Electromyography (erg): what is it?

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  • 1Electromyography
    • 1.1What is the essence of the method
    • 1.2Types of research
    • 1.3Indications
    • 1.4How is the procedure performed
    • 1.5Explanation of results
    • 1.6Contraindications
  • 2What is electromyography and where to do it, the indications for carrying out
    • 2.1What processes are being investigated?
    • 2.2Types of EMG
    • 2.3Preparing for the procedure
    • 2.4Method of conducting
    • 2.5Explanation of EMG
    • 2.6Possible complications
  • 3Electromyography (EMG)
    • 3.1How is EMG conducted?
    • 3.2Explanation of EMG
  • 4How passes and what is needed to prepare for the electromyography procedure


In the diagnosis of various diseases of the musculoskeletal system, along with other methods of research, EMG is widely used - electromyography.

It helps to determine the causes of pain in the back and muscles, impaired motor function, the dynamics of the process of restoring motor activity after surgery or trauma.

Electromyography is a method of diagnosis, consisting in the capture of bioelectric potentials of muscles at rest and with contraction, and also in the study of their activity. For the first time it was applied by the German scientist G.

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Piper in 1907, but widely spread only by the middle of the 20th century.

What is the essence of the method

A study is carried out using a special electromyograph device. It captures electrical impulses from the muscles with the help of contact electrodes. The device displays data on the computer screen, where they are recorded and analyzed.

In every movement of a person a lot of muscles are involved, it is on their correct work that many functions of the body depend. Violation of neuromuscular conduction can cause convulsions, numbness, weakness, or pain.

After electromyographic examination it is possible to determine not only the cause of these problems. This method helps to identify the nature of the disorder, the localization and extent of the process, the stage and severity of the lesion of the neuromuscular system.

EMG is performed in order to make an accurate diagnosis, correctly prescribe the treatment and monitor its effectiveness.

Types of research

Modern electromyography is a complex procedure, which has several varieties. Depending on the method and purpose of the study, there are three types of EMG.

  1. Superficial, or global electromyography is the most painless way to examine muscle activity. It consists in the imposition of flat metal electrodes on the skin and allows to obtain the most general picture of the state of the neuromuscular system. In addition, the picture can be distorted by the presence of a fat layer under the skin, involuntary movements of the patient, the correctness of the application of electrodes relative to the muscle. Despite the fact that this type of research is not very informative, it is most often used for children and seriously ill patients.
  2. Needle electromyography is a local study in which electrodes are inserted into the muscle in the form of thin needles. This method is more accurate, but it has its own indications and contraindications. Due to the fact that it causes a slight pain when the needle is inserted, it is often used for adults. Therefore, in which way to examine the patient, the doctor decides, depending on his general condition, diagnosis and concomitant diseases.
  3. Stimulation electromyography helps to determine the degree of damage to nerves and muscles, for example, in paresis or paralysis. It is carried out by analyzing the response of the muscles to their electrical stimulation. With its help, you can determine where the impulse from the nerve to the muscle is broken. Since this study involves nerve fibers, this technique is also called electroneuromyography.

The most painless method of research is the application of electrodes to the skin

Depending on which group of muscles is examined, these types are distinguished: EMG of the upper and lower extremities, masticatory or facial muscles. The study helps determine the causes of their weakness or loss of sensitivity, impaired motor activity.

EMG can be performed both on separate muscles and nerves, for example, when examining the sciatic nerve or facial muscles of the face, and all over the arms or legs.

Usually, when diagnosing the lower and upper extremities, it is necessary to analyze the work of the muscles simultaneously from both sides.

Sometimes it becomes necessary to perform an artificial stimulation of muscle activity with an electric pulse


Electromyography is prescribed for any pathology of the musculoskeletal system associated with impaired motor activity, muscle or nerve fiber damage.

It helps to clarify the diagnosis, and during treatment the disease is used to monitor the effectiveness of therapy.

This technique is needed to determine the cause of such states:

  • weakness, fatigue of muscles;
  • Muscle pain, not associated with trauma or fatigue;
  • frequent convulsions;
  • decrease in muscle mass.

Also you can read: aaraparesis of lower extremities in adults

In addition, there are more serious indications for electromyography. It must be performed with suspicion of diseases of the muscles or nervous system.

This method helps to diagnose at an early stage, when there are no visible symptoms.

In addition, it is necessary in the treatment of botulism, poliomyelitis, micro-stroke to determine the degree of lesion of the neuromuscular system and analyze the dynamics of its recovery.

With the help of EMG, you can determine the presence of myasthenia, myopathy, muscle dystonia, polymyositis. Electromyography of hands and feet is performed with various pathologies of the spine: osteochondrosis, trauma, radiculopathy, disc herniation, radicular syndrome.

Electroneuromyography is the main method for diagnosing various neurological diseases associated with peripheral nerve damage.

It helps in time to diagnose compression of nerve roots, amyotrophic or multiple sclerosis, disease Parkinson's disease, tunnel syndrome, trauma to the nerve roots, brain or spinal cord, and various Neuropathy.

This method is unique in that only it is able to detect at an early stage diabetic lesion of the nerves of the lower limbs.

Local electromyography is also necessary in cosmetology. With her help determine the exact place of administration of Botox with rejuvenating procedures.

Frequent use of electromyography in dentistry is due to the fact that in some pathologies of the teeth, the electrical potential of the muscles decreases.

This method allows you to determine the stage of periodontal disease, the presence of a jaw fracture or inflammatory diseases.

It is used for prosthetics, paralysis of the facial nerve, to control bite correction. Such pathologies often affect the functioning of some mimic, as well as masticatory muscles.

It is necessary to pass EMG several times during the treatment of diseases of the musculoskeletal system. This allows you to monitor its effectiveness, fix improvements or the process of restoring muscles after injuries or surgeries.

EMG allows you to choose the optimal time for the beginning of rehabilitation, to choose the most effective exercises.

This research is also used in joint prosthetics to analyze the rate of recovery of motor activity.

Electromyography allows early diagnosis of many diseases of the musculoskeletal system

But not only for the treatment of pathologies EMG is needed. This method is used to analyze the work of muscles in the performance of a particular job or exercise.

With its help, the coordination of movements, the time of development of fatigue, the peculiarities of the functioning of muscles after transplantation are studied.

In this way, scientists were able to create bioelectrical prostheses, controlled by nerve impulses.

How is the procedure performed

In many Western countries, all rehabilitators are trained in the EMG method. In our country, such a survey is carried out by doctors-diagnosticians. And the decoding of the results and the final diagnosis is made by neurologists, orthopedists, surgeons.

For diagnostics, an electromyograph is used, various electrodes that are connected to devices with fine wiring, as well as an oscilloscope or a computer that records the results.

In addition, sometimes the device is connected to an audio amplifier so that the oscillations of the impulses of the muscle can be heard.

Special preparation for EMG is not required. It can be done both in a hospital and in a polyclinic.

But before the study several hours you can not smoke and eat foods that increase the excitability of the nervous system.

It is also recommended for 3-5 days to stop taking certain medications, especially muscle relaxants.

During the procedure, it is necessary to take a comfortable position, so that the muscles to be examined are relaxed

The entire procedure takes 30-60 minutes. The patient should sit in a chair or lie down and take a comfortable position. The main thing is that the muscles that need to be examined are relaxed.

The doctor treats the skin with an antiseptic and applies electrodes. First, the impulse analysis from the muscle in a relaxed state is done. Then the patient slowly strains her.

Sometimes its activity is stimulated artificially.

In most cases, the procedure is painless, but when carrying out needle electromyography the patient may experience unpleasant sensations in the muscles after it ends.

In this case, he is recommended to do warming compresses and take painkillers.

Sometimes a small bruise is observed at the puncture site, which passes on its own for several days.

Explanation of results

This examination shows different results depending on the severity of the course of the disease. The passage of electrical pulses during the procedure is displayed on the computer screen or an oscilloscope. Their record is a little like the results of an electrocardiogram.

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The picture or paper shows the alternation of pulses of different amplitude and frequency in the form of a graph. Decipherment deals with a doctor who appointed the patient for this examination.

In many diseases, for example, myasthenia gravis or Parkinson's disease, characteristic signs are observed, so the diagnosis can be made immediately.

Data displayed on a computer monitor is analyzed by a physician

It happens that the clinical picture obtained during the study may be distorted. The results depend on the patient's age, physical development, fat layer under the skin.

Violation of blood clotting can also distort them. Sometimes the patient improperly complies with the doctor's instructions, not wanting to strain the muscle when needed.

This does not allow us to consider the process in dynamics.

When the muscles are affected, usually the total number of pulses does not differ from the normal picture. Only their amplitude and duration of passage are reduced.

Gradually, the frequency of oscillations in dystonia is dying after the muscle strain.

A myasthenia gravis is characterized by a rapid decay of their amplitude with continuing strain on the muscle.

With neuropathies and other pathologies of the peripheral nervous system, a low activity of impulses is observed. They are uneven in frequency, sometimes single extraordinary pulses are recorded.

This can be observed with diseases of the spinal cord or Parkinson's disease. And with complete damage to the nerves, the electrical activity of the muscles may be completely absent.

In the case of myotonic convulsions, on the contrary, it can last for a long time.


A common contraindication for any type of EMG is the use of potent drugs that affect the nervous system. It is also not recommended to conduct a survey after physiotherapy.

Like most diagnostic measures, EMG is not done at elevated temperature, acute diseases, epilepsy, mental disorders and skin lesions at the site of application of electrodes.

Hypertensive crisis, an attack of angina pectoris, alcohol intoxication or the presence of a pacemaker can also be an obstacle to this method of examination.

There are certain contraindications for conducting such a survey

Needle electromyography, which is associated with the introduction of needles under the skin, has other contraindications. Do not spend it with a tendency to bleeding, some infections transmitted through the blood, as well as children under 8 years and patients with increased pain sensitivity.

Electromyography is now a very common method for diagnosing various diseases.

It is used by neuropathologists, neurosurgeons, orthopedists, traumatologists, endocrinologists and other doctors.

After all, such a study allows you to analyze the work of the neuromuscular system and determine the causes of pathologies.

A source: http://MoyaSpina.ru/diagnostika/elektromiografiya

What is electromyography and where to do it, the indications for carrying out

The question of the violation of the motor functions of the organism at the present stage is very acute, since it affects besides the physiology the social component of a person's life. Therefore, it is necessary to properly investigate this problem. For this there is a simple, painless and non-traumatic method - electromyography.

Electromyography (EMG) is a method of functional diagnostics of bioelectric potentials that arise in human skeletal muscles when they are contracted. He tracks the process of muscle contraction in general, as a neuromuscular system (NMS).

The structural and functional unit of NMS is the motor unit, which consists of:

  1. Motoneuron- motor cells of the spinal cord.
  2. Peripheral nerve- Connects motoneuron with muscle fiber.
  3. Synapse- the place of contact of the nerve end with the muscle in which the impulse is transferred.
  4. Muscle fiber.

Based on the structure of the neuromuscular system, distinguish the main groups of diseases of the neuromuscular system:

  • Defeat motoneurons (motor neuronal).With this damage, it is necessary to determine the neuronal nature of the lesion and the degree of immobilization of the muscles. The study starts from the most affected muscle, and then the potentials of the same muscle are recorded from the opposite side. Then the electrodes impose the most distant muscular fiber from the opposite side.
  • Neural lesionsare divided into: local - the defeat of one nerve. With these pathologies, the most damaged and symmetrical nerves are examined, the most affected muscle and the most distant from it on the opposite side. Common - the defeat of the functions of several nerves of the lower or upper extremities. With this, one nerve is evaluated on the arm and leg, symmetrical to them. Additionally, the most and least damaged muscles are examined. Generalized - a large number of nerves are involved in the process - polyneuropathy. At the same time, the functionality of all long nerves is recorded. Short assess if necessary.
  • Diseases associated with impaired neuromuscular transmission (synaptic).The main manifestation of them is pathologically fast fatigue. To determine the nature of the disorder of the neuromuscular transmission, stimulating EMG is used, in which a 3-Hz discharge is applied to the nerve.
  • Primary-muscular lesions.The basis of the study is the recording of potentials from the most affected muscles. Also check the function of at least three more: one is the most remote from the lesion on the arm or leg and the two closest on the opposite extremities.

The main objectives of EMG are:

  • Identification of the level of lesion of the neuromuscular system;
  • Determination of the site of injury;
  • Identify the scale of the process (local or common);
  • Determination of the nature of the lesion, its dynamics.

What processes are being investigated?

  1. The muscles are at rest (complete relaxation).The first discharge appears in response to the introduction of the electrode needle - this is a weak muscle contraction. If the biopotential from the muscle is not too pronounced, then it is considered the norm. In the absence of pathology at rest, there should be no discharges from neurons.
  2. The muscle is in a state of weak muscle contraction.The patient slightly strains the muscle and single-cell potentials appear on the electromyogram while maintaining the isoline.
  3. Muscle with maximum reduction.During this reduction, other motor units are involved in the process. This leads to the appearance of many potentials, and they overlap. The contour disappears on the myogram and this phenomenon is called normal interference.

Types of EMG

EMG is carried out with the help of a special apparatus -electromyograph.

To date, it's a computer system that records the potentials coming from the neuromuscular system.

It amplifies them, calculates the amplitude, duration and frequency of oscillations, reduces interference ("noise"), stimulates the muscles.

The electromyograph consists of the device itself and a set of electrodes. Depending on the type of electromyography, different methods are used:

  1. Superficial- non-invasive method that allows you to study many muscles at once, because the electrodes are applied to the surface of the skin. The disadvantage is low sensitivity. It is used for people with increased bleeding or children.
  2. Needle- an invasive method that uses a needle electrode that is injected directly into the muscle. It is more informative, since there is a direct connection between the electromyograph and the muscle fiber.
  3. Stimulating.Use a special stimulating electrode. It causes involuntary contraction of the muscle. This allows you to explore the neural component of the neuromuscular system. Often it is used for diagnosis in neurotrauma. For example, with paralysis: stimulation allows you to know the degree of nerve damage. That is, can a given nerve fiber transmit a pulse at all when the voltage is increased.

There is a subset of stimulatory EMG,which is used in urology, andrology and proctology. This is stimulating sphincterography.

The essence of the method is that the bioelectrical potentials of muscles can be registered from the sphincter of the bladder or the anus, in connection with the synchronism of their contraction.

Stimulatory sphincterographycan be performed with the help of both surface electrodes and needle electrodes, which are attached in the perineal region.

This method, together with cystometry (studies of bladder tone using a manometer), is widely used as an additional method for diagnosing prostate adenoma.

Unlike other stimulants, which work on the principle of continuous supply of current through nerve fibers, EMG does not cause any pain.

Indications for electromyography:

  • Pain or weakness in the muscles.
  • Parkinson's diseaseIs a neurological disease that manifests itself in a characteristic tremor, stiffness of movements, disruption of posture and movements.
  • Convulsions- involuntary contraction of muscle or muscle group, which is accompanied by sharp, prolonged pain.
  • Myasthenia gravis- neuromuscular disease, the main manifestation of which is the pathologically fast fatigue of the muscles.
  • Dystonia- violation of muscle tone.
  • Injuries of peripheral nerves or central nervous system- head or spinal cord
  • Neuropathies- degenerative-dystrophic changes of nerves.
  • Carpal tunnel syndrome(or tunnel syndrome) is a neurological disease characterized by pain and numbness in the hand. It is associated with the compression of the median nerve with the bones and tendons of the hand.
  • Multiple sclerosis- chronic disease of the sheath of nerve fibers of the brain and spinal cord. In this case, multiple scars form on the shells.
  • Botulism- severe toxicological disease of the nervous system, which most often affects the medulla oblongata and spinal cord.
  • Residual phenomena of poliomyelitis.
  • Microinsult.
  • Pain in case of injuries or diseases of the spine (osteochondrosis).
  • In cosmetology(to determine the site for a Botox injection).
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The main contraindications include:

  • Epilepsy or other CNS pathologies;
  • Mental disorders, in which the patient can not behave adequately;
  • Presence of a pacemaker;
  • Acute pathologies of the cardiovascular system - attacks of angina pectoris, hypertensive crisis

Contraindications for carrying out needle electromyography are- infectious diseases that are transmitted through the blood, increased bleeding, low pain threshold.

Preparing for the procedure

Preparation does not require any complex effort. It is enough to observe several details.

The patient mustTo warn about presence at it or him of diseases of system of a blood and the pacemaker.It is necessary to list to the doctor all the medicines that the patient uses. Particular attention should be given to drugs that affect the nervous system and anticoagulants.

Before electromyography, it is necessary to discontinue the use of medicines within 3-4 days, affecting the nervous system, and can change the results of EMG (eg, muscle relaxants or anticholinergics). For 4-5 hours is not recommended to smoke and eat foods that contain caffeine.

Method of conducting

The study can be conductedboth out-patient and in-patient.The patient takes the necessary posture: sitting, half sitting or lying down. Next, the nurse processes the electrodes and the surface of the body, where they will be applied, with an antiseptic solution.

First, the biopotentials of the muscles are examined in a relaxed state, then the patient slowly strains them and at this time fixes new impulses. Then the signal is amplified, processed and transmitted to the writing device.

Explanation of EMG

The electromyogram is a curve recorded on paper with the help of an electromyograph and is similar to a cardiogram. It shows oscillations with different amplitude and frequency.

At the onset of muscle contraction, the amplitude of the oscillations is100-150 μV, with the maximum muscle contraction -1000-3000 μV.

Normally, these parameters can vary under the influence of age and degree of development of muscles.

Changes in the electromyogram for various pathologies:

  1. Primary muscular diseaseare manifested by a decrease in the amplitude of the oscillations with the maximum reduction: in the initial stages up to 500 μV, and in severe cases - up to 150 μV. This can occur with progressive muscular dystrophies, myositis.
  2. With lesions of peripheral nervesthe frequency and amplitude of the oscillations vary: they are equalized, single potentials appear.
  3. With reduced muscle tone on EMGafter an arbitrary contraction of muscles appear low-amplitude, high-frequency, gradually fading vibrations.
  4. With Parkinson's Disease(tremor), characteristic high-amplitude volleys of spindle-shaped oscillations appear.
  5. With diseases of the spinal cordwith muscle weakness and twitching, spontaneous wave-like oscillations, an increase in amplitude are recorded. In a state of rest, spontaneous bioelectrical activity also manifests itself, and with the maximum reduction, a high-amplitude rhythmic potential.
  6. With myasthenia gravis(disorders of neuromuscular transmission) with stimulation electromyography, there is an increasing decrease in the amplitude of the oscillations.

The results of EMG can be affected by:

  • Reception of medicines: muscle relaxants or anticholinergics.
  • Violation in the blood clotting system.
  • Large fat layer at the place of attachment of electrodes.
  • Desire or unwillingness of the patient to strain the muscle.
  • Distance between electrodes.
  • Direction of electrodes relative to muscle fibers.
  • Resistance under the electrodes.
  • Accuracy of installation.
  • The effect of contractions of other muscle groups on the subjects.

Possible complications

The procedure is completely safein all senses.

The only consequence of the procedure may be hematoma (bruise) in the puncture site with a needle. It itself passes for 7 days.

Hematoma occurs when the puncture is carried out in the place of thin, sensitive skin.

The possibility of infection is extremely small, since all research is carried out in compliance with all rules of sterility.


Electromyography is a very common method thathas found wide application in many fields of medicine.Many doctors of different specializations use it in their practice.

EMG helps in diagnosis of neuropathologists, neurosurgeons, endocrinologists, traumatologists and orthopedists, resuscitators, occupational pathologists, proctologists, urologists and andrologists, as well as geneticists. Todayelectromyography is already presented as a separate diagnostic process.

A source: http://SpinaSpina.com/diagnostika/elektromiografiya-chto-eto.html

Electromyography (EMG)

Electromyography is the diagnosis of bioelectric potentials in the muscle when muscle fibers are excited (contracted). For the first time on human electromyography, as early as 1907, the German scientist G. Piper.

At present, the electromyograph is a computer system that records biopotentials, amplifies them, calculates the amplitude, frequency and duration of latency periods, reduces "noise stimulates and analysis.

The potentials are registered by means of dermal or acicular electrodes.

Electrode pins

Needle electromyography

Then the signal is amplified, processed by an electromyograph and transmitted to a visualization device - either on an oscillograph for recording on paper or on a magnetic medium - an electromyogram is recorded. The amplitude of the oscillation of the muscle potential is estimated.

The main types of electromyograms.

The work of the muscles depends on the quality of the muscle fibers themselves and on the full work of the nerves, which conduct a nervous impulse from the spinal cord and brain.

By disturbing the electrical activity of muscles, one can judge the existing disease with the pathology of muscle tissue, determine the cause of weakness (paralysis) of the muscle, its jerking.

The diagnostic method is harmless. There may be a slight soreness in the place where the needle electrode is inserted.

Indications of electromyography:

- complaints of pain and weakness in the muscles, muscle slimming, muscle spasms, muscle twitching and muscle cramps suspicion of the presence of myopathy, myasthenia, myotonia, lateral amyotrophic sclerosis, myoclonus, muscular dystonia, essential tremor, Parkinsonian syndrome, multiple sclerosis, - trauma to peripheral nerves and plexuses, lesion rootlets with degenerative - dystrophic spine pathology, facial nerve neuropathy, polyneuropathy, polymyositis, tunnel syndromes - for assessing the functional state in dynamics and the effectiveness of treatment,

- Local myography is performed to accurately introduce Botox into spastic muscle fibers.

How is EMG conducted?

It is not recommended to conduct a study after taking medications (muscle relaxants, anticholinergics) and physiotherapy procedures, smoking and consuming caffeine (coffee, chocolate, tea, cola). If you have a pacemaker, you are taking anticoagulants, you must tell your doctor about it.

The study is in a relaxed state - lying or sitting. First, remove the potentials at rest, then with a slow muscle strain.

The dermal electrodes record the general indications from the muscle (interference, global EMG), the needle is injected into different parts of the muscle, different muscles (local EMG).

The study uses electrical stimulation of the muscle.

Strap electrodes are paired metal plates up to 1 mm in size, which are superimposed at a distance of 20-25 mm from each other.

For electrostimulation, surface stimulating electrodes are used. Muscle muscles are symmetrical, functionally related to each other, at maximum stress.

Depending on the purpose of the survey, the procedure can last from 15 minutes to an hour.

At rest, with maximum relaxation, biopotentials are not recorded.

Explanation of EMG

At the onset of muscle contraction, oscillations with an amplitude of 100-150 μV appear, with a maximum reduction of 1000-3000 μV (depending on the age of the individual, his physical development).

In primary muscular disease- Myositis, progressive muscular dystrophies, a decrease in the amplitude of the oscillations is recorded.

The decrease in the amplitude correlates according to the severity of the muscle damage - in severe cases up to 20-150 μV at maximum excitation, and with slowly progressing course of the disease and in the initial stages - up to 500mkV.

With a local EMG, a normal total number of action potentials is recorded, but the amplitude and duration are reduced. This is due to a decrease in the number of normal muscle fibers, capable of contraction.

To compensate for the muscle defect in the body, more muscles are activated. This causes an increase in interference and the number of polyphase (multiphase) potentials.

With lesions of peripheral nerve trunks(hereditary, metabolic (including diabetic), toxic (including alcoholic) polyneuropathies) on the global EMG, a decrease in the oscillations, irregular in amplitude and frequency single potentials. The general background of the EMG is characterized by low-amplitude activity. On the local EMG, polyphase action potentials with practically normal characteristics are recorded. When most of the nerve fibers die, the bioelectrical activity of the muscles is gradually inhibited to complete bioelectric silence - there are no potentials.

With spinal amiotrophies- hereditary diseases of spinal cord motoneurons with muscle weakness, muscle twitching local EMG spontaneous activity is recorded in the form of potentials of fibrillation, acute waves, an increase amplitude. Global EMG registers at rest spontaneous bioelectrical activity (fasciculation 100 - 400 microvolts), and at maximum voltage the high amplitude rhythmic potential is the "rhythm of the stockade".

With myotonic syndromes- a group of hereditary diseases with delayed muscle relaxation (dystrophic myotonia, myotonia Thomsen, Becker, Eilenburg ...) muscles are easily excitable and EMG is recorded myotonic aftereffect: low-amplitude, high-frequency electrical activity for a long time after the cessation of arbitrary muscle contraction with a slow gradual fading. On local EMG with myotonia, the increased excitability of muscle fibers is recorded - a series of action potentials of equal amplitude in response to the introduction of a needle electrode.

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With myasthenic syndromes- Violation of the neuromuscular synaptic transmission on the EMG recorded an increasing decrease in the amplitude of the evoked muscular potential with repeated rhythmic stimulation.

With Parkinsonism, an essential tremor- pathology of supra-segmental effects on motoneurons of the anterior horns of the spinal cord, interest of the extrapyramidal system on global EMG recorded rhythmically repeated "volleys" spindle-shaped increase in the amplitude of oscillations and subsequent reduction. The frequency and duration of the "spindles" varies depending on the localization of the pathological process.
For more accurate diagnosis, a joint study is used - electromyography with electroneurography - electroneurography.

A source: http://www.medicalj.ru/diacrisis/instrumental-diagnosis/511-emg

How passes and what is needed to prepare for the electromyography procedure

Electromyography is a unique way to diagnose muscle fibers, which consists in comparing bioelectric potentials, which are transmitted through the neural channels directly to the specified fraction muscle.

All data is read using needle sensors that impart pulses to the electromyograph, and the latter, in turn, displays the image on the oscilloscope.

Comparing the reference picture of the electromyogram with the received, the doctor makes a conclusion about the presence of physiological abnormalities in the work of the muscular system.

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The main information given by electromyography is the amplitude of the oscillations in the potential of muscle fibers. If it is too low, then this is considered the primary sign of the presence of any pathologies in the work of the human neural system.

The whole technology is just tied on the fact that the muscles are brought into action only after the arrival of the electric pulse generated by our body and in particular by the brain.

If at any stage the signal is interrupted, the muscular system simply does not receive information about the required reduction. Accordingly, the motion is not carried out. In medicine, this condition is known as paralysis.

And sometimes it is very difficult to install a nerve, because of which similar violations occur in the work of the musculoskeletal system. It is the electromyography that is designed to eliminate this.

The passage of electromyography is assigned in the following cases:

  • patient complaints of pain in the muscles or joints;
  • probability of myopathy;
  • trauma to the neural system;
  • local paralysis;
  • search for the optimal zone for the introduction of botox (in muscle tissue).

Diagnosis allows you to determine the smallest changes in the power of the transmitted signal, which is important in the treatment of diseases such as epilepsy, Down's syndrome and so on.

It should be noted that most often doctors prescribe the simultaneous passage of electromyography and electroneurography.

The first one allows to determine the activity of muscles during the period of tension and relaxation, and the second one detects the speed of signal transmission from the brain, as well as the permeability of impulses along neural connections.

The study is conducted by a doctor with the help of special equipment. The patient must be completely relaxed at this moment.

In addition, before the procedure it is forbidden to drink coffee, use nicotine, take muscle relaxants of any category, anticoagulants.

It is not recommended to conduct a study for patients who have a synthetic pacemaker or heart valve. The procedure, while absolutely safe, is still connected with the supply of short electrical signals.

If there is any pathology in the work of the neural system, this can provoke a short-term reduction of the heart muscle, which is life-threatening for people with cardiovascular pathologies system.

In the process of electromyography, needle and dermal sensors are connected to the patient. Needles are given impulses, and through the electrodes are read the indices of muscle contraction.

All this is connected to the analyzer, and that, in turn, gives an image to the screen (or graphic polygraph).

The data are then compared with the reference data (measured before electromyography in the patient's calm state in the supine or sitting position).

Is the procedure painful? In most cases, the patient generally does not feel anything. Only in some areas there is a slight tingling sensation, and the skin acquires a reddish tint. All these symptoms completely disappear in 2-3 hours after the study.

To obtain more accurate data, doctors conduct diagnostics by studying paired symmetrical muscles. Thus, the pathology factor in the development of the muscle fibers of the problem zone is excluded.

In the results of research, the most important information is the amplitude at the time of the onset of muscle fiber contraction and at the maximum impulse, that is, when the muscle is strained as far as possible. The difference should be about 3000 μV.

If the indicator is lower, then this is a clear sign of muscle dysfunction. When a problem zone is found, an electroneurography is also conducted there. That is, the nerve fibers are examined for the signal being transmitted.

This method reveals lesions of peripheral neuronal endings, amyotrophy, myotonic syndrome, Parkinsonism, and essential tremor.

By the way, in the detection of suspicions of the above syndromes, electromyography is necessarily reassigned, since it is necessary To exclude the factor of temporal dystrophy of muscles due to the action of any external stimulating factors or pharmacological preparations. For this reason, the patient, who is assigned to the study, is forbidden to eat anything at all until several hours before the procedure, it is recommended to refrain from drinking.

At the end of the procedure, the doctor always gives the patient a schedule of muscle contractions with explanations. By these values ​​you can consult with your doctor and establish the true cause of muscle problems.

Contraindications for electromyography include various somatic diseases, as well as violations in the work of the cardiovascular system.

In some cases, patients with diabetes mellitus are also denied access to the study because of decreased blood clotting.

The same applies to those patients who take medications that reduce this indicator (for example, with blood infection, leukocyte).

It is not recommended to carry out electromyography to pregnant women.

And this is a fairly common problem, since during the period of gestation the child often develops a nerve impairment, accompanied by constant muscle tension and acute pain.

The only way to eliminate this symptom is to solder the nerve roots. However, doctors try to prescribe this procedure only in the most extreme situations, when only thus it is possible to overcome the pain.

As for children, electromyography is not performed for those who did not turn 6 on the day of diagnosis.

Prior to this age, the study is conducted only by decision of the consultation with the consent of the parents. That is, doctors weigh the pros and cons.

the danger of electromyography in this case is a child's panic, because of which it is not possible to conduct a study normally.

Unlike other stimulators, built on the supply of continuous current through the nerve channels, electromyography does not bring any painful sensations at all.

Only occasionally there are miniature bruises, traces of which completely disappear in no more than 10 days.

This occurs only when needle sensors are installed in the area of ​​sensitive skin.

Plus, with the help of electromyography, you can reliably know the nature of the onset of nervous seizures (for example, epileptic ones).

Scientists also found that supplying electricity with a very high frequency of signal fluctuation can provoke a total contraction of muscles.

And thanks to electromyography, it was found that the pathology is related to the fact that the brain, when receiving a signal from the stimulus (in our case current) sends the wrong answer, using several groups muscles. All this combined and is a fit.

Electromyography is conventionally classified into the following types:

  • interference (nonsystematic impulses, with which the joints are examined, since the scan occurs at the moment of flexion / extension of the limbs);
  • local (that is, the contraction of one particular muscle is checked for the given parameters);
  • stimulatory (aimed at the impact of the peripheral nerve).

A certain method is used when searching for a certain group of muscular system dysfunction.

For example, the latter applies only when the patient has a paralyzed part of the body.

Stimulation with electric pulses allows you to find out whether the nerve can transmit a signal at all when the voltage of the transmitted voltage is increased (as measured in millivolts).

A sphincter electromyography is used for a specific type, with the help of which dysfunction of the bladder is detected. It is carried out by both external cutaneous and needle sensors. It is considered one of the most painful among such methods of research of the muscular system.

A source: http://saymigren.net/preparaty/diagnostic/elektromiografiya-chto-eto-takoe.html

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