Electromyogram: indications and examination procedure

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Electromyogram: indications and examination procedure

What is an electromyogram?

Mini-lesson of medicine: for a muscle to contract (for example: to walk, to run to dance ...), it must receive an order of the brain, transported in the form of an electrical signal by one - or several - peripheral nerves (at the level of the limbs), having passed through the spinal cord (contained in the spine).

Theelectromyogram is an examination that assesses the functioning of muscles and nerves by measuring the variation of potential that accompanies the contraction: in short, it is to observe the electrical phenomena that occur in one or more muscles.

To know : the electromyogram is a complementary examination, which means that it is performed when the clinical examination is not sufficient to establish the diagnosis.

What are the indications? An electromyogram can be performed when a pathology affecting the peripheral nervous system or a primitive muscular pathology is suspected:

  • Sciatica, cervico-brachial neuralgia,
  • Nerve trauma,
  • Myopathies (Duchenne muscular dystrophy, Becker muscular dystrophy, facio-scapulo-humeral myopathy ...), myasthenia,
  • Carpal tunnel syndrome,
  • polyneuropathies,
  • Amyotrophic Lateral Sclerosis (ALS),
  • Poliomyelitis...

How does an electromyogram take place?

After an explanatory phase and a medical interview, the patient is installed in an extended or semi-recumbent position, depending on the area of ​​the body to be examined. The electromyogram usually takes place in two stages:

  • The examination begins with a electromyogram detection which allows to observe the electrical activity of the muscle concerned by the examination. For this, an electrode is glued to the skin of the patient or directly inserted inside the muscle using a very fine needle. Then, the patient must contract his muscle energetically: the doctor can observe (on a screen) the electrical activity of the muscle at rest and contracted muscle.

To know : sciatica, carpal tunnel syndrome or metabolic disease (diabetes, renal failure ...) can lead to a decrease in the electrical activity of the contraction muscle. On the other hand, electrical activity of the resting muscle may reveal severe muscle damage, such as amyotrophic lateral sclerosis (ALS).

  • Second step: theelectromyogram of stimulo-detection. A nerve is stimulated by short electric pulses at two different points and the electrical potential thus caused is collected by means of an electrode glued to the skin of the patient. The goal: to calculate the speed of nerve, motor or sensitive conduction.

Electromyogram: in practice

  • Without being painful, the electromyogram is not a pleasant examination: if, in certain cases, we can be content with an electrode glued to the skin, certain pathologies require a more precise examination, so a needle electrode inserted into the muscular.
  • The exam lasts between 30 minutes and 45 minutes.
  • It is 100% supported by Social Security.
  • The electromyogram can be prescribed by any doctor suspected of a peripheral or muscular neurological problem: general practitioner, orthopedic surgeon, neurologist, rheumatologist, physical medicine doctor and rehabilitation ...
  • The examination is carried out by a specialist doctor: neurologist, rheumatologist or doctor specialized in physical medicine and rehabilitation.
  • The examination is done at the hospital (public or private) or in a private medical office.
  • The electromyogram with muscle insertion of the electrode is contraindicated in immunocompromised patients (AIDS, immunosuppressive treatment ...) and in patients suffering from coagulation disorders (or under anti-coagulant treatment).
  • There is no minimum age: the electromyogram can also be performed on a newborn, for example after a potentially traumatic birth.

Thanks to Davy Laroche, researcher atInserm and Prof. Jean-Marie Casillas, Professor of Physical Medicine and Rehabilitation University Hospital of Dijon.

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⋙ A solution to preserve the muscles of seniors

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