How neurologist test nerves?

In this brief guide we are going to answer the question ‘’How neurologist test nerves?’’ We will present the main tool to examine the nerves, how it is done, how to prepare and the possible risks.

How neurologist test nerves?

Neurological tests or exams are done to see if the patient’s nervous system is working properly. These tests can be more or less exhaustive depending on what the doctor tries to evaluate, in addition to the age or the state in which the patient is.

The importance of these tests lies in their usefulness in early detection of possible alterations, and thus eliminate or reduce, as far as possible, possible complications that may appear in the long term.

The first tests performed by the clinician are physical tests, in which through the use of hammers, tuning forks, flashlights, etc. the nervous system is tested.

The aspects that are evaluated during this type of neurological examination are:

Mental state (consciousness)

• Reflexes
• Motor skills
• Sensory capabilities
• Balance
• Nerve function
• Coordination

However, in the event that there is suspicion of a possible alteration in any of these aspects, the medical professional has at his disposal a large number of specific and very revealing clinical tests when diagnosing any type of neurological problem.

Now, how neurologist test nerves?

Electrochemical processes take place in our body, which, in other words, means that our body generates electricity or more properly electrical impulses, although, yes, of low intensity. Any muscle or muscle group in the body produces these electrical impulses (let’s clarify that these impulses are actually generated by the nerves that supply the muscles).

As with the electrical activity that occurs in the brain, that of the muscles can also be recorded using a device called an electromyograph, which provides a graphic record called an electromyogram.

This record provides very valuable information based on the electrical activity of the muscles (either by absence, by excess or by defect), based on which numerous conditions of the muscles can be diagnosed, and even determine the exact anatomical location of the problem, and all this with great objectivity and promptness.

What is an electromyogram or electromyography?

It is a neurophysiological diagnostic test whose purpose is to know the functioning of the peripheral nervous system (muscles and nerves and nerves that innervate them), which allows determining if such functioning is adequate or not, that is if the situation is normal or there is some pathological alteration.

It consists of the graphic recording of the electrical activity of the different muscles of the body.

For the electromyographic record, a very fine needle is used, which is inserted into the muscle or area to be explored. Surface electrodes, which are small metal discs, can also be used, although it is much less frequent.

The foundation of the technique is that the muscles, when contracting, emit electrical discharges that are collected by the apparatus known as electromyograph. Depending on how these discharges are, they will indicate that the situation is normal or that there is some injury or pathological alteration.

The usual thing is that an electroneurographic study is carried out simultaneously with the electromyographic examination, which consists of recording the electrical activity of the peripheral nerves that innervate the muscles.

What is electromyography for?

There are really many situations that justify the practice of an electromyogram since this test allows us to determine if there is muscle or neurological damage in the person to whom it is performed.

The main indication of the electromyogram is the study and diagnosis of disorders or diseases whose symptoms are loss of strength or muscle mass, weakness, paresthesia (tingling or numbness), cramps and others.

Similarly, the electromyogram can confirm or rule out the existence of degenerative muscle or neurological diseases, such as dystrophies, sclerosis, and others. It is also used in the diagnosis of diabetic neuropathy, a complication that affects patients with poorly controlled diabetes.

In addition to being used to diagnose a wide variety of neuromuscular disorders or diseases, the electromyogram allows the injured area (a hand, an arm, a leg) to be located with remarkable accuracy, or to determine that it is something more diffuse. And not only this; it also allows identifying the type of structure affected: a nerve, a muscle …

Another of the uses of the electromyogram is the control and monitoring of initially diagnosed neuromuscular diseases or disorders, that is, the study of their evolution and, for example, of the efficacy of the treatment that may have been established.

Finally, it also serves as expert evidence in the judicial field to determine if a person suffers a certain injury. Note that a positive test result shows the existence of injury; On the other hand, a negative result does not rule out the presence of it.

How it is performed?

The electromyogram (and also the electroneurogram that is usually performed simultaneously) is performed in a Neurophysiology office at any time of the day and without the need for the person to undergo any special preparation.

Depending on the area or areas to be explored, the patient must remain seated or lying down on a table, as relaxed as possible and in a cooperative attitude. You will need to bare the area of ​​the body to be studied.

Once in this position, the healthcare professional will place a series of electrodes in the shape of a very fine needle that is inserted into the muscle or muscle group under study. These electrodes are connected to a machine called an oscilloscope.

The electrodes will emit electrical impulses that will cause slight involuntary contractions of the muscles in which they are inserted and, in turn, these contractions will generate electrical activity that will be captured by the electrodes and transmitted to the oscilloscope, where it will be recorded.

This is a type of recording that is performed with the muscle at rest and only subjected to stimulation through the electrodes. At another point in the test, the professional performing the examination will ask the patient to perform certain movements to record the electrical activity of the muscles when they are contracted voluntarily and consciously by the patient.

The duration of the test varies depending on the areas to be explored. The normal thing is that it lasts 20 to 30 minutes.

Preparation for the electromyography

The person who is going to have this test does not need any special preparation. However, there are some considerations to keep in mind, such as the following:

On the day of the test, you should avoid putting creams or lotions on the areas of the body that are going to be explored.

Since a very low body temperature can alter the results of the test, if you arrive very cold you should try to warm up a bit before you have the electromyogram.

Taking certain medications such as antiplatelet drugs and anticoagulants increases the risk of bleeding due to pricks with the small electrode needles. If you are taking any of these medications, tell your testing doctor.

It is possible that you will be advised not to do intense physical activity or exercise in the 4 or 5 days prior to the test.

How does the test feel?

The test does not usually cause great discomfort: for most patients, it is more annoying than painful.

You will be able to feel the prick of the electrodes (sometimes they are very fine needles) and / or the muscle spasms caused by the electrical shocks applied to complete the study. The remarkable technological advancements in the equipment that records the information allow that sometimes the sensors are patches that the electromyographer will place on your skin.

It does not require hospital admission or prior to fasting. Nor is it necessary that you go to the medical center accompanied. They will surely ask you not to do intense physical exercise for a few days before conducting the study. Avoid putting creams or lotions on the area where you will have the electromyogram.

It is normal that you may be a little worried or even suffer certain anxiety before taking this test, especially if you have searched for information or have asked if it hurts on social networks. You should know that every year thousands of patients undergo electromyograms and their experiences are not really what you can read on the Internet.

The perception of discomfort from electromyography is closely related to the pain threshold of each person and the experience and training of the electromyographer: for the vast majority of patients it is more annoying than painful and only in a small number of cases is it a negative experience.

Precautions and risks

The electromyogram recording is a very safe diagnostic procedure in itself, practically free of risks, despite the fact that it is a slightly invasive and aggressive technique (electrode punctures and electric shocks).

It could be the case, very rare, of people who are allergic to the substance of which the electrodes are composed, which could make this test contraindicated in them.

Other risks, very unlikely and that appear exceptionally, are bleeding at the insertion points of the electrodes and infection at these same points. In any case, they would be situations without major clinical significance and easy to solve with the corresponding treatment.

Bruising that may appear in the days after the test is performed at the electrode insertion sites will disappear spontaneously within a few days.

Likewise, the sensitivity or discomfort that may result from the examination will be solved without any complications with the appropriate analgesic medication.

What do the results mean?

If your results are not normal, that can indicate a variety of conditions. Depending on the muscles or nerves affected, it may be:

• Muscle disorders, eg. ex. muscular dystrophy, polymyositis
• Disorders that affect the connection between the motor neuron and the muscle, for example, myasthenia gravis
• Peripheral nerve disorders (nerves outside the spinal cord), eg, carpal tunnel syndrome, peripheral neuropathy
• Conditions that damage motor neurons in the spinal cord or brain, such as poliomyelitis or amyotrophic lateral sclerosis (ALS)
• Conditions that damage the nerve root, for example, spinal disc herniation

So, your doctor told you that you should have electromyography? Don’t be afraid, it won’t hurt. Similarly, all the tests you have to take are to determine that you are in good health.

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References

Marino, J. F. (2013). U.S. Patent No. 8,562,539. Washington, DC: U.S. Patent and Trademark Office.

Oh, S. J. (2003). Clinical electromyography: nerve conduction studies. Lippincott Williams & Wilkins.

Electromyography (EMG). (2020). Retrieved October 27, 2020, from https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/electromyography-emg

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