Electromyography: indications and features of the examination

For patients with a presumptive diagnosis of osteochondrosis, the treating neurologist prescribes various instrumental examination methods, on the basis of which a conclusion is made about the degree of pathological changes.

Electromyography is one of the modern diagnostic methods. This examination is carried out in many medical centers and does not take much time, based on the results obtained, the doctor can choose the most effective therapy regimen.

What is electromyography

The electromyography method is based on fixing biopotentials, that is, electrical activity in skeletal muscles that appear when they are forcibly excited, at rest or during movement. The received data is recorded on special media and then decrypted.

Modern electromyographic devices work with high accuracy, the procedure performed on them is painless and harmless to humans. In the research process, two types of electrodes are used, which are fixed in the required place of the body.

The computer program used in electromyography amplifies and records muscle movements and their activity, calculates the duration, the period of excitation, and then gives a certain analysis of the data obtained.

An electromyogram can be recorded both on paper and on electronic media.

The work of human skeletal muscles directly depends both on the state of the muscle fibers themselves and on the work of the nerve endings that provide their innervation.

Registration during electromyography of certain disorders allows you to determine the degree of pathology of muscle tissues, helps to identify the cause of weakness and the disease itself.

This method of examination is often used during the main treatment, it helps to establish whether the prescribed therapy regimen is effective.

Indications for EMG in spine diseases

In some diseases of the spine, the electrical activity of the muscles is disrupted. An electromyogram helps to determine the degree of violations and its cause . Most often, this study complements others and is assigned:

  • With osteochondrosis, accompanied by various neurological disorders.
  • With radiculitis.
  • Injuries to various parts of the spinal cord.
  • If you suspect a neoplasm of the spine.

The EMG method allows you to establish the localization of a hernia of the spine, with radicular syndrome, it determines changes in nerve fibers. The technique is also used to assess the quality of treatment.


Electromyography is a safe procedure, but since various factors can affect the examination results, it is not prescribed for some of the identified contraindications. Their group includes:

  • Epilepsy and various severe mental disorders.
  • Severe angina attacks, the presence of a pacemaker in the patient.
  • High blood pressure (above 180/11 mm Hg).
  • Fainting and other changes in consciousness of the examined patient.
  • Determination of alcohol intoxication in a patient.

The procedure may also be refused if the integrity of the skin in the place of the body where it is necessary to apply the electrodes is violated.

Preparation for the examination

Before electromyography, the patient receives a consultation from a doctor who explains all the nuances of preparing for the examination.

The neurologist should find out whether the examined person is taking anticholinergics , muscle relaxants, anticoagulants. Before the examination, these drugs are abandoned for a while. Also, the procedure is not performed after physiotherapy methods of treatment or if a person has a pacemaker.

The patient is recommended:

  • Do not consume coffee, chocolate, tonic drinks immediately before EMG.
  • Take a shower before the procedure, which is necessary to “degrease” the skin and hence for a better fit of the electrodes.
  • There is no need to apply cosmetics to the body – creams, lotions before the examination.
  • If the patient uses glasses or lenses, then they come to the study with them. This ensures accurate perception of visual images.

How the research is done

The EMG is performed in a relaxed state, with the patient in a prone position. Installation of electrodes in a sitting position is also possible. Cutaneous electrodes are used, that is, electrodes fixed on the body or needle electrodes inserted deep into the skin.

Electromyography is performed in a state of complete rest and with forced muscle contraction, as the doctor instructs the patient.

Paired metal cutaneous electrodes are applied at a certain distance from each other, the data from them is transmitted to the recording device. The use of cutaneous electrodes is completely safe for the patient and the absence of pain sensitivity.

Unlike cutaneous electrodes, needle electrodes are inserted deep into the skin, into the muscles themselves. The needles used have the thinnest diameter and therefore the pain is minimal. Cutaneous and needle electrodes can be used together or separately from each other. EMG is performed on patients of different ages, including children.

In time, the procedure takes from 15 minutes to one hour. An examination is carried out on an outpatient basis, after which you can go home.

Decoding of diagnostic results

Decryption of the received data is carried out by a qualified specialist. During the examination, the activity of the muscles and the potentials emanating from them are recorded on paper or remain in a computer program, in order to find out the degree of violations they must be compared with the norm.

At rest, the muscles of a person do not have electrical activity. After the electrodes are forced on them, electrical activity appears, which is recorded by the device. The degree of this activity increases as the muscle contraction increases. If there is any pathology, then deviations from the norm are determined.

When decoding EMG, a group of violations can be identified:

  • If there is a primary muscle damage, then the amplitude of the oscillations and their duration are reduced.
  • With the defeat of the peripheral nerve trunks, a decrease in oscillations is noted , potentials uneven in fluctuations appear.
  • In severe neuropathy, with the death of most of the nerve fibers, there is a pronounced inhibition of the bioelectric activity of muscle fibers or a complete lack of response from the muscles.

The amplitude of oscillations, that is, oscillations of muscle contraction, is individual and depends on the age of a person, his physical parameters. Normally, it reaches from 1000 to 3000 μV.

Factors influencing the analysis of the procedure

The accuracy of the data obtained with EMG depends not only on the professionalism of the specialist, but also on other factors. The following criteria may affect the procedure:

  • Accuracy of patient compliance with the doctor’s prescriptions, that is, the correct muscle contraction at the right time.
  • A history of other diseases that affect the state of the neuromuscular system.
  • Correct placement of the electrodes, that is, the distance and location relative to the muscle fibers must be correctly selected.
  • Influence of contraction of all muscles from the examined group.

Also, the patient should always warn the doctor about changes in well-being before the procedure, about taking medications.

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