Electrodiagnosis (EDX) is a method of

medical diagnosis Medical diagnosis (abbreviated Dx, Dx, or Ds) is the process of determining which disease or condition explains a person's symptoms and signs. It is most often referred to as diagnosis with the medical context being implicit. The information re ...

that obtains information about

disease A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...

s by passively recording the electrical activity of body parts (that is, their natural

electrophysiology Electrophysiology (from Greek , ''ēlektron'', "amber" etymology of "electron"">Electron#Etymology">etymology of "electron" , ''physis'', "nature, origin"; and , '' -logia'') is the branch of physiology that studies the electrical properties of b ...

) or by measuring their response to external electrical stimuli (

evoked potential An evoked potential or evoked response is an electrical potential in a specific pattern recorded from a specific part of the nervous system, especially the brain, of a human or other animals following presentation of a Stimulus (physiology), stimu ...

s). The most widely used methods of recording spontaneous electrical activity are various forms of electrodiagnostic testing ( electrography) such as

electrocardiography Electrocardiography is the process of producing an electrocardiogram (ECG or EKG), a recording of the heart's electrical activity. It is an electrogram of the heart which is a graph of voltage versus time of the electrical activity of the hear ...

(ECG),

electroencephalography Electroencephalography (EEG) is a method to record an electrogram of the spontaneous electrical activity of the brain. The biosignals detected by EEG have been shown to represent the postsynaptic potentials of pyramidal neurons in the neocortex ...

(EEG), and

electromyography Electromyography (EMG) is a technique for evaluating and recording the electrical activity produced by skeletal muscles. EMG is performed using an instrument called an electromyograph to produce a record called an electromyogram. An electromyog ...

(EMG). Electrodiagnostic medicine (also EDX) is a medical subspecialty of

neurology Neurology (from el, wikt:νεῦρον, νεῦρον (neûron), "string, nerve" and the suffix wikt:-logia, -logia, "study of") is the branch of specialty (medicine), medicine dealing with the diagnosis and treatment of all categories of co ...

, clinical

neurophysiology Neurophysiology is a branch of physiology and neuroscience that studies nervous system function rather than nervous system architecture. This area aids in the diagnosis and monitoring of neurological diseases. Historically, it has been dominated b ...

cardiology Cardiology () is a branch of medicine that deals with disorders of the heart and the cardiovascular system. The field includes medical diagnosis and treatment of congenital heart defects, coronary artery disease, heart failure, valvular heart d ...

, and

physical medicine and rehabilitation Physical medicine and rehabilitation, also known as physiatry, is a branch of medicine that aims to enhance and restore functional ability and quality of life to people with physical impairments or disabilities. This can include conditions su ...

. Electrodiagnostic physicians apply

electrophysiologic Electrophysiology (from Ancient Greek, Greek , ''ēlektron'', "amber" ee the Electron#Etymology, etymology of "electron" , ''physis'', "nature, origin"; and , ''-logy, -logia'') is the branch of physiology that studies the electrical propertie ...

techniques, including needle electromyography and

nerve conduction studies A nerve conduction study (NCS) is a medical diagnostic test commonly used to evaluate the function, especially the ability of electrical conduction, of the motor and sensory nerves of the human body. These tests may be performed by medical spec ...

diagnose Diagnosis is the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different disciplines, with variations in the use of logic, analytics, and experience, to determine " cause and effect". In systems enginee ...

, evaluate, and treat people with impairments of the neurologic,

neuromuscular A neuromuscular junction (or myoneural junction) is a chemical synapse between a motor neuron and a muscle fiber. It allows the motor neuron to transmit a signal to the muscle fiber, causing muscle contraction. Muscles require innervation t ...

, and/or muscular systems. The provision of a quality electrodiagnostic medical evaluation requires extensive scientific knowledge that includes

anatomy Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its ...

and

physiology Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...

of the

peripheral nerves The peripheral nervous system (PNS) is one of two components that make up the nervous system of bilateral animals, with the other part being the central nervous system (CNS). The PNS consists of nerves and ganglia, which lie outside the brain a ...

and

muscles Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscle ...

, the physics and biology of the electrical signals generated by muscle and nerve, the instrumentation used to process these signals, and techniques for clinical evaluation of diseases of the peripheral nerves and sensory pathways.

Training

In the United States, neurologists receive training in performing needle electromyography and nerve conduction studies during a fellowship in clinical neurophysiology or neuromuscular medicine. Physical medicine and rehabilitation physicians receive this training during their residency. and can get further training in a neuromuscular fellowship. The American Board of Electrodiagnostic Medicine certifies US physicians in electrodiagnostic medicine. In Europe, nerve conduction studies and electromyography training may be part of neurology, physical medicine and rehabilitation, or clinical neurophysiology training. In the United States, there is also a certification in neuromuscular medicine. This certification is open only to neurologists and physical medicine and rehabilitation specialists that have completed a fellowship in neuromuscular medicine. The neuromuscular medicine examination includes electrodiagnostic testing as part of the certification examination but also includes broader topics such as genetics, biopsy, and rehabilitation. Technologists sometimes assist in the performance of the NCSs but do not the interpretation. In the United States, the Current Procedural Terminology code of the American Medical Association, states ""Waveforms must be reviewed on site in real time…" In addition, it states that the "Reports must be prepared on site by the examiner, and consists of the work product of the interpretation of numerous test results...along with summarization of clinical and electrodiagnostic data, and physician or other qualified health care professional interpretation. Patients will typically be referred to a specialist in electrodiagnostic medicine if they have numbness, tingling, pain, weakness or spasms. Common muscle and nerve disorders seen by these type of specialists include pinched nerves in the neck or back (

radiculopathy Radiculopathy, also commonly referred to as pinched nerve, refers to a set of conditions in which one or more nerves are affected and do not work properly (a neuropathy). Radiculopathy can result in pain (radicular pain), weakness, altered sensati ...

carpal tunnel syndrome Carpal tunnel syndrome (CTS) is the collection of symptoms and signs associated with median neuropathy at the carpal tunnel. Most CTS is related to idiopathic compression of the median nerve as it travels through the wrist at the carpal tunn ...

, and neuropathies. More uncommon diseases include

ALS Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND) or Lou Gehrig's disease, is a neurodegenerative disease that results in the progressive loss of motor neurons that control voluntary muscles. ALS is the most com ...

myasthenia gravis Myasthenia gravis (MG) is a long-term neuromuscular junction disease that leads to varying degrees of skeletal muscle weakness. The most commonly affected muscles are those of the eyes, face, and swallowing. It can result in double vision, dro ...

, and

chronic inflammatory demyelinating polyneuropathy Chronic inflammatory demyelinating polyneuropathy (CIDP) is an acquired autoimmune disease of the peripheral nervous system characterized by progressive weakness and impaired sensory function in the legs and arms. The disorder is sometimes called c ...

. Using their broader training, physicians in electrodiagnostic medicine, often perform more detailed evaluations which may include laboratory tests, CT or MRI scans, genetic evaluation, biopsy of nerve, skin, or muscle, or perform neuromuscular ultrasound. A more complete listing of disorders and testing can be found under

neuromuscular medicine Neuromuscular medicine is a subspecialty of neurology and physiatry that focuses the diagnosis and management of neuromuscular diseases. The field encompasses issues related to both diagnosis and management of these conditions, including rehabilita ...

Relationship to neurophysiology

Clinical neurophysiology Clinical neurophysiology is a medical specialty that studies the central and peripheral nervous systems through the recording of bioelectrical activity, whether spontaneous or stimulated. It encompasses both research regarding the pathophysiology ...

, is a broader field that includes

EEG Electroencephalography (EEG) is a method to record an electrogram of the spontaneous electrical activity of the brain. The biosignals detected by EEG have been shown to represent the postsynaptic potentials of pyramidal neurons in the neocortex ...

intraoperative monitoring Intraoperative neurophysiological monitoring (IONM) or intraoperative neuromonitoring is the use of electrophysiological methods such as electroencephalography (EEG), electromyography (EMG), and evoked potentials to monitor the functional integ ...

, EMG and

evoked potentials An evoked potential or evoked response is an electrical potential in a specific pattern recorded from a specific part of the nervous system, especially the brain, of a human or other animals following presentation of a stimulus such as a light ...

. The American Board of Psychiatry and Neurology provides certification examination in clinical neurophysiology. The American Board of Electrodiagnostic Medicine provides certification in EDX medicines. The American Board of Clinical Neurophysiology certifies in electroencephalography (EEG), Evoked Potentials (EP), Polysomnography (PSG), Epilepsy Monitoring, and Neurologic Intraoperative Monitoring (NIOM). In the US physicians typically specialize in EEG or EDX medicine but not both.

History

Electrodiagnostic medicine traces its origin back to a 1791 experiment by

Luigi Galvani Luigi Galvani (, also ; ; la, Aloysius Galvanus; 9 September 1737 – 4 December 1798) was an Italian physician, physicist, biologist and philosopher, who studied animal electricity. In 1780, he discovered that the muscles of dead frogs' legs ...

. Galvani depolarized frog leg muscles by using metal rods to make contact with the leg muscles. The development of the

oscilloscope An oscilloscope (informally a scope) is a type of electronic test instrument that graphically displays varying electrical voltages as a two-dimensional plot of one or more signals as a function of time. The main purposes are to display repetiti ...

in 1897 significantly enhanced the ability of scientists to record signals from nerve and muscle. However, it was the needs of those with severe injuries during World War II that created the field of modern electrodiagnostic medicine. In the early 1950s, the first society dedicated to the development of this field, the AAEE, was founded in Chicago by a group of interested specialists in neurology and physical medicine and rehabilitation. James Golseth was instrumental in creating this organization.Archived a
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Over time, newer techniques, such as somatosensory evoked potentials, single fiber electromyography, autonomic testing, and neuromuscular ultrasound have evolved as useful complementary techniques to nerve conduction studies and elecytromyography, which remain the core of electrodiagnostic medicine.

References

External links

American Association of Sensory Electrodiagnostic Medicine

American Association of Neuromuscular & Electrodiagnostic Medicine

Muscle & Nerve
official journal of the AANEM {{Electrodiagnosis Electrophysiology Neurology Rehabilitation medicine

Training

Relationship to neurophysiology

History

References

Further reading

External links