What does it consist of?
Conventional electromyography is performed by inserting a disposable concentric bipolar needle (steel wire exposed at the tip that functions as an anode, covered by cannula that functions as a cathode) that is inserted into the muscle through the skin and assesses the electrical activity with the muscle at rest, slight contraction and maximum effort. It covers a radius of 1-2.5 mm and allows, as an isolated technique or in combination with neurography, to differentiate neurogenic or myopathic muscle lesions, radiculopathies vs. plexopathies, characterization of polyneuropathies, multineuritis, detection and lesional localization of mononeuropathies, among others.
Isolated fiber electromyography is performed with a sterile needle with a multiple head that covers a radius of less than 300 microns, a complex engineering structure that serves to detect potentials of two muscle fibers belonging to the same motor unit, assessing the “jitter” or differential variation between the activation of one fiber with respect to the other.
CASES IN WHICH IT IS RECOMMENDED
Who is it for?
Your doctor might order an electromyogram if you have signs or symptoms that could indicate a nerve or muscle disorder. These symptoms may include: tingling, numbness, muscle weakness, muscle pain or cramp, or certain types of pain in the extremities
Electromyography results are often needed to help diagnose or rule out certain diseases, such as:
- Muscle disorders, such as muscular dystrophy or polymyositis.
- Diseases that affect the connection between the nerve and muscle, such as myasthenia gravis.
- Disorders of nerves outside the spinal cord (peripheral nerves), such as carpal tunnel syndrome or peripheral neuropathies.
- Disorders that affect motor neurons in the brain or spinal cord, such as amyotrophic lateral sclerosis or polio.
- Disorders that affect the nerve root, such as a herniated disc in the spine.
How should you prepare?
No prior preparation is necessary.