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ElectromyogramEMG is a test that is used to study the operation of the peripheral nervous system and the muscles that innervates. Thanks to it can be diagnosed accurately neuromuscular diseases , congenital or acquired, and it allows you to classify them according to their intensity and origin. The test essentially consists of register using special electrodes the electric currents that form in the nerves and muscles to produce contractions.
The ability that had the muscles to produce electrical currents, thanks to the study of muscles of the fish line was known since the 17TH century. But until 1890 failed to make the first record of muscle electrical activity by the doctor and French photographer E. J. Marey; Since then, the technique was perfected and in the second half of the 20th century were to develop tiny electrodes that could register the electrical activity of cell-to-cell.
With this test you can identify if the neuromuscular disturbances are due to muscle or nerve fibers. So it basically scans:
§ The amplitude of electrical currents.
§ The number of muscle fibers which contract.
§ The time it takes to shrink.
§ While remain collapsed.
Doctor who analyzes such tests is the neurophysiologist or neurologist, and with that initial data can make a pretty close analysis of the origin of the alterations. It is not a very expensive test, but its interpretation can be difficult sometimes, and must always be accompanied by a good full medical study using clinical interview and physical examination. It must be performed by experts, and only when you go to be useful to determine a diagnosis or adjust a treatment. It is usually done on units specific Neuropsychological what's in hospitals and clinics.
Electromyogram is a safe, useful and simple to test, and today is a test routine in many hospitals, even in children.
When an electromyogram is madeElectromyogram is a useful test when the following diseases are suspected:
Neuropathies: non-inflammatory degenerative diseases of the nerve fibers are referred to as neuropathy. They are classified as they affect nerves single, multiple, or so patched all over the body. Its causes are many, may appear in the context of autoimmune diseases, diabetes or alcoholics.
Muscular Dystrophies: there are degenerative muscle diseases appearing since childhood. Muscle fibers do not have sufficient strength and degenerate into fat, this makes skeletal movements and even breathing was difficult. One of the most frequent Dystrophies is Duchenne dystrophy.
Myasthenia gravis: it is an autoimmune disease. In this case there is no involvement or of nerve fibers or muscle fibers, the damage occurs at the junction between ones and others, at the appearance of antibodies directed against the receptors of the electrical signals.
Carpal tunnel syndrome: the nerves that supply the hand allow their movement and their sensitivity. They pass through a fairly narrow tube in the wrist, which sometimes can be too narrow and compress nerves, altering them. The cause is unknown although it has been associated with other diseases.
Lateral sclerosis Amyotrophic: is a congenital disease of the nervous system, of unknown cause and without treatment. Destroyed nerve fibers responsible for movement, from the spinal cord to the muscle.
Guillain-Barré Syndrome: is a disease of the nervous system associated with infections that trigger a reaction of the immune system not well known so far. People who suffer lost nervous performance from the feet upward, sometimes reaching hinder breathing. Resolved over time and often have a good prognosis.
Preparation for an electromyogramIf you are performing an electromyogram these are the issues that you must consider when ready to test:
Duration: electromyogram takes about 20-30 minutes. The only extra time would be the preparation and collection after the test, which in any case would be less than an hour. In winter, if you come from the street, the start of the test usually take a little longer because you have to do it with a proper body temperature.
Income: electromyogram can be performed in a hospital with neurophysiology unit without requiring admission, and then you can go back to your normal life. The only modification required in life habits is not intense physical exercise the five days prior to the test.
Is necessary to be accompanied?: is not necessary to be accompanied.
Drugs: don't need to take any prior medication. Must be communicated to the doctor all the medicines taken regularly, and will decide which suspend or maintain, especially if you take drugs for epilepsy, psychiatric illnesses, antiarrhythmics, relaxing muscular, antiplatelet, anticoagulant and anti-inflammatory.
Food: there is no why stay in fasting prior to testing or after.
Clothes: you can go to the appointment with the same clothes every day, and perhaps ask you to discover the part of the body to study. Avoid creams and products of personal hygiene in that area of the body.
Documents: is essential to present the steering wheel which shows the performance of this test. And you also have to carry the health insurance card and medical history on diseases to study, if you have it, although the doctor will already have it with him. It can give you a document after the test.
Pregnancy and breast-feeding: electromyogram is not contraindicated in pregnancy or lactation, although it is not a test that is performed much in those situations, since some biological constants are altered for itself during these stages.
Contraindications: diseases of the blood coagulation have a relative contraindication, as electrodes are used in the form of thin needles that reach the muscle.
How an electromyogramFirst, the doctor will assess if it can be useful to get an electromyogram. If you see fit, I will quote you one day for the test and you will explain the basic steps you should know. You should avoid exercising the five days before and the day of the test don't get creams and lotions in the area of the body that you go to study.
When you arrive at the hospital and passes to the test room ask you discover the part of your body to study. They apply antiseptic products on the surface of the skin so clean of germs. Then placed sensors in the form of very fine needles that will pass through the skin to the muscle. This can be painful for some people, but it is no different than an intramuscular injection, and not to introduce any medication not rankles both.
The number of electrodes is highly variable, depends on the impairment of neuromuscular study, affected muscle, and the extension of the study. It varies from a single electrode to ten, in the majority of cases. All electrodes have a cable that terminates in an oscilloscope that records all the electrical signals.
Once all the electrodes placed you will be prompted that you make muscle contractions to study or to do certain movements, and the electrodes recorded electrical activity. They can increase discomfort when moving the muscles, but they are only a few seconds. Then will be the test Conversely, electrodes will be shock and will cause muscle contractions.
Once the test completes one electrode will be one. Sometimes it is necessary to press the point of puncture to prevent bleeding. The area will be cleaned again and they will be small dressings at the puncture points. Then you may have to wait for you give you the results, although not come analyzed by the doctor because more time is needed to do this.
Complications of electromyogramElectromyogram is a very little invasive test and does not usually pose any risk for people that is performed. Some complications that have been described in relationship to it is that some of the electrodes can irritate skin in especially sensitive people, something not very common. Bruised and bleeding may appear in people taking medications that alter blood clotting. Infections are extremely unusual, thanks to the use of single-use sterile needles.
Results of an electromyogramDuring the realization of the electromyogram different electrodes pick up electrical signals, which are stored in a memory. At the same time that the test you can see these measurements, but it is virtually impossible to analyze them because it takes time and dedication to study the different parameters.
The neurophysiologist will analyze the number of muscle fibers that is capable of activating a nerve download, with intense contract, there is a long latency from discharge until the contraction, and the duration of each contraction time. If the damage is in the nerve fibers the muscle contraction will not be altered, but the number of muscle fibres activated will be lower, because you will not get the nerve impulse to all. If the damage is in the muscle fibers it will be just the other way around, a correct number of muscle fibers will be activated but its contraction will be altered.
You can go to collect the results of electromyogram medical specialist who sent you the test, and which will normally be a neurologist. On that date it explain the alterations that have been throughout the study. It may necessary to perform more tests requiring more diagnosis, as for example a muscle or nerve biopsy. The treatment options will explain you and will recommend you the most suitable option.