An Introduction to Electrodiagnosis

Electrodiagnosis is a discipline of modern science that uses electric-powered tech for studying human neurophysiology by making use of the science of electrophysiology. 

What is Electrodiagnostic Medicine?

The American Board of Electrodiagnostic Medicine states that electrodiagnostic medicine is a sub-specialty in the field of medicine that uses a neurophysiologic approach to detect or diagnose and then treat patients with neuropsychiatric, neuromuscular and muscular disorders. 

Neurophysiology of Electrodiagnosis:

Every physician should be familiar with the usual neurophysiologic activity of a human nervous system. 

“Nerve impulses, also known as electrical signals, are formed in the brain. They descend through the spinal cord and the peripheral nervous system,” explains Dr. Sean Ataee, MD. “Signals then transfer to a muscle at a neuro-muscular junction (synapse), where acetylcholine is released that causes an electrical activity in the muscle. The electrical signal results in muscle contraction.”

Electrodiagnostic testing is used to estimate the body’s response to that signal which determines if the nerve and muscle are working properly. 

Significance of Electrodiagnostic Testing:

Electrodiagnostic testing assists in obtaining information regarding any type of muscle injury, nerve injury, muscular disease, localization of the injury, as well as its prognosis. It gives functional information about how your nerves or muscles are functioning. If they are functioning appropriately, the nerves send impulses, and the muscles respond to the electrical energy in a certain way. But if there is any malfunctioning, it may be an indication of a neurological or muscular disease.

The main hallmarks of electrodiagnosis are:

1. Neurodiagnostic Study (NDS) or Nerve Conduction Study (NCS)
2. Electromyography (EMG)
3. Evoked potentials (EPs)

1. Role of Nerve Conduction Study (NCS) in Electrodiagnosis:

Nerve conduction (NCS) study calculates the velocity of electrical activity in a person’s senses. The physician stimulates the nerve and measures its electrical potential by fixing specific patches (electrode patches) to the patient’s skin of specific body parts. 

2. Role of Electromyography in Electrodiagnosis:

Electromyography (EMG) permits the doctor to note the electrical activity of the patient’s muscles. The specialist inserts small needles (electrode needles) into the patient’s muscles to measure and note down the muscle function.

Both of these electrodiagnostic tests enable the doctors to find the actual cause of improper function of a nerve or a muscle. 

3. Role of Evoked Potential in Electrodiagnosis:

Evoked Potentials (EPs) are normal physiological responses of the sensory system to various stimuli. Practically, all the sensory modalities cannot be tested. 

These tests are a clinically useful means to do the following:

• Identify the abnormal function of the sensory system when the results of a neurologic test do not show abnormalities.
• Identify unstable disorders when demyelinated diseases are suggested.
• Make a record of the patient’s progress or deterioration with time.

Which Conditions are Diagnosed by Electrodiagnostic Medicine?

Electrodiagnostic testing helps in diagnosing several nerve and muscle diseases which can affect various areas of the body. Carpal tunnel syndrome is a common condition of the wrists which is made worse by repetitive motion. Electrodiagnostic procedures are vital in helping identify injuries of the 7th cranial nerve as well. 

In complex conditions such as Lou Gehrig’s disease (ALS) or multiple sclerosis, electrodiagnosis brings a clearer picture of how the conditions are affecting the body. The same can be said for neuromuscular disorders such as Myasthenia Gravis and muscular dystrophy. Similarly, back pain and neck injuries can be properly diagnosed using electrodiagnostic procedures.

What to Expect During an Electromyography or Nerve Conduction Study Appointment?

Do not apply any body lotions or body creams before your appointment since they can disrupt the examination.

Depending on the type of your examination, a technician will either slide an electrode needle into your muscle or fix the patches on your skin. You may be required to contract or relax your certain muscles where you are experiencing uneasiness or change your postures during the electrodiagnostic examination.

An exam will take 20 minutes to an hour. After your appointment, you will be able to perform daily life activities.

Now the question arises whether the knowledge gathered about electrodiagnosis alters the method of treatment of a patient. In most cases, there is no doubt that testing makes the treatment more effective. By locating the injury and measuring the degree of injury, a physician accurately diagnoses the etiology and puts all his efforts on the actual anatomic problem.