Electromyography and electroneurography

"They are techniques that help in the diagnosis of different diseases, as well as to study their evolution".

DR. MANUEL ALEGRE
DIRECTOR. NEUROPHYSIOLOGY DEPARTMENT

Electromyography and electroneurography are studies aimed at understanding the functioning of the peripheral nervous system (nerve and muscle).

From the nerves, through electroneurography, it is possible to know the speed and amount of conduction. Of the muscle, with electromyography, it is possible to know if both rest and mild or maximum contraction indicate the presence of particular abnormalities.

Electromyography (EMG) is the recording by means of a needle (and very rarely by means of surface electrodes) of the electrical activity of the muscle. The muscle fibers, when contracting, produce discharges that, collected by these electrodes, give normal or indicative patterns of injury at different levels of the neuromuscular system.

These techniques study the peripheral nerves and the muscle and, therefore, are useful for the diagnosis of diseases with loss of strength, weakness or loss of muscle mass, either of a specific area or of upper and lower limbs.

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When are electromyography or electroneurography indicated?

They are very useful techniques for various specialties, especially Neurology, Traumatology, Rehabilitation, Internal Medicine or Endocrinology.

They serve to locate the injured area, specifying if it is a problem of a hand, arm or leg, or if it is something more diffuse and, defining if the injury is a muscle, nerve, trunk or nerve root, or more than one. Locating the injury helps to find the cause.

These are basic techniques in the evolutionary control of diseases already diagnosed that caused the initial damage. This is the case of traumatic injuries that produced important sequels in members.

They will also help to find alterations that will give an idea of how the disease is evolving, indicating affectation, as in diabetes, a disease that requires close control, and that does not give clear alarm signals for the patient until it is too late.

Most frequent indications of this test:

  • Amyotrophic lateral sclerosis.
  • Myasthenia gravis.
  • Myopathies.
  • Diabetic polyneuropathy.
  • Polyneuropathies.
  • Radiculopathies Neuropathies.
  • Carpal tunnel syndrome.

Do you have any of these diseases?

You may need to have an electromyography or electroneurography

How is electromyography or electroneurography performed?

Both electroneurography and electromyography are performed in the Neurophysiology laboratory without prior preparation. The patient does not have to be fasting (in fact it is preferable that he is not).

The duration of the study is approximately half an hour, varying according to the muscles and nerves that need to be explored.

The patient should sit or lie down comfortably, making it easier for the doctor to access the exploration of the corresponding nerves and muscles with the proper posture.

Usually, it is necessary to change as for a normal physical exploration, but it is not always necessary. It requires collaboration from the patient, so nervousness and shyness should be avoided to ask if you do not understand what the doctor is asking you to do.

Although muscles and nerves of the limbs are usually explored, sometimes it is necessary to assess muscles and nerves of the face, neck and trunk.

In electroneurography, electrical stimuli are given that sometimes surprise the patient. The first one is more annoying, but the following ones are better accepted. Some patients may feel uncomfortable.

For electromyography, a puncture with the electrode needle is inevitable. They are very fine needles, but even so, many times it is uncomfortable and sometimes painful. The patient should complain if it is too uncomfortable, but it is not the most common.

  • No special precautions are required for electroneurography.
  • Electromyography is a more aggressive, moderately invasive technique because it involves inserting a needle into several muscles and sometimes moving the electrode.
  • Complications are very rare, but can occur. Both bleeding (which is usually very small, external, but sometimes internal bruising can occur) and local infection are possible if bacteria are dragged from the surface.
  • Therefore, for electromyography it is necessary to take into account the use of certain drugs that can alter blood clotting, such as acetylsalicylic acid or antiaggregants or anticoagulants, since the risk of bleeding when performing the punctures is higher. On occasion, it will cause the doctor to shorten the number of muscles scanned or even decide that it is convenient to suppress the scan.
  • Electroneurography is a slightly uncomfortable technique, since electrical stimuli must be received at such an intensity that they can be felt. However, after the first impression, it is very tolerable and does not usually produce excessive complaints. Stimulation of the facial nerves is more uncomfortable.
  • Also annoying is the stimulus needed for repetitive stimulation, a technique used to diagnose myasthenia gravis and other diseases of the neuromuscular junction.
  • All of these stimuli, although annoying, are not dangerous and do not produce any subsequent damage.

Where do we do it?

IN NAVARRE AND MADRID

The Neurophysiology Service
of the Clínica Universidad de Navarra

The Neurophysiology Service of the Clinic collaborates in the diagnosis and follow-up of patients with diseases affecting the central and peripheral nervous system.

We share research and teaching care objectives with Neurosurgery, Neurology and the Neurosciences Area of the Cima Universidad de Navarra.

The service to the neurological patient benefits from the findings of the research and the new generations of doctors learn to care for their patients with an optimistic sense for the real hope of finding effective cures.

Organized in diagnostic areas

  • Motor Control Area.
  • Electroencephalography Area.
  • Electromyography Area.
  • Sleep Area.
  • Area of Evoked Potentials.
  • Monitoring in the operating room.
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Why at the Clinica?

  • State-of-the-art diagnostic assistance with great work in research and teaching.
  • Specialized nursing team.
  • We work together with the Sleep Unit.

Safer than ever to continue taking care of you

We update safety protocols weekly with the latest scientific evidence and the knowledge of the best international centers with which we collaborate.