Neurography / electromyography (EMG) process


Neurography measures the velocities of motor and sensory nerve impulses using specific electrodes to be placed on the skin. At a certain distance from the electrodes with the help of the stimulatory the nerve is stimulated, and the time and distance carried out by the momentum between stimulating and recording electrodes is measured. In addition to neurography the electromyography investigation can be performed as well. Electromyography (EMG) is a diagnostic examination of nerve and muscle health evaluation. During EMG examination, the needle electrode is administered directly into the muscle and it records the electrical activity of the muscle. EMG results can detect nerve and/or muscle malfunctions or problems with synapse (signal transmission place between the nerve and the muscle). EMG converts these signals into graph, sound and numerical values, which are interpreted by a specialist.

Why neurograpy/EMG is needed?
You need to perform neurograhpy and/or EMG, if you have following complaints or symptoms that may indicate a nerve and/or muscle dysfunction:
• tingling;
• numbness;
• muscle weakness;
• muscle pain or cramps;
• certain types of pain in extremities.

The results of neurography/EMG examination are often needed to help diagnose or rule out other diseases, such as:

• muscular disorders – muscular dystrophy, myopathy or myositis;
• diseases caused by disorders of muscle and nerve synapses – myasthenia gravis;
• disorders of the nerves outside the spinal cord (peripheral nerves) – carpal tunnel syndrome or peripheral neuropathy;
• disorders which affect motor neurones in the brain or spinal cord – amyotrophic lateral sclerosis or polio;
• disorders that affect the nerve roots – spinal intervertebral disc protrusion/herniation and spondylosis.

Examination risks
Neurography/EMG examinations is a low risk investigations with rare complications. A little bleeding, infection and nerve damage risks can persist. To minimize the potential risks, disposable needle electrodes are used.

How to prepare for examination?
Usually no special preparation for this examination is required

Prior to examination
Your doctor will explain the nature of the examination and will lead it. You are pleased to ask all questions that may arise. You will be asked to sign a consent form for the examination. Read the form carefully and ask questions if there are any outstanding issues.

Neurologist, prior to the examination needs to know:
• Do you have the pacemaker or other electrical medical device;
• Are you taking blood-thinning medications (anticoagulants);
• Do you have haemophilia or blood clotting disorder that can cause prolonged bleeding;
• Do you have any skin infection, as there is a risk of spreading infection from the skin into the muscle.
• If you are not sure about any other possible risks, associated with your health, please discuss them with your doctor before the examination!

Questions may arise

If you are planning your electromyography (EMG), you can ask the following questions:

Do I need to stop taking the medicine before the examination?
Whether it is necessary to carry out other preparatory activities?

Personal hygiene
Washing prior to procedure is recommended, without use of a skin lotion or cream.

Examination process
Electrodes. Neurologist will deploy electrodes in different places on the skin surface, depending on where you tick symptoms. Neurologist can also insert the needle electrodes in different places in the muscles because of clinical symptoms.
Feelings. Stimulation electrodes will nerve stimulation with electrical current, which is subjectively felt. Administration of the needle electrode can result in some discomfort or pain, which usually ends shortly after the needle is removed. If you are worried about discomfort or pain, you can ask your neurologist for a short break during the examination.
Instructions. During EMG neurologist may ask you to make contraction of the muscle investigated, to evaluate the electrical activity of the muscle.
Examinations. Examinations can range from 30 to 60 minutes.

Online resources
The above text is the reference to other websites (ALS Association, the American Academy of Neurology – Public Education, Muscular Dystrophy Association, the Myasthenia Gravis Foundation of America, National Institute of Neurological Disorders and Stroke, National Institutes of Health (NIH), National Library of Medicine), which contains information on EMG and neurography examinations and related health conditions. We hope that this information will be useful for you. However, we do not control or endorse the information that is provided in these websites.
ALS Association American Academy of Neurology – Public Education
Muscular Dystrophy Association
Myasthenia Gravis Foundation of America
National Institute of Neurological Disorders and Stroke
National Institutes of Health (NIH)
National Library of Medicine

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