need  for fasting. The patients can be of all ages. It is useful to bring previous EMG reports and reports of other examinations related to the ilness (muscle enzymes, imaging ). A clean skin prevents some technical problems to arouse. No creams should be rubbed on the skin. According to the part of the body to be examined, comfortable clothes should be weared on. Tight trousers, tight panty-stockings should not be weared on the day of examination. If the patient is taking anticoagulants (like warfarin, heparin ), has a bleeding deficiency or infectious diseases ( like hepatitis, AIDS ), the doctor should be informed. The doctor should also be informed, if the patient has a cardiac pacemaker, because the examination can be harmful.

How is it performed ?

 EMG examination is performed by a doctor. The technician helps with the nerve conduction examination but the needle application is performed by the doctor. Generally, nerve conduction study is performed first using electrical stimulus and then the muscles are examined using sterile needles. Though the examination is bothersome and sometimes painful, patients say that it is not unbearable. Few or no patients have discontinued the examination untill now. Because no medicament is injected into the muscles during the procedure, it is not as painful as medicament  injections. The region to be examined is not benumbed, because it is not a  practical method. After needle insertion into muscle , examination is performed when the muscle is at rest and when it contracts . EMG is not a standard examination and the doctor bewares unnecesarry  attempts limiting the examination with the help of his/her knowledge and experience. For some patients, only nerve conduction examination is enough but sometimes one or more muscles must be examined. The duration of the examination changes from patient to patient. It lasts 15 min-1 hour. The compliance of the  patient during the examination will prevent the unnecessary prolongation of the procedure. There is no permanent impact of the procedure on the patient. The EMG result is given as a report 15-30 min after the examination is completed.