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?
American Board of Electrodiagnostic Medicine states that electrodiagnostic medicine is a sub-specialty in the field of medicine that uses 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 (electrical signals) are formed in brain and then descend through spinal cord and the peripheral nervous system. Signals are transferred to a muscle at the synapse (a neuro-muscular junction), 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 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 their is any malfunctioning, it may be an indication of a neurological or muscular disease.
The main hallmarks of electrodiagnosis are:
- Neurodiagnostic Study (NDS) or Nerve Conduction Study (NCS)
- Electromyography (EMG)
- 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 patient’s muscles. The specialist inserts small needles (electrode needles) into 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 disorder when demyelinated diseases are suggested.
- Make record of patient’s progress or deterioration with time.
Which Conditions are Diagnosed by Electrodiagnostic Medicine?
Electrodiagnostic testing helps in diagnosing several nerve and muscle diseases : [7]
- Carpal tunnel syndrome
- Injuries of Facial nerve (7th cranial nerve)
- multiple sclerosis
- Lou Gehrig’s disease(ALS)
- Neck and back injuries
- Neuromuscular disorders like Myasthenia Gravis
- muscular dystrophy
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 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.
Overview :
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.
